Nonmelanoma Skin Cancer

The Diagnosis: Porokeratosis of Mibelli

There are 5 variants of porokeratosis: disseminated superficial actinic porokeratosis (DSAP), linear porokeratosis, porokeratosis of Mibelli, porokeratosis palmaris et plantaris disseminata, and punctate porokeratosis. The most common type is DSAP,¹ which is characterized by multiple lesions on the body, particularly in sun-exposed areas. The distinguishing feature of porokeratosis is the cornoid lamella, which is made up of parakeratotic cells extending through the stratum corneum. There also is a thin or absent granular layer beneath it (Figure).²

Patients generally present in the third and fourth decades of life.¹ Risk factors for porokeratosis include sun exposure, immunosuppression, and genetics.^2-4 Overexpression of the protein p53 in porokeratosis lesions has been demonstrated in studies investigating the genetics of porokeratosis.^5,6 A study of Chinese families with DSAP identified 3 different loci associated with DSAP: DSAP1, DSAP2, and DSAP3.² The progression to cancer has been noted in all types of porokeratosis lesions. Malignancies include squamous cell carcinoma, Bowen disease, and basal cell carcinoma.^7,8

Many treatments have been tried for DSAP including cryotherapy, topical 5-fluorouracil, photodynamic therapy, and topical imiquimod with varying success.¹ Our patient was treated with 
cryotherapy but had side effects from treatment including cellulitis and local infections with ulceration before finally healing.

Interestingly, our patient had a single lesion with pathology findings most consistent with DSAP at a later age. Although the pathology suggested DSAP, the size and solitary lesion was more consistent with porokeratosis of Mibelli. Porokeratosis of Mibelli can occur concurrently with DSAP,⁹ but we have not seen other lesions in this patient. We have educated our patient to be aware of other lesions that may occur in the future. Due to risk for malignant conversion, it is generally viewed as beneficial to treat patients who present with porokeratosis lesions. Our patient’s lesion ultimately cleared and he has not developed new lesions at 1-year follow-up.

Although DSAP generally presents in the third and fourth decades of life and porokeratosis of Mibelli during childhood, it is important to educate both dermatologists and primary care physicians to be aware of the possibility of both diagnoses in the elderly population.

The Diagnosis: Porokeratosis of Mibelli

There are 5 variants of porokeratosis: disseminated superficial actinic porokeratosis (DSAP), linear porokeratosis, porokeratosis of Mibelli, porokeratosis palmaris et plantaris disseminata, and punctate porokeratosis. The most common type is DSAP,¹ which is characterized by multiple lesions on the body, particularly in sun-exposed areas. The distinguishing feature of porokeratosis is the cornoid lamella, which is made up of parakeratotic cells extending through the stratum corneum. There also is a thin or absent granular layer beneath it (Figure).²

Patients generally present in the third and fourth decades of life.¹ Risk factors for porokeratosis include sun exposure, immunosuppression, and genetics.^2-4 Overexpression of the protein p53 in porokeratosis lesions has been demonstrated in studies investigating the genetics of porokeratosis.^5,6 A study of Chinese families with DSAP identified 3 different loci associated with DSAP: DSAP1, DSAP2, and DSAP3.² The progression to cancer has been noted in all types of porokeratosis lesions. Malignancies include squamous cell carcinoma, Bowen disease, and basal cell carcinoma.^7,8

Many treatments have been tried for DSAP including cryotherapy, topical 5-fluorouracil, photodynamic therapy, and topical imiquimod with varying success.¹ Our patient was treated with 
cryotherapy but had side effects from treatment including cellulitis and local infections with ulceration before finally healing.

Interestingly, our patient had a single lesion with pathology findings most consistent with DSAP at a later age. Although the pathology suggested DSAP, the size and solitary lesion was more consistent with porokeratosis of Mibelli. Porokeratosis of Mibelli can occur concurrently with DSAP,⁹ but we have not seen other lesions in this patient. We have educated our patient to be aware of other lesions that may occur in the future. Due to risk for malignant conversion, it is generally viewed as beneficial to treat patients who present with porokeratosis lesions. Our patient’s lesion ultimately cleared and he has not developed new lesions at 1-year follow-up.

Although DSAP generally presents in the third and fourth decades of life and porokeratosis of Mibelli during childhood, it is important to educate both dermatologists and primary care physicians to be aware of the possibility of both diagnoses in the elderly population.

The Diagnosis: Porokeratosis of Mibelli

There are 5 variants of porokeratosis: disseminated superficial actinic porokeratosis (DSAP), linear porokeratosis, porokeratosis of Mibelli, porokeratosis palmaris et plantaris disseminata, and punctate porokeratosis. The most common type is DSAP,¹ which is characterized by multiple lesions on the body, particularly in sun-exposed areas. The distinguishing feature of porokeratosis is the cornoid lamella, which is made up of parakeratotic cells extending through the stratum corneum. There also is a thin or absent granular layer beneath it (Figure).²

Patients generally present in the third and fourth decades of life.¹ Risk factors for porokeratosis include sun exposure, immunosuppression, and genetics.^2-4 Overexpression of the protein p53 in porokeratosis lesions has been demonstrated in studies investigating the genetics of porokeratosis.^5,6 A study of Chinese families with DSAP identified 3 different loci associated with DSAP: DSAP1, DSAP2, and DSAP3.² The progression to cancer has been noted in all types of porokeratosis lesions. Malignancies include squamous cell carcinoma, Bowen disease, and basal cell carcinoma.^7,8

Many treatments have been tried for DSAP including cryotherapy, topical 5-fluorouracil, photodynamic therapy, and topical imiquimod with varying success.¹ Our patient was treated with 
cryotherapy but had side effects from treatment including cellulitis and local infections with ulceration before finally healing.

Interestingly, our patient had a single lesion with pathology findings most consistent with DSAP at a later age. Although the pathology suggested DSAP, the size and solitary lesion was more consistent with porokeratosis of Mibelli. Porokeratosis of Mibelli can occur concurrently with DSAP,⁹ but we have not seen other lesions in this patient. We have educated our patient to be aware of other lesions that may occur in the future. Due to risk for malignant conversion, it is generally viewed as beneficial to treat patients who present with porokeratosis lesions. Our patient’s lesion ultimately cleared and he has not developed new lesions at 1-year follow-up.

Although DSAP generally presents in the third and fourth decades of life and porokeratosis of Mibelli during childhood, it is important to educate both dermatologists and primary care physicians to be aware of the possibility of both diagnoses in the elderly population.

Patients who have been on steroids, aspirin, or anticoagulants or who are elderly may have a fragile outer skin layer that is similar to parchment paper, which may be challenging for surgeons. In these patients, the epidermal layer is thin and translucent; when a surgeon cuts through this thin layer, the tissue beneath shows minimal dermis and poor-quality fat with weakened tissue support. When undergoing excisional surgery, there is no strong tissue to help the closure sutures remain intact. Surgeons may struggle with skin tears around the sutures and dehiscence on suture removal.

This article describes a novel approach to skin closure in patients with aging or thin skin using a polyethylene film with an acrylate adhesive in the excision area to aid in maintaining skin integrity throughout the healing process following surgery.

Closure Technique

First, the skin area is cleansed with a sterilizing soap preparation. A sterile marking pen then is used to outline the excision area. A 10×12-cm layer of polyethylene film is then attached to the excision site. Excision of the tumor is performed by cutting through the film in the marked area (Figure 1A), and closure is performed by suturing the wound edges through the polyethylene film while the area is still covered with the film (Figure 1B). The sutures can be left in for 2 weeks or longer if necessary. The patient should be instructed not to remove the film or perform any extensive cleansing of the treatment area. Antibiotics should be administered, as the polyethylene film maintains its sterile integrity for 
7 days only. Because sutures are on the surface of the film, they are easily accessed for removal. 
Figure 1C shows the excision site after removal 
of the sutures and polyethylene film on the left 
tibia of a 95-year-old woman. Adhesive butterfly 
closures can be applied to strengthen the excision area after suture removal and prevent dehiscence.

Figure 1. The excision site was marked after polyethylene adhesive film was applied to a squamous cell carcinoma on the left tibia of 95-year-old woman (A). Closure was performed by suturing the wound edges through the polyethylene film (B). The excision site appeared to have no dehiscence or signs of infection after removal of the sutures and polyethylene film (C).

Case Reports

Twelve procedures for skin cancer excision were conducted in 10 patients using polyethylene adhesive film as a surgical aid due to extremely poor quality of the epidermis. The tumors were all squamous cell carcinomas and were located on the arms and legs. Patients were aged 73 to 95 years. Figure 2 demonstrates an example of excision of a squamous cell carcinoma on the left tibia of an 82-year-old man with prior dehiscence and infection after leg 
surgeries. Good results were achieved using the closure technique described here, along with prophylactic antibiotics.

Figure 2. A squamous cell carcinoma excision site on the left tibia of an 82-year-old man that had been covered with polyethylene adhesive film prior to excision (A) and 17 days following removal of the sutures and film (B).

One patient had complications from a Staphylococcus infection because antibiotics were not administered. The patient had prior infections with other surgeries. Antibiotics were given 4 days after surgery. The infection was cleared and the polyethylene film was retained for a total of 12 days.

Sutures were removed after 14 days for excision sites on the arms and 17 days for excision sites on the legs. All excision sites healed without dehiscence with a cosmetically acceptable scar. 
Figure 3A shows a completed excision on the left hand of a 92-year-old man, and Figure 3B is the 
result 5 weeks after excision.

Figure 3. A squamous cell carcinoma excision site on the left thumb of a 92-year-old man that had been covered with polyethylene adhesive film prior to exci- sion (A). No visible scarring or dehiscence was noted 5 weeks after excision, following removal of the sutures and film (B).

None of the patients reported discomfort from the polyethylene film remaining on the skin following surgery, though postoperative care required extra caution when dressing so as not to disturb or compromise the film. Patients were advised about postoperative care and were instructed not to remove the dressing. They were all given antibiotics as a necessary adjunct to maintain a lessened bacteria burden imposed by an impervious layer of acrylate adhesive. Complications resulted from failure to immediately provide antibiotics to 1 patient. The polyethylene film did not hinder healing or postoperative results.

Comment

Various techniques for handling fragile skin during surgery have been described in the literature. Fomon et al¹ discussed aging skin as it relates to plastic surgery. Foster and Chan² described a skin support technique for closing elliptical incisions in patients with fragile skin. Mazzurco and Krach³ discussed the use of a hydrocolloid dressing to aid in the closure of surgical wounds in patients with fragile skin.

The closure method described here was found to be particularly helpful when used as an adjunct to surgery in patients with fragile skin that lacked a suitable dermis. The polyethylene adhesive film helped to hold the sutures more securely. This method is cost-effective and is associated with a high level of patient satisfaction. For the surgeon, this technique may aid in dealing with difficult surgical situations and helps prevent wound complications in elderly patients or those with fragile skin.

Patients who have been on steroids, aspirin, or anticoagulants or who are elderly may have a fragile outer skin layer that is similar to parchment paper, which may be challenging for surgeons. In these patients, the epidermal layer is thin and translucent; when a surgeon cuts through this thin layer, the tissue beneath shows minimal dermis and poor-quality fat with weakened tissue support. When undergoing excisional surgery, there is no strong tissue to help the closure sutures remain intact. Surgeons may struggle with skin tears around the sutures and dehiscence on suture removal.

This article describes a novel approach to skin closure in patients with aging or thin skin using a polyethylene film with an acrylate adhesive in the excision area to aid in maintaining skin integrity throughout the healing process following surgery.

Closure Technique

First, the skin area is cleansed with a sterilizing soap preparation. A sterile marking pen then is used to outline the excision area. A 10×12-cm layer of polyethylene film is then attached to the excision site. Excision of the tumor is performed by cutting through the film in the marked area (Figure 1A), and closure is performed by suturing the wound edges through the polyethylene film while the area is still covered with the film (Figure 1B). The sutures can be left in for 2 weeks or longer if necessary. The patient should be instructed not to remove the film or perform any extensive cleansing of the treatment area. Antibiotics should be administered, as the polyethylene film maintains its sterile integrity for 
7 days only. Because sutures are on the surface of the film, they are easily accessed for removal. 
Figure 1C shows the excision site after removal 
of the sutures and polyethylene film on the left 
tibia of a 95-year-old woman. Adhesive butterfly 
closures can be applied to strengthen the excision area after suture removal and prevent dehiscence.

Figure 1. The excision site was marked after polyethylene adhesive film was applied to a squamous cell carcinoma on the left tibia of 95-year-old woman (A). Closure was performed by suturing the wound edges through the polyethylene film (B). The excision site appeared to have no dehiscence or signs of infection after removal of the sutures and polyethylene film (C).

Case Reports

Twelve procedures for skin cancer excision were conducted in 10 patients using polyethylene adhesive film as a surgical aid due to extremely poor quality of the epidermis. The tumors were all squamous cell carcinomas and were located on the arms and legs. Patients were aged 73 to 95 years. Figure 2 demonstrates an example of excision of a squamous cell carcinoma on the left tibia of an 82-year-old man with prior dehiscence and infection after leg 
surgeries. Good results were achieved using the closure technique described here, along with prophylactic antibiotics.

Figure 2. A squamous cell carcinoma excision site on the left tibia of an 82-year-old man that had been covered with polyethylene adhesive film prior to excision (A) and 17 days following removal of the sutures and film (B).

One patient had complications from a Staphylococcus infection because antibiotics were not administered. The patient had prior infections with other surgeries. Antibiotics were given 4 days after surgery. The infection was cleared and the polyethylene film was retained for a total of 12 days.

Sutures were removed after 14 days for excision sites on the arms and 17 days for excision sites on the legs. All excision sites healed without dehiscence with a cosmetically acceptable scar. 
Figure 3A shows a completed excision on the left hand of a 92-year-old man, and Figure 3B is the 
result 5 weeks after excision.

Figure 3. A squamous cell carcinoma excision site on the left thumb of a 92-year-old man that had been covered with polyethylene adhesive film prior to exci- sion (A). No visible scarring or dehiscence was noted 5 weeks after excision, following removal of the sutures and film (B).

None of the patients reported discomfort from the polyethylene film remaining on the skin following surgery, though postoperative care required extra caution when dressing so as not to disturb or compromise the film. Patients were advised about postoperative care and were instructed not to remove the dressing. They were all given antibiotics as a necessary adjunct to maintain a lessened bacteria burden imposed by an impervious layer of acrylate adhesive. Complications resulted from failure to immediately provide antibiotics to 1 patient. The polyethylene film did not hinder healing or postoperative results.

Comment

Various techniques for handling fragile skin during surgery have been described in the literature. Fomon et al¹ discussed aging skin as it relates to plastic surgery. Foster and Chan² described a skin support technique for closing elliptical incisions in patients with fragile skin. Mazzurco and Krach³ discussed the use of a hydrocolloid dressing to aid in the closure of surgical wounds in patients with fragile skin.

The closure method described here was found to be particularly helpful when used as an adjunct to surgery in patients with fragile skin that lacked a suitable dermis. The polyethylene adhesive film helped to hold the sutures more securely. This method is cost-effective and is associated with a high level of patient satisfaction. For the surgeon, this technique may aid in dealing with difficult surgical situations and helps prevent wound complications in elderly patients or those with fragile skin.

Patients who have been on steroids, aspirin, or anticoagulants or who are elderly may have a fragile outer skin layer that is similar to parchment paper, which may be challenging for surgeons. In these patients, the epidermal layer is thin and translucent; when a surgeon cuts through this thin layer, the tissue beneath shows minimal dermis and poor-quality fat with weakened tissue support. When undergoing excisional surgery, there is no strong tissue to help the closure sutures remain intact. Surgeons may struggle with skin tears around the sutures and dehiscence on suture removal.

This article describes a novel approach to skin closure in patients with aging or thin skin using a polyethylene film with an acrylate adhesive in the excision area to aid in maintaining skin integrity throughout the healing process following surgery.

Closure Technique

First, the skin area is cleansed with a sterilizing soap preparation. A sterile marking pen then is used to outline the excision area. A 10×12-cm layer of polyethylene film is then attached to the excision site. Excision of the tumor is performed by cutting through the film in the marked area (Figure 1A), and closure is performed by suturing the wound edges through the polyethylene film while the area is still covered with the film (Figure 1B). The sutures can be left in for 2 weeks or longer if necessary. The patient should be instructed not to remove the film or perform any extensive cleansing of the treatment area. Antibiotics should be administered, as the polyethylene film maintains its sterile integrity for 
7 days only. Because sutures are on the surface of the film, they are easily accessed for removal. 
Figure 1C shows the excision site after removal 
of the sutures and polyethylene film on the left 
tibia of a 95-year-old woman. Adhesive butterfly 
closures can be applied to strengthen the excision area after suture removal and prevent dehiscence.

Figure 1. The excision site was marked after polyethylene adhesive film was applied to a squamous cell carcinoma on the left tibia of 95-year-old woman (A). Closure was performed by suturing the wound edges through the polyethylene film (B). The excision site appeared to have no dehiscence or signs of infection after removal of the sutures and polyethylene film (C).

Case Reports

Twelve procedures for skin cancer excision were conducted in 10 patients using polyethylene adhesive film as a surgical aid due to extremely poor quality of the epidermis. The tumors were all squamous cell carcinomas and were located on the arms and legs. Patients were aged 73 to 95 years. Figure 2 demonstrates an example of excision of a squamous cell carcinoma on the left tibia of an 82-year-old man with prior dehiscence and infection after leg 
surgeries. Good results were achieved using the closure technique described here, along with prophylactic antibiotics.

Figure 2. A squamous cell carcinoma excision site on the left tibia of an 82-year-old man that had been covered with polyethylene adhesive film prior to excision (A) and 17 days following removal of the sutures and film (B).

One patient had complications from a Staphylococcus infection because antibiotics were not administered. The patient had prior infections with other surgeries. Antibiotics were given 4 days after surgery. The infection was cleared and the polyethylene film was retained for a total of 12 days.

Sutures were removed after 14 days for excision sites on the arms and 17 days for excision sites on the legs. All excision sites healed without dehiscence with a cosmetically acceptable scar. 
Figure 3A shows a completed excision on the left hand of a 92-year-old man, and Figure 3B is the 
result 5 weeks after excision.

Figure 3. A squamous cell carcinoma excision site on the left thumb of a 92-year-old man that had been covered with polyethylene adhesive film prior to exci- sion (A). No visible scarring or dehiscence was noted 5 weeks after excision, following removal of the sutures and film (B).

None of the patients reported discomfort from the polyethylene film remaining on the skin following surgery, though postoperative care required extra caution when dressing so as not to disturb or compromise the film. Patients were advised about postoperative care and were instructed not to remove the dressing. They were all given antibiotics as a necessary adjunct to maintain a lessened bacteria burden imposed by an impervious layer of acrylate adhesive. Complications resulted from failure to immediately provide antibiotics to 1 patient. The polyethylene film did not hinder healing or postoperative results.

Comment

Various techniques for handling fragile skin during surgery have been described in the literature. Fomon et al¹ discussed aging skin as it relates to plastic surgery. Foster and Chan² described a skin support technique for closing elliptical incisions in patients with fragile skin. Mazzurco and Krach³ discussed the use of a hydrocolloid dressing to aid in the closure of surgical wounds in patients with fragile skin.

The closure method described here was found to be particularly helpful when used as an adjunct to surgery in patients with fragile skin that lacked a suitable dermis. The polyethylene adhesive film helped to hold the sutures more securely. This method is cost-effective and is associated with a high level of patient satisfaction. For the surgeon, this technique may aid in dealing with difficult surgical situations and helps prevent wound complications in elderly patients or those with fragile skin.

Syringoid eccrine carcinoma is a rare malignant adnexal tumor with eccrine differentiation that histologically resembles a syringoma.¹ Originally described as eccrine epithelioma by Freeman and Winklemann² in 1969, syringoid eccrine carcinoma has been reported in the literature as eccrine carcinoma, eccrine syringomatous carcinoma, and sclerosing sweat duct carcinoma.³ Clinically, syringoid eccrine carcinoma most 
commonly presents as a tender plaque or nodule on the scalp, and histologic examination generally reveals a dermal-based lesion that rarely shows epidermal connection. It demonstrates 
syringomalike tadpole morphology (epithelial strands 
with lumen formation) composed of basaloid epithelium with uniform hyperchromatic nuclei 
(Figure 1). There usually is an infiltrative growth pattern to the subcutis (Figure 2 [left]) or skeletal muscle as well as remarkable perineural invasion 
(Figure 2 [right]). Mitotic activity is minimal to absent. The tumor cells of syringoid eccrine 
carcinoma typically show positive immuno-staining for high- and low-molecular-weight cytokeratin, while the lumina are highlighted 
by epithelial membrane antigen and carcinoembryonic antigen.⁴ However, immunohistochemistry 
often is not contributory in diagnosing primary eccrine carcinomas.

Figure 1. Dermal infiltrate with tadpole morphology (arrow) characteristic of syringoid eccrine carcinoma (left)(H&E, original magnification ×40). High-power view shows an epithelial infiltrate and tadpole morphology (arrow)(right)(H&E, original magnification ×400).

Figure 2. Syringoid eccrine carcinoma extending to the junction of the reticular dermis and subcutaneous fat (left) (H&E, original magnification ×100). Nerve with adjacent and invasive basaloid nests of syringoid carcinoma (right)(H&E, original magnification ×100). The tumor consists of monomorphic cells with oval hyperchromatic nuclei.

The differential diagnosis of syringoid eccrine carcinoma includes cutaneous adenoid cystic carcinoma, metastatic adenocarcinoma, sclerosing basal cell carcinoma, and syringoma. Cutaneous adenoid cystic carcinoma is a rare, slow-growing, 
flesh-colored tumor that consists of lobules, islands, and cords of basaloid cells with prominent cystic cribriforming (Figure 3). The tumor cells typically are small, cuboidal, and monomorphic. Metastatic adenoid cystic carcinoma, such as from a primary tumor of the salivary glands or breasts, must be excluded before rendering a diagnosis of primary cutaneous disease.

Figure 3. Striking cribriform architecture of cutaneous adenoid cystic carcinoma (H&E, original magnification ×40). The tumor is well circumscribed and consists of multiple cystic spaces lined by flattened to cuboidal basaloid epithelium.

Metastatic adenocarcinoma of the skin usually presents in patients with a clinical history of preexisting disease. The breasts, colon, stomach, and ovaries are common origins of metastases. The histopathologic and immunohistochemical findings depend on the particular site of origin of the metastasis. Compared with primary eccrine carcinomas, metastatic adenocarcinomas of the skin generally are high-grade lesions with prominent atypia, mitosis, and necrosis (Figure 4).

Figure 4. Metastatic adenocarcinoma of the skin with dermal infiltrating glands (H&E, original magnification ×100). The nuclei are highly atypical. The tumor cells are cytokeratin 7 positive, cytokeratin 20 negative, estrogen-receptor positive, and gross cystic disease fluid protein positive, which is consistent with metastasis from a primary carcinoma of the breast (not shown).

Sclerosing basal cell carcinoma shows basaloid tumor cells with deep infiltration. Unlike syringoid eccrine carcinoma, basal cell carcinoma is an epidermal tumor that does not have true lumen formation. Furthermore, other variants of basal cell carcinoma, including nodular, micronodular, or superficial multicentric tumors, often coexist with the sclerosing variant in the same lesion and constitute a useful diagnostic clue (Figure 5). Staining for epithelial membrane antigen may be useful in identifying the absence of lumen formation, and Ber-EP4 highlights the epidermal origin of the lesion.⁵

Figure 5. Deeply invasive tumor with multiple architectures (sclerosing and micronodular) in a case of sclerosing basal cell carcinoma (H&E, original magnification ×40). Basaloid nests without true lumen formation invade subcutaneous adipose tissue.

Syringomas most commonly present as multiple small flesh-colored papules on the eyelids. On histology, syringomas present as small superficial dermal lesions composed of small ducts that may form tadpolelike structures in a fibrotic stroma (Figure 6). The ducts are lined by benign cuboidal cells. In contrast to syringoid eccrine carcinomas, syringomas usually present as multiple lesions that are microscopically superficial without perineural involvement.

Figure 6. Syringoma is composed of dilated ducts in a fibrotic stroma (H&E, original magnification ×40). Careful microscopic examination would reveal no perineural or deep subcutaneous tumor involvement.

Syringoid eccrine carcinoma is a rare malignant adnexal tumor with eccrine differentiation that histologically resembles a syringoma.¹ Originally described as eccrine epithelioma by Freeman and Winklemann² in 1969, syringoid eccrine carcinoma has been reported in the literature as eccrine carcinoma, eccrine syringomatous carcinoma, and sclerosing sweat duct carcinoma.³ Clinically, syringoid eccrine carcinoma most 
commonly presents as a tender plaque or nodule on the scalp, and histologic examination generally reveals a dermal-based lesion that rarely shows epidermal connection. It demonstrates 
syringomalike tadpole morphology (epithelial strands 
with lumen formation) composed of basaloid epithelium with uniform hyperchromatic nuclei 
(Figure 1). There usually is an infiltrative growth pattern to the subcutis (Figure 2 [left]) or skeletal muscle as well as remarkable perineural invasion 
(Figure 2 [right]). Mitotic activity is minimal to absent. The tumor cells of syringoid eccrine 
carcinoma typically show positive immuno-staining for high- and low-molecular-weight cytokeratin, while the lumina are highlighted 
by epithelial membrane antigen and carcinoembryonic antigen.⁴ However, immunohistochemistry 
often is not contributory in diagnosing primary eccrine carcinomas.

Figure 1. Dermal infiltrate with tadpole morphology (arrow) characteristic of syringoid eccrine carcinoma (left)(H&E, original magnification ×40). High-power view shows an epithelial infiltrate and tadpole morphology (arrow)(right)(H&E, original magnification ×400).

Figure 2. Syringoid eccrine carcinoma extending to the junction of the reticular dermis and subcutaneous fat (left) (H&E, original magnification ×100). Nerve with adjacent and invasive basaloid nests of syringoid carcinoma (right)(H&E, original magnification ×100). The tumor consists of monomorphic cells with oval hyperchromatic nuclei.

The differential diagnosis of syringoid eccrine carcinoma includes cutaneous adenoid cystic carcinoma, metastatic adenocarcinoma, sclerosing basal cell carcinoma, and syringoma. Cutaneous adenoid cystic carcinoma is a rare, slow-growing, 
flesh-colored tumor that consists of lobules, islands, and cords of basaloid cells with prominent cystic cribriforming (Figure 3). The tumor cells typically are small, cuboidal, and monomorphic. Metastatic adenoid cystic carcinoma, such as from a primary tumor of the salivary glands or breasts, must be excluded before rendering a diagnosis of primary cutaneous disease.

Figure 3. Striking cribriform architecture of cutaneous adenoid cystic carcinoma (H&E, original magnification ×40). The tumor is well circumscribed and consists of multiple cystic spaces lined by flattened to cuboidal basaloid epithelium.

Metastatic adenocarcinoma of the skin usually presents in patients with a clinical history of preexisting disease. The breasts, colon, stomach, and ovaries are common origins of metastases. The histopathologic and immunohistochemical findings depend on the particular site of origin of the metastasis. Compared with primary eccrine carcinomas, metastatic adenocarcinomas of the skin generally are high-grade lesions with prominent atypia, mitosis, and necrosis (Figure 4).

Figure 4. Metastatic adenocarcinoma of the skin with dermal infiltrating glands (H&E, original magnification ×100). The nuclei are highly atypical. The tumor cells are cytokeratin 7 positive, cytokeratin 20 negative, estrogen-receptor positive, and gross cystic disease fluid protein positive, which is consistent with metastasis from a primary carcinoma of the breast (not shown).

Sclerosing basal cell carcinoma shows basaloid tumor cells with deep infiltration. Unlike syringoid eccrine carcinoma, basal cell carcinoma is an epidermal tumor that does not have true lumen formation. Furthermore, other variants of basal cell carcinoma, including nodular, micronodular, or superficial multicentric tumors, often coexist with the sclerosing variant in the same lesion and constitute a useful diagnostic clue (Figure 5). Staining for epithelial membrane antigen may be useful in identifying the absence of lumen formation, and Ber-EP4 highlights the epidermal origin of the lesion.⁵

Figure 5. Deeply invasive tumor with multiple architectures (sclerosing and micronodular) in a case of sclerosing basal cell carcinoma (H&E, original magnification ×40). Basaloid nests without true lumen formation invade subcutaneous adipose tissue.

Syringomas most commonly present as multiple small flesh-colored papules on the eyelids. On histology, syringomas present as small superficial dermal lesions composed of small ducts that may form tadpolelike structures in a fibrotic stroma (Figure 6). The ducts are lined by benign cuboidal cells. In contrast to syringoid eccrine carcinomas, syringomas usually present as multiple lesions that are microscopically superficial without perineural involvement.

Figure 6. Syringoma is composed of dilated ducts in a fibrotic stroma (H&E, original magnification ×40). Careful microscopic examination would reveal no perineural or deep subcutaneous tumor involvement.

Syringoid eccrine carcinoma is a rare malignant adnexal tumor with eccrine differentiation that histologically resembles a syringoma.¹ Originally described as eccrine epithelioma by Freeman and Winklemann² in 1969, syringoid eccrine carcinoma has been reported in the literature as eccrine carcinoma, eccrine syringomatous carcinoma, and sclerosing sweat duct carcinoma.³ Clinically, syringoid eccrine carcinoma most 
commonly presents as a tender plaque or nodule on the scalp, and histologic examination generally reveals a dermal-based lesion that rarely shows epidermal connection. It demonstrates 
syringomalike tadpole morphology (epithelial strands 
with lumen formation) composed of basaloid epithelium with uniform hyperchromatic nuclei 
(Figure 1). There usually is an infiltrative growth pattern to the subcutis (Figure 2 [left]) or skeletal muscle as well as remarkable perineural invasion 
(Figure 2 [right]). Mitotic activity is minimal to absent. The tumor cells of syringoid eccrine 
carcinoma typically show positive immuno-staining for high- and low-molecular-weight cytokeratin, while the lumina are highlighted 
by epithelial membrane antigen and carcinoembryonic antigen.⁴ However, immunohistochemistry 
often is not contributory in diagnosing primary eccrine carcinomas.

Figure 1. Dermal infiltrate with tadpole morphology (arrow) characteristic of syringoid eccrine carcinoma (left)(H&E, original magnification ×40). High-power view shows an epithelial infiltrate and tadpole morphology (arrow)(right)(H&E, original magnification ×400).

Figure 2. Syringoid eccrine carcinoma extending to the junction of the reticular dermis and subcutaneous fat (left) (H&E, original magnification ×100). Nerve with adjacent and invasive basaloid nests of syringoid carcinoma (right)(H&E, original magnification ×100). The tumor consists of monomorphic cells with oval hyperchromatic nuclei.

The differential diagnosis of syringoid eccrine carcinoma includes cutaneous adenoid cystic carcinoma, metastatic adenocarcinoma, sclerosing basal cell carcinoma, and syringoma. Cutaneous adenoid cystic carcinoma is a rare, slow-growing, 
flesh-colored tumor that consists of lobules, islands, and cords of basaloid cells with prominent cystic cribriforming (Figure 3). The tumor cells typically are small, cuboidal, and monomorphic. Metastatic adenoid cystic carcinoma, such as from a primary tumor of the salivary glands or breasts, must be excluded before rendering a diagnosis of primary cutaneous disease.

Figure 3. Striking cribriform architecture of cutaneous adenoid cystic carcinoma (H&E, original magnification ×40). The tumor is well circumscribed and consists of multiple cystic spaces lined by flattened to cuboidal basaloid epithelium.

Metastatic adenocarcinoma of the skin usually presents in patients with a clinical history of preexisting disease. The breasts, colon, stomach, and ovaries are common origins of metastases. The histopathologic and immunohistochemical findings depend on the particular site of origin of the metastasis. Compared with primary eccrine carcinomas, metastatic adenocarcinomas of the skin generally are high-grade lesions with prominent atypia, mitosis, and necrosis (Figure 4).

Figure 4. Metastatic adenocarcinoma of the skin with dermal infiltrating glands (H&E, original magnification ×100). The nuclei are highly atypical. The tumor cells are cytokeratin 7 positive, cytokeratin 20 negative, estrogen-receptor positive, and gross cystic disease fluid protein positive, which is consistent with metastasis from a primary carcinoma of the breast (not shown).

Sclerosing basal cell carcinoma shows basaloid tumor cells with deep infiltration. Unlike syringoid eccrine carcinoma, basal cell carcinoma is an epidermal tumor that does not have true lumen formation. Furthermore, other variants of basal cell carcinoma, including nodular, micronodular, or superficial multicentric tumors, often coexist with the sclerosing variant in the same lesion and constitute a useful diagnostic clue (Figure 5). Staining for epithelial membrane antigen may be useful in identifying the absence of lumen formation, and Ber-EP4 highlights the epidermal origin of the lesion.⁵

Figure 5. Deeply invasive tumor with multiple architectures (sclerosing and micronodular) in a case of sclerosing basal cell carcinoma (H&E, original magnification ×40). Basaloid nests without true lumen formation invade subcutaneous adipose tissue.

Syringomas most commonly present as multiple small flesh-colored papules on the eyelids. On histology, syringomas present as small superficial dermal lesions composed of small ducts that may form tadpolelike structures in a fibrotic stroma (Figure 6). The ducts are lined by benign cuboidal cells. In contrast to syringoid eccrine carcinomas, syringomas usually present as multiple lesions that are microscopically superficial without perineural involvement.

Figure 6. Syringoma is composed of dilated ducts in a fibrotic stroma (H&E, original magnification ×40). Careful microscopic examination would reveal no perineural or deep subcutaneous tumor involvement.

Actinic keratosis (AK), also referred to as solar keratosis or senile keratosis, is an intraepidermal proliferation of dysplastic keratinocytes that develops in response to chronic exposure to UV radiation. Actinic keratoses are among the most commonly encountered lesions seen by dermatologists, and it has been estimated that 60% of predisposed individuals older than 40 years have at least one AK.^1,2 Prevalence is notably higher in light-skinned individuals and increases with age, presumably from higher cumulative sun exposure and decreased effectiveness of the immune system.^1,3 It remains a point of contention as to whether or not AKs actually represent squamous cell carcinoma (SCC) in situ, but the potential for progression to invasive disease has been well demonstrated, as the majority of SCCs develop from preexisting AKs.^4-6 The risk for progression to invasive disease for an individual AK has been estimated to range from 0.025% to 16% per year, with an average of approximately 8% in immunocompetent patients.⁷

The clinical morphology of AK can vary widely, but the most common presentation is an erythematous scaly macule, papule, or plaque on sun-exposed skin. The skin surrounding AKs typically shows evidence of solar damage with deep wrinkling, mottled pigmentation, scattered telangiectases, purpura, or xerosis (Figure). A variety of clinical variants with unique presentations exist, including atrophic, hypertrophic, acantholytic, lichenoid, bowenoid, and pigmented subtypes. Because more than 80% of AKs occur on highly visible areas such as the head, neck, back of the hands, and forearms, AKs can have an obvious detrimental effect on cosmetic appearance. Studies also have shown a strong association between AKs and decreased overall quality of life (QOL).^3,8,9

Patient with numerous actinic keratoses, scattered plaques suspicious for squamous cell carcinoma, and numerous scars from prior squamous cell carcinoma treatments.

Topical Treatments

5-Fluorouracil

5-Fluorouracil (5-FU) is a US Food and Drug Administration (FDA)–approved, topically applied pyrimidine analogue that inhibits thymidylate synthase. The resulting suppression of DNA and RNA synthesis induces cell death with a preference for mitotically active cells.¹⁰ 5-Fluorouracil has been used for more than 
50 years as a treatment of AK and its efficacy is well established. A systematic review of 5 randomized controlled studies of topical 5-FU reported an average of 49% of 423 patients achieving complete lesion clearance with 5-FU cream 5% applied once or twice daily for up to 7 weeks.¹¹ Some notable drawbacks of 5-FU, however, are application-site erythema, blistering, pruritus, necrosis, erosion, and pain. These effects often lead to premature cessation of therapy, but newer formulations of 5-FU cream 0.5% have shown good efficacy with better tolerability.¹² A randomized, double-blind, multicenter, parallel-group study of 177 patients using 5-FU cream 0.5% once daily for either 1, 2, or 4 weeks demonstrated significant (P<.001) efficacy over vehicle gel in all treatment arms.¹³ The most effective therapy was 
4 weeks of treatment, which achieved a mean 91.7% reduction in lesion count as assessed 1 month after cessation of therapy. The primary adverse effect (AE) reported in this trial was mild to moderate facial irritation, which generally resolved within 
18 to 21 days after treatment cessation.¹³ Overall, 5-FU is a highly effective therapy for treating AKs that also can improve signs of photoaging, but patients should be aware of cosmetically unappealing effects that generally occur throughout therapy and during the immediate posttreatment period.¹⁴

Chemical Peels

Chemical peels traditionally employ acidic compounds to strip away outer layers of skin to variable depths depending on the concentration of the agent being applied. For treatment of AK, trichloroacetic acid (TCA) is a commonly employed cauterant that has shown efficacy comparable to topical 5-FU as well as ablative CO₂ laser resurfacing.¹⁵ Trichloroacetic acid peels also are a convenient therapy, as good results can be achieved after a single treatment session. A split-face study of 15 patients treated with either a single application of 35% TCA and Jessner solution or twice-daily application of 5-FU cream 5% for 3 weeks demonstrated a reduction in 75% of visible AKs in both treatment arms over a 1-year follow-up period.¹⁶ Although 80% of patients self-reported considerable cosmetic improvement with both therapies, patient preference was reported to be in favor of the TCA peel, given its quick results and relatively mild side effects as compared to 5-FU. Treatment with chemical peels will result in temporary erythema and mild desquamation that usually resolves within 2 weeks; however, there are cases in which erythema has been reported to persist for several months.¹⁶ Adverse effects such as permanent scarring or pigmentation changes rarely are seen with TCA concentrations less than 45%.¹⁷ Caution should be used in patients with a history of herpes simplex virus, keloids, postinflammatory hyperpigmentation, radiation exposure, immunosuppression, and those unable or unwilling to use sunscreen and avoid sun exposure in the immediate posttreatment period.

Diclofenac Sodium

Diclofenac sodium (DFS) is an FDA-approved topical, nonsteroidal, 
anti-inflammatory drug whose mechanism of action in the treatment of AK is thought to involve inhibition of the cyclooxygenase 2 enzyme.¹⁸ The resulting reduction of prostaglandins is believed to inhibit tumor angiogenesis, induce apoptosis, and inhibit cell differentiation.^19-22 In a multicenter, double-blind, placebo-controlled study of 195 patients, application of DFS 3% in hyaluronan gel 2.5% twice daily for 60 days showed significant (P<.05) efficacy over placebo in achieving complete resolution of target lesions during a 30-day follow-up period (31% vs 10%). Furthermore, qualitative patient assessment of complete global improvement also was significantly (P<.05) higher in the active treatment group as compared to placebo (31% vs 10%).²³ Additional studies of DFS 3% in hyaluronan gel 2.5% applied twice daily for 90 days have shown even higher rates of success, with complete resolution of target lesions in 40% to 58% of cases.^24,25 This therapy also has been reported to substantially improve QOL following treatment completion.²⁶ The most frequently cited AEs include pruritus, rash, dry skin, erythema, and application-site reactions. Overall, DFS is a 
well-tolerated therapy with efficacy comparable to that of 5-FU but with a lower incidence of AEs 
and higher patient satisfaction as determined in 
2 head-to-head studies.^27,28
ImiquimodImiquimod (IMQ) is an FDA-approved topical agent that functions as an immune response modifier via agonism of toll-like receptor 7.¹⁸ The resulting cytokine production and release enhances the innate and acquired immune responses leading to anticancer activity.²⁹ The efficacy of IMQ for treatment of AK has been demonstrated in numerous well-designed clinical trials. A 
meta-analysis of 5 randomized, double-blind trials including 1293 patients treated with IMQ cream 5% 
2 to 3 times per week for 12 to 16 weeks reported complete clearance of AKs in 50% of patients treated with IMQ as compared to 5% of patients treated with vehicle.³⁰ The most frequently reported AEs with this therapy include erythema, scabbing, flaking, and erosion. These effects generally resolve following cessation of treatment, and therapy is considered to be well tolerated; however, there are case reports of IMQ triggering or exacerbating existing inflammatory conditions.³¹ Imiquimod cream also is approved at 2.5% and 3.75% concentrations, which have demonstrated significant (P<.001) efficacy over placebo and a reduced incidence of AEs; complete clearance rates have been reported as 30.6% and 35.6%, respectively.³² Notably, a study comparing 75 patients randomized to either IMQ cream 5% 
3 times per week for 4 weeks, 1 or 2 courses of cryosurgery, or 5-FU ointment 5% twice daily for 4 weeks reported that IMQ achieved significantly (P<.01) superior sustained clearance rates during a 12-month follow-up period over cryosurgery and 5-FU 
(73% vs 4% vs 33%).³³ Additionally, cosmetic outcomes as determined by both participants and investigators were reported as excellent at 12 months posttreatment in more than 80% of participants treated with IMQ. These excellent, long-lasting cosmetic outcomes also were determined to be significantly (P<.0001) superior to the cosmetic outcomes of 5-FU and cryotherapy, which both reported excellent outcomes in less than 10% of cases.³³
Ingenol MebutateIngenol mebutate (IM) is a macrocyclic diterpene ester derived from the Euphorbia peplus plant that is FDA approved for the treatment of AK.¹ Ingenol mebutate’s mechanism of action is thought to involve induction of cell death via disruption of the plasma membrane and mitochondria in addition to production of an inflammatory response, which produces tumor-specific antibodies and a large influx of neutrophils.^34,35 The overall evidence for the efficacy of IM is strong. A combined analysis of 4 multicenter, randomized, double-blind studies of 1005 participants reported that IM gel 0.015% applied once daily for 3 days to the face or scalp was significantly superior (P<.001) to placebo in achieving complete clearance as assessed 54 days after completion of therapy (42.2% vs 3.7%) and that IM gel 0.05% applied once daily for 2 days to the trunk or extremities also was significantly superior (P<.001) to placebo in achieving complete clearance as determined 55 days after completion of therapy (34.1% vs 4.7%).³⁶ A follow-up report to this study indicated that IM also appears to achieve long-lasting effects with an overall 87% decrease in total AKs at 12 months follow-up in both trial groups.³⁷ Additionally, it has been recently reported that treatment with IM in these trials was associated with significantly higher overall treatment satisfaction (P<.001) and improved QOL (P<.001) as compared to vehicle.³⁸ Cosmetic outcomes of IM therapy have been assessed in a trial analyzing the efficacy of IM gel 0.025% for 3 days or IM gel 0.05% for 2 or 3 days on nonfacial AKs. This study reported significantly (P<.0001) higher patient satisfaction with the cosmetic outcome at 8 weeks after therapy as compared to vehicle.³⁴ Studies performed in mice have demonstrated that IM is able to promote collagen matrix turnover and impose dermal elasticity, which may contribute to these good cosmetic outcomes.³⁹ The most common AEs of IM therapy are erythema, crusting, and flaking; these effects generally occur 3 to 8 days after starting treatment. These effects, however, generally are short lived and resolve within 2 weeks of treatment cessation when IM is applied to the face or scalp or 4 weeks when applied to the trunk or extremities.⁴⁰ Overall, IM is a useful therapeutic option given its relatively short treatment course as compared to other topically applied agents, as well as its lasting efficacy, mild AEs, and good cosmetic outcomes.

Procedural Modalities

Surgical Procedures

Surgical approaches for the treatment of AK include excision, curettage with or without electrodesiccation, and dermabrasion. In the past, these modalities were used with greater frequency, but the advent of effective topical medications with lower risks of AEs has largely reduced their use.⁴¹ Excision may still be indicated in cases where SCC is suspected, and curettage can be used for treatment of thicker hypertrophic AKs.⁴² Although these approaches have not been evaluated in clinical trials, they are generally effective but require the use of local anesthetics and come with substantial risk for infection, permanent scarring, and hypopigmentation. Dermabrasion employs the use of a motorized device equipped with an abrasive material to physically remove superficial layers of the skin. Studies are limited, but this method has been reported as an effective treatment in a retrospective review of 23 participants in which 96% remained free of AKs at 1 year, 83% at 2 years, 64% at 4 years, and 54% at 5 years posttherapy.⁴³ Notably, one split-face study of 40 participants treated with dermabrasion followed by 25% TCA on one side and either Jessner solution and 35% TCA or dermabrasion alone on the other side reported that the combination of dermabrasion with 25% TCA consistently produced excellent cosmetic results with nearly complete eradication of AKs.⁴⁴ In general, however, cosmetic outcomes with dermabrasion are variable, as the technique is highly operator dependent and treatment is associated with notable discomfort as well as risk for scarring and permanent pigmentation alteration.

Cryotherapy

Cryotherapy remains one of the most commonly utilized treatments of AK and involves the delivery of liquid nitrogen via a spray device or a cotton tip applicator to rapidly freeze cells, thus causing cellular destruction via ice crystal formation and protein denaturation.⁴⁵ Efficacy with this technique has been reported to be as high as 98.8% at 12 months follow-up, but more recent studies cite lower rates of success.⁴⁶ A prospective multicenter study of 90 participants with 421 AKs on the face or scalp treated with a single freeze-thaw cycle of liquid nitrogen reported an overall complete response rate of 67.2% at 3 months posttherapy. Additionally, higher complete response rates were associated with longer freeze times, and cosmetic outcomes were reported as good to excellent in 94% of complete response lesions.⁴⁷ Similar results were reported in an open-label, prospective, randomized, controlled clinical trial of 200 participants with 
543 AKs, which compared a single freeze-thaw cycle with liquid nitrogen to a single session of CO₂ laser ablation in the treatment of isolated AKs of the face and scalp.⁴⁸ At 3 months posttherapy, complete clearance was observed in 71.6% of participants treated with cryotherapy and in 65.3% of participants treated with laser ablation (P=.532). At 
12 months posttherapy, participants who originally showed complete response at 3 months were assessed for relapse. Complete clearance was preserved in 72.6% of participants treated with cryotherapy versus 21.9% of participants treated with laser ablation (P<.0001), and cosmetic outcomes were reported by participants as good or excellent at 3 months follow-up in more than 93% of participants for both treatment arms.⁴⁸ Possible AEs of cryotherapy include pain during treatment, blister formation with possible hemorrhage, infection, scarring, and permanent pigmentary changes.^47,48 Notably, the risk for hypopigmentation increases with longer freezing times, thus requiring clinicians to consider the balance between improved efficacy and reduced cosmetic outcomes.⁴⁷

Light-Based Therapies

Laser Therapy

Ablative laser resurfacing with either the CO₂ or erbium-doped:YAG (Er:YAG) laser utilizes light of specific wavelengths to selectively induce thermolysis and destruction of the epidermal layer. Both lasers have been studied as treatments of AK, but there is a lack of large, well-designed studies. In one small study of 14 participants treated with 
1 to 2 passes of the CO₂ laser, complete clearance was reported in all cases without any recurrences during a follow-up period of 6 to 24 months. Additionally, all participants in this study reported satisfaction with the cosmetic outcome.⁴⁹ The CO₂ laser also has demonstrated efficacy comparable to that of the TCA peel and 5-FU therapy in a prospective randomized trial of 34 patients with facial or scalp AKs who received either CO₂ laser with 2 passes, 30% TCA peel, or 5-FU cream 5% twice daily for 
3 weeks.¹⁵ Reduction in mean AK counts at 3 months posttherapy was significantly (P<.03) higher in all treatment arms as compared to the control group (92% for CO₂ laser, 89% for TCA peel, and 83% for 5-FU cream). No significant (P=.31) difference in outcomes was noted among the different treatment arms.¹⁵ Similar results were reported for the Er:YAG laser in a small prospective study of 5 participants treated with 2 to 3 passes with the Er:YAG laser in which reduction in mean AK counts was reported as ranging from 86% to 96% at 3 months posttherapy.⁵⁰ The Er:YAG laser in combination with the CO₂ laser has shown notable long-term efficacy in achieving higher lesion clearance rates and sustained complete clearance rates over treatment with topical 5-FU.⁵¹ In a prospective randomized study of 55 par-ticipants with multiple AKs on the face or scalp, participants were assigned to receive either combination laser ablation with the Er:YAG and CO₂ lasers down to the level of the papillary dermis or 
5-FU cream 5% applied twice daily for 2 to 7 weeks until an appropriate clinical inflammatory response was achieved. At 12 months follow-up, the laser treatment group achieved significantly (P=.048) higher mean lesion clearance rates (91.1%) as compared to the 5-FU arm (76.6%) and significantly (P=.003) higher sustained complete clearance rates (59.3%) as compared to 5-FU (29.2%). The proportion of participants with an improvement in photoaging score at 12 months follow-up approached statistical significance (P=.07), with 74% of the laser-treated group showing improvement as compared to 43% of the 5-FU–treated group. Long-term, cosmetically unappealing side effects such as erythema and hypopigmentation occurred notably more often in the laser-treated group as compared to the 5-FU group.⁵¹ In summary, ablative lasers appear to be a highly effective therapy for AK but at the cost of increased risk for AEs such as permanent pigmentary changes, prolonged erythema lasting up to several months, and scarring.^50,52-55

Fractional photothermolysis is a relatively new advancement in the field of laser therapy that has received FDA approval for the treatment of AK.⁵⁶ This treatment works by creating multiple noncontiguous microscopic columns of thermal injury while sparing adjacent zones of viable tissue.⁵⁷ Although there are limited studies involving the use of such lasers in the treatment of AK, initial findings suggest that 1927-nm thulium lasers may be more effective than 1550-nm erbium lasers in achieving lesion clearance. A trial of 14 participants who received 5 laser treatments with a 1550-nm fractionated erbium-doped fiber laser reported an average reduction in AK counts of 66.2% at 3 months follow-up and a 55.6% reduction at 6 months follow-up. A participant-determined marked or very significant improvement of lesions was reported in 83% of participants at 1 month posttreatment but only in 44% of participants at 6 months posttreatment.⁵⁸ A similar trial of 24 participants treated with up to 4 treatment sessions of the fractionated 1927-nm thulium laser reported an 87.3% reduction in number of AKs at 3 months follow-up and an 86.6% reduction at 
6 months follow-up.⁵⁶ The primary advantage of fractional laser therapy is a faster recovery period generally lasting only 2 or 3 days as compared to 
2 weeks or more with traditional ablative lasers, thus limiting the amount of time a patient must tolerate cosmetically unappealing erythema.^59,60 The quick recovery time has been attributed to the fractional laser’s ability to preserve the stratum corneum and skin barrier, which also helps reduce the risk for other AEs such as scarring and infection.^56,59-61 Additional studies are needed to better assess the true efficacy of fractional laser therapy, but treatment with the fractional 1927-nm thulium laser appears to be a promising and well-tolerated therapeutic option for treatment of AK with similar efficacy to traditional ablative lasers but with a lower risk of AEs.

Photodynamic TherapyPhotodynamic therapy (PDT) is an FDA-approved treatment that involves the use of a topical photosensitizing agent such as 5-aminolevulinic acid (ALA) or methyl aminovulinate (MAL) before exposure to an activating light source to generate reactive oxygen species that lead to cell death.^62-65 Multiple PDT regimens with varying combinations of photosensitizers, incubation time, and light sources have been studied, but a 
2012 Cochrane review determined that treatment with conventional formulations of MAL and ALA with either blue- or red-light PDT were similarly efficacious for treatment of individual AKs as compared to vehicle with blue- or red-light PDT. One exception was that longer incubation time (ie, 4 hours) with ALA resulted in better results than shorter incubation times (ie, 0.5, 1, 2 hours) with ALA.⁶⁶

Standard PDT treatment with MAL also has consistently demonstrated superior efficacy in achieving complete clearance rates in addition to superior cosmetic outcomes over treatment with either cryotherapy, DFS, or 5-FU.^67-73 Three studies in particular noted an excellent or good investigator-determined cosmetic outcome in 96% to 98% of participants treated with MAL-PDT.^69,71,74 Photodynamic therapy with ALA also has been reported as superior over CO2 laser ablation for AK reduction as well as both patient and investigator overall satisfaction.⁷⁵

More recently, several methods of improving photosensitizer delivery have been studied, which have demonstrated remarkable efficacy at achieving lesion clearance over standard cream formulations or application routines. One such method involves the use of gentle heating to increase photosensitizer uptake. In a split-extremity study of 20 participants who were treated with 20% ALA under occlusion for 1 hour with one side heated to 38.8°C, the heated side demonstrated significant (P<.0001) efficacy at achieving higher median clearance rates over control when evaluated at 2 and 6 months posttherapy.⁷⁶ Notably, occlusion of ALA in itself during the incubation period also has been demonstrated to significantly (P<.0001) improve clearance rates.⁷⁷ Another method involves the use of a new nanoemulsion-based formulation of 
ALA gel, known as BF-200 ALA, which has demonstrated remarkable efficacy over standard 
MAL cream and placebo in a long-term follow-up 
analysis of 2 prospective, randomized, controlled trials.⁷⁸ In a similar vein, 3 prospective randomized trials with a minimum follow-up time of 3 months demonstrated that MAL-PDT in combination with fractional ablative laser pretreatment has significant (P<.02 in all trials) efficacy over MAL-PDT without pretreatment in achieving complete AK clearance. Although the cosmetic outcomes were good or excellent in 87% to 100% of patients, they were not significantly different from stand-alone 
MAL-PDT treatment in any of the trials.^79-81 However, pretreatment with microneedling in MAL-PDT has been shown to achieve superior cosmetic outcomes over 
MAL-PDT without microneedling, according to one small split-face study of 10 participants.⁸²

Overall, PDT is an excellent therapeutic option that is able to provide efficacious clearance of AKs as well as superior cosmetic outcomes. Common AEs of PDT include burning, itching, and stinging during therapy, but pain intensity decreases dramatically upon termination of illumination, with cessation of most symptoms by 12 hours posttherapy.⁷³ Permanent pigmentation changes have been reported to occasionally occur following PDT therapy.⁸¹

Conclusion

When determining which therapy to use in a patient, clinicians must take into account a variety of factors such as patient preference, cost of treatment, availability, tolerance for AEs, and the need for field therapy. Although all therapies discussed within this article are effective and reasonable treatment choices, patients who are particularly concerned about cosmetic outcomes would most likely benefit from either IMQ or PDT, as the data for cosmetic outcomes with these therapies are the strongest. Combination or sequential treatments may be required in some cases and all patients should be monitored for lesion recurrence regardless of treatment choice. A summary of the therapies and key studies discussed here is available in the PDF.

Actinic keratosis (AK), also referred to as solar keratosis or senile keratosis, is an intraepidermal proliferation of dysplastic keratinocytes that develops in response to chronic exposure to UV radiation. Actinic keratoses are among the most commonly encountered lesions seen by dermatologists, and it has been estimated that 60% of predisposed individuals older than 40 years have at least one AK.^1,2 Prevalence is notably higher in light-skinned individuals and increases with age, presumably from higher cumulative sun exposure and decreased effectiveness of the immune system.^1,3 It remains a point of contention as to whether or not AKs actually represent squamous cell carcinoma (SCC) in situ, but the potential for progression to invasive disease has been well demonstrated, as the majority of SCCs develop from preexisting AKs.^4-6 The risk for progression to invasive disease for an individual AK has been estimated to range from 0.025% to 16% per year, with an average of approximately 8% in immunocompetent patients.⁷

The clinical morphology of AK can vary widely, but the most common presentation is an erythematous scaly macule, papule, or plaque on sun-exposed skin. The skin surrounding AKs typically shows evidence of solar damage with deep wrinkling, mottled pigmentation, scattered telangiectases, purpura, or xerosis (Figure). A variety of clinical variants with unique presentations exist, including atrophic, hypertrophic, acantholytic, lichenoid, bowenoid, and pigmented subtypes. Because more than 80% of AKs occur on highly visible areas such as the head, neck, back of the hands, and forearms, AKs can have an obvious detrimental effect on cosmetic appearance. Studies also have shown a strong association between AKs and decreased overall quality of life (QOL).^3,8,9

Patient with numerous actinic keratoses, scattered plaques suspicious for squamous cell carcinoma, and numerous scars from prior squamous cell carcinoma treatments.

Topical Treatments

5-Fluorouracil

5-Fluorouracil (5-FU) is a US Food and Drug Administration (FDA)–approved, topically applied pyrimidine analogue that inhibits thymidylate synthase. The resulting suppression of DNA and RNA synthesis induces cell death with a preference for mitotically active cells.¹⁰ 5-Fluorouracil has been used for more than 
50 years as a treatment of AK and its efficacy is well established. A systematic review of 5 randomized controlled studies of topical 5-FU reported an average of 49% of 423 patients achieving complete lesion clearance with 5-FU cream 5% applied once or twice daily for up to 7 weeks.¹¹ Some notable drawbacks of 5-FU, however, are application-site erythema, blistering, pruritus, necrosis, erosion, and pain. These effects often lead to premature cessation of therapy, but newer formulations of 5-FU cream 0.5% have shown good efficacy with better tolerability.¹² A randomized, double-blind, multicenter, parallel-group study of 177 patients using 5-FU cream 0.5% once daily for either 1, 2, or 4 weeks demonstrated significant (P<.001) efficacy over vehicle gel in all treatment arms.¹³ The most effective therapy was 
4 weeks of treatment, which achieved a mean 91.7% reduction in lesion count as assessed 1 month after cessation of therapy. The primary adverse effect (AE) reported in this trial was mild to moderate facial irritation, which generally resolved within 
18 to 21 days after treatment cessation.¹³ Overall, 5-FU is a highly effective therapy for treating AKs that also can improve signs of photoaging, but patients should be aware of cosmetically unappealing effects that generally occur throughout therapy and during the immediate posttreatment period.¹⁴

Chemical Peels

Chemical peels traditionally employ acidic compounds to strip away outer layers of skin to variable depths depending on the concentration of the agent being applied. For treatment of AK, trichloroacetic acid (TCA) is a commonly employed cauterant that has shown efficacy comparable to topical 5-FU as well as ablative CO₂ laser resurfacing.¹⁵ Trichloroacetic acid peels also are a convenient therapy, as good results can be achieved after a single treatment session. A split-face study of 15 patients treated with either a single application of 35% TCA and Jessner solution or twice-daily application of 5-FU cream 5% for 3 weeks demonstrated a reduction in 75% of visible AKs in both treatment arms over a 1-year follow-up period.¹⁶ Although 80% of patients self-reported considerable cosmetic improvement with both therapies, patient preference was reported to be in favor of the TCA peel, given its quick results and relatively mild side effects as compared to 5-FU. Treatment with chemical peels will result in temporary erythema and mild desquamation that usually resolves within 2 weeks; however, there are cases in which erythema has been reported to persist for several months.¹⁶ Adverse effects such as permanent scarring or pigmentation changes rarely are seen with TCA concentrations less than 45%.¹⁷ Caution should be used in patients with a history of herpes simplex virus, keloids, postinflammatory hyperpigmentation, radiation exposure, immunosuppression, and those unable or unwilling to use sunscreen and avoid sun exposure in the immediate posttreatment period.

Diclofenac Sodium

Diclofenac sodium (DFS) is an FDA-approved topical, nonsteroidal, 
anti-inflammatory drug whose mechanism of action in the treatment of AK is thought to involve inhibition of the cyclooxygenase 2 enzyme.¹⁸ The resulting reduction of prostaglandins is believed to inhibit tumor angiogenesis, induce apoptosis, and inhibit cell differentiation.^19-22 In a multicenter, double-blind, placebo-controlled study of 195 patients, application of DFS 3% in hyaluronan gel 2.5% twice daily for 60 days showed significant (P<.05) efficacy over placebo in achieving complete resolution of target lesions during a 30-day follow-up period (31% vs 10%). Furthermore, qualitative patient assessment of complete global improvement also was significantly (P<.05) higher in the active treatment group as compared to placebo (31% vs 10%).²³ Additional studies of DFS 3% in hyaluronan gel 2.5% applied twice daily for 90 days have shown even higher rates of success, with complete resolution of target lesions in 40% to 58% of cases.^24,25 This therapy also has been reported to substantially improve QOL following treatment completion.²⁶ The most frequently cited AEs include pruritus, rash, dry skin, erythema, and application-site reactions. Overall, DFS is a 
well-tolerated therapy with efficacy comparable to that of 5-FU but with a lower incidence of AEs 
and higher patient satisfaction as determined in 
2 head-to-head studies.^27,28
ImiquimodImiquimod (IMQ) is an FDA-approved topical agent that functions as an immune response modifier via agonism of toll-like receptor 7.¹⁸ The resulting cytokine production and release enhances the innate and acquired immune responses leading to anticancer activity.²⁹ The efficacy of IMQ for treatment of AK has been demonstrated in numerous well-designed clinical trials. A 
meta-analysis of 5 randomized, double-blind trials including 1293 patients treated with IMQ cream 5% 
2 to 3 times per week for 12 to 16 weeks reported complete clearance of AKs in 50% of patients treated with IMQ as compared to 5% of patients treated with vehicle.³⁰ The most frequently reported AEs with this therapy include erythema, scabbing, flaking, and erosion. These effects generally resolve following cessation of treatment, and therapy is considered to be well tolerated; however, there are case reports of IMQ triggering or exacerbating existing inflammatory conditions.³¹ Imiquimod cream also is approved at 2.5% and 3.75% concentrations, which have demonstrated significant (P<.001) efficacy over placebo and a reduced incidence of AEs; complete clearance rates have been reported as 30.6% and 35.6%, respectively.³² Notably, a study comparing 75 patients randomized to either IMQ cream 5% 
3 times per week for 4 weeks, 1 or 2 courses of cryosurgery, or 5-FU ointment 5% twice daily for 4 weeks reported that IMQ achieved significantly (P<.01) superior sustained clearance rates during a 12-month follow-up period over cryosurgery and 5-FU 
(73% vs 4% vs 33%).³³ Additionally, cosmetic outcomes as determined by both participants and investigators were reported as excellent at 12 months posttreatment in more than 80% of participants treated with IMQ. These excellent, long-lasting cosmetic outcomes also were determined to be significantly (P<.0001) superior to the cosmetic outcomes of 5-FU and cryotherapy, which both reported excellent outcomes in less than 10% of cases.³³
Ingenol MebutateIngenol mebutate (IM) is a macrocyclic diterpene ester derived from the Euphorbia peplus plant that is FDA approved for the treatment of AK.¹ Ingenol mebutate’s mechanism of action is thought to involve induction of cell death via disruption of the plasma membrane and mitochondria in addition to production of an inflammatory response, which produces tumor-specific antibodies and a large influx of neutrophils.^34,35 The overall evidence for the efficacy of IM is strong. A combined analysis of 4 multicenter, randomized, double-blind studies of 1005 participants reported that IM gel 0.015% applied once daily for 3 days to the face or scalp was significantly superior (P<.001) to placebo in achieving complete clearance as assessed 54 days after completion of therapy (42.2% vs 3.7%) and that IM gel 0.05% applied once daily for 2 days to the trunk or extremities also was significantly superior (P<.001) to placebo in achieving complete clearance as determined 55 days after completion of therapy (34.1% vs 4.7%).³⁶ A follow-up report to this study indicated that IM also appears to achieve long-lasting effects with an overall 87% decrease in total AKs at 12 months follow-up in both trial groups.³⁷ Additionally, it has been recently reported that treatment with IM in these trials was associated with significantly higher overall treatment satisfaction (P<.001) and improved QOL (P<.001) as compared to vehicle.³⁸ Cosmetic outcomes of IM therapy have been assessed in a trial analyzing the efficacy of IM gel 0.025% for 3 days or IM gel 0.05% for 2 or 3 days on nonfacial AKs. This study reported significantly (P<.0001) higher patient satisfaction with the cosmetic outcome at 8 weeks after therapy as compared to vehicle.³⁴ Studies performed in mice have demonstrated that IM is able to promote collagen matrix turnover and impose dermal elasticity, which may contribute to these good cosmetic outcomes.³⁹ The most common AEs of IM therapy are erythema, crusting, and flaking; these effects generally occur 3 to 8 days after starting treatment. These effects, however, generally are short lived and resolve within 2 weeks of treatment cessation when IM is applied to the face or scalp or 4 weeks when applied to the trunk or extremities.⁴⁰ Overall, IM is a useful therapeutic option given its relatively short treatment course as compared to other topically applied agents, as well as its lasting efficacy, mild AEs, and good cosmetic outcomes.

Procedural Modalities

Surgical Procedures

Surgical approaches for the treatment of AK include excision, curettage with or without electrodesiccation, and dermabrasion. In the past, these modalities were used with greater frequency, but the advent of effective topical medications with lower risks of AEs has largely reduced their use.⁴¹ Excision may still be indicated in cases where SCC is suspected, and curettage can be used for treatment of thicker hypertrophic AKs.⁴² Although these approaches have not been evaluated in clinical trials, they are generally effective but require the use of local anesthetics and come with substantial risk for infection, permanent scarring, and hypopigmentation. Dermabrasion employs the use of a motorized device equipped with an abrasive material to physically remove superficial layers of the skin. Studies are limited, but this method has been reported as an effective treatment in a retrospective review of 23 participants in which 96% remained free of AKs at 1 year, 83% at 2 years, 64% at 4 years, and 54% at 5 years posttherapy.⁴³ Notably, one split-face study of 40 participants treated with dermabrasion followed by 25% TCA on one side and either Jessner solution and 35% TCA or dermabrasion alone on the other side reported that the combination of dermabrasion with 25% TCA consistently produced excellent cosmetic results with nearly complete eradication of AKs.⁴⁴ In general, however, cosmetic outcomes with dermabrasion are variable, as the technique is highly operator dependent and treatment is associated with notable discomfort as well as risk for scarring and permanent pigmentation alteration.

Cryotherapy

Cryotherapy remains one of the most commonly utilized treatments of AK and involves the delivery of liquid nitrogen via a spray device or a cotton tip applicator to rapidly freeze cells, thus causing cellular destruction via ice crystal formation and protein denaturation.⁴⁵ Efficacy with this technique has been reported to be as high as 98.8% at 12 months follow-up, but more recent studies cite lower rates of success.⁴⁶ A prospective multicenter study of 90 participants with 421 AKs on the face or scalp treated with a single freeze-thaw cycle of liquid nitrogen reported an overall complete response rate of 67.2% at 3 months posttherapy. Additionally, higher complete response rates were associated with longer freeze times, and cosmetic outcomes were reported as good to excellent in 94% of complete response lesions.⁴⁷ Similar results were reported in an open-label, prospective, randomized, controlled clinical trial of 200 participants with 
543 AKs, which compared a single freeze-thaw cycle with liquid nitrogen to a single session of CO₂ laser ablation in the treatment of isolated AKs of the face and scalp.⁴⁸ At 3 months posttherapy, complete clearance was observed in 71.6% of participants treated with cryotherapy and in 65.3% of participants treated with laser ablation (P=.532). At 
12 months posttherapy, participants who originally showed complete response at 3 months were assessed for relapse. Complete clearance was preserved in 72.6% of participants treated with cryotherapy versus 21.9% of participants treated with laser ablation (P<.0001), and cosmetic outcomes were reported by participants as good or excellent at 3 months follow-up in more than 93% of participants for both treatment arms.⁴⁸ Possible AEs of cryotherapy include pain during treatment, blister formation with possible hemorrhage, infection, scarring, and permanent pigmentary changes.^47,48 Notably, the risk for hypopigmentation increases with longer freezing times, thus requiring clinicians to consider the balance between improved efficacy and reduced cosmetic outcomes.⁴⁷

Light-Based Therapies

Laser Therapy

Ablative laser resurfacing with either the CO₂ or erbium-doped:YAG (Er:YAG) laser utilizes light of specific wavelengths to selectively induce thermolysis and destruction of the epidermal layer. Both lasers have been studied as treatments of AK, but there is a lack of large, well-designed studies. In one small study of 14 participants treated with 
1 to 2 passes of the CO₂ laser, complete clearance was reported in all cases without any recurrences during a follow-up period of 6 to 24 months. Additionally, all participants in this study reported satisfaction with the cosmetic outcome.⁴⁹ The CO₂ laser also has demonstrated efficacy comparable to that of the TCA peel and 5-FU therapy in a prospective randomized trial of 34 patients with facial or scalp AKs who received either CO₂ laser with 2 passes, 30% TCA peel, or 5-FU cream 5% twice daily for 
3 weeks.¹⁵ Reduction in mean AK counts at 3 months posttherapy was significantly (P<.03) higher in all treatment arms as compared to the control group (92% for CO₂ laser, 89% for TCA peel, and 83% for 5-FU cream). No significant (P=.31) difference in outcomes was noted among the different treatment arms.¹⁵ Similar results were reported for the Er:YAG laser in a small prospective study of 5 participants treated with 2 to 3 passes with the Er:YAG laser in which reduction in mean AK counts was reported as ranging from 86% to 96% at 3 months posttherapy.⁵⁰ The Er:YAG laser in combination with the CO₂ laser has shown notable long-term efficacy in achieving higher lesion clearance rates and sustained complete clearance rates over treatment with topical 5-FU.⁵¹ In a prospective randomized study of 55 par-ticipants with multiple AKs on the face or scalp, participants were assigned to receive either combination laser ablation with the Er:YAG and CO₂ lasers down to the level of the papillary dermis or 
5-FU cream 5% applied twice daily for 2 to 7 weeks until an appropriate clinical inflammatory response was achieved. At 12 months follow-up, the laser treatment group achieved significantly (P=.048) higher mean lesion clearance rates (91.1%) as compared to the 5-FU arm (76.6%) and significantly (P=.003) higher sustained complete clearance rates (59.3%) as compared to 5-FU (29.2%). The proportion of participants with an improvement in photoaging score at 12 months follow-up approached statistical significance (P=.07), with 74% of the laser-treated group showing improvement as compared to 43% of the 5-FU–treated group. Long-term, cosmetically unappealing side effects such as erythema and hypopigmentation occurred notably more often in the laser-treated group as compared to the 5-FU group.⁵¹ In summary, ablative lasers appear to be a highly effective therapy for AK but at the cost of increased risk for AEs such as permanent pigmentary changes, prolonged erythema lasting up to several months, and scarring.^50,52-55

Fractional photothermolysis is a relatively new advancement in the field of laser therapy that has received FDA approval for the treatment of AK.⁵⁶ This treatment works by creating multiple noncontiguous microscopic columns of thermal injury while sparing adjacent zones of viable tissue.⁵⁷ Although there are limited studies involving the use of such lasers in the treatment of AK, initial findings suggest that 1927-nm thulium lasers may be more effective than 1550-nm erbium lasers in achieving lesion clearance. A trial of 14 participants who received 5 laser treatments with a 1550-nm fractionated erbium-doped fiber laser reported an average reduction in AK counts of 66.2% at 3 months follow-up and a 55.6% reduction at 6 months follow-up. A participant-determined marked or very significant improvement of lesions was reported in 83% of participants at 1 month posttreatment but only in 44% of participants at 6 months posttreatment.⁵⁸ A similar trial of 24 participants treated with up to 4 treatment sessions of the fractionated 1927-nm thulium laser reported an 87.3% reduction in number of AKs at 3 months follow-up and an 86.6% reduction at 
6 months follow-up.⁵⁶ The primary advantage of fractional laser therapy is a faster recovery period generally lasting only 2 or 3 days as compared to 
2 weeks or more with traditional ablative lasers, thus limiting the amount of time a patient must tolerate cosmetically unappealing erythema.^59,60 The quick recovery time has been attributed to the fractional laser’s ability to preserve the stratum corneum and skin barrier, which also helps reduce the risk for other AEs such as scarring and infection.^56,59-61 Additional studies are needed to better assess the true efficacy of fractional laser therapy, but treatment with the fractional 1927-nm thulium laser appears to be a promising and well-tolerated therapeutic option for treatment of AK with similar efficacy to traditional ablative lasers but with a lower risk of AEs.

Photodynamic TherapyPhotodynamic therapy (PDT) is an FDA-approved treatment that involves the use of a topical photosensitizing agent such as 5-aminolevulinic acid (ALA) or methyl aminovulinate (MAL) before exposure to an activating light source to generate reactive oxygen species that lead to cell death.^62-65 Multiple PDT regimens with varying combinations of photosensitizers, incubation time, and light sources have been studied, but a 
2012 Cochrane review determined that treatment with conventional formulations of MAL and ALA with either blue- or red-light PDT were similarly efficacious for treatment of individual AKs as compared to vehicle with blue- or red-light PDT. One exception was that longer incubation time (ie, 4 hours) with ALA resulted in better results than shorter incubation times (ie, 0.5, 1, 2 hours) with ALA.⁶⁶

Standard PDT treatment with MAL also has consistently demonstrated superior efficacy in achieving complete clearance rates in addition to superior cosmetic outcomes over treatment with either cryotherapy, DFS, or 5-FU.^67-73 Three studies in particular noted an excellent or good investigator-determined cosmetic outcome in 96% to 98% of participants treated with MAL-PDT.^69,71,74 Photodynamic therapy with ALA also has been reported as superior over CO2 laser ablation for AK reduction as well as both patient and investigator overall satisfaction.⁷⁵

More recently, several methods of improving photosensitizer delivery have been studied, which have demonstrated remarkable efficacy at achieving lesion clearance over standard cream formulations or application routines. One such method involves the use of gentle heating to increase photosensitizer uptake. In a split-extremity study of 20 participants who were treated with 20% ALA under occlusion for 1 hour with one side heated to 38.8°C, the heated side demonstrated significant (P<.0001) efficacy at achieving higher median clearance rates over control when evaluated at 2 and 6 months posttherapy.⁷⁶ Notably, occlusion of ALA in itself during the incubation period also has been demonstrated to significantly (P<.0001) improve clearance rates.⁷⁷ Another method involves the use of a new nanoemulsion-based formulation of 
ALA gel, known as BF-200 ALA, which has demonstrated remarkable efficacy over standard 
MAL cream and placebo in a long-term follow-up 
analysis of 2 prospective, randomized, controlled trials.⁷⁸ In a similar vein, 3 prospective randomized trials with a minimum follow-up time of 3 months demonstrated that MAL-PDT in combination with fractional ablative laser pretreatment has significant (P<.02 in all trials) efficacy over MAL-PDT without pretreatment in achieving complete AK clearance. Although the cosmetic outcomes were good or excellent in 87% to 100% of patients, they were not significantly different from stand-alone 
MAL-PDT treatment in any of the trials.^79-81 However, pretreatment with microneedling in MAL-PDT has been shown to achieve superior cosmetic outcomes over 
MAL-PDT without microneedling, according to one small split-face study of 10 participants.⁸²

Overall, PDT is an excellent therapeutic option that is able to provide efficacious clearance of AKs as well as superior cosmetic outcomes. Common AEs of PDT include burning, itching, and stinging during therapy, but pain intensity decreases dramatically upon termination of illumination, with cessation of most symptoms by 12 hours posttherapy.⁷³ Permanent pigmentation changes have been reported to occasionally occur following PDT therapy.⁸¹

Conclusion

When determining which therapy to use in a patient, clinicians must take into account a variety of factors such as patient preference, cost of treatment, availability, tolerance for AEs, and the need for field therapy. Although all therapies discussed within this article are effective and reasonable treatment choices, patients who are particularly concerned about cosmetic outcomes would most likely benefit from either IMQ or PDT, as the data for cosmetic outcomes with these therapies are the strongest. Combination or sequential treatments may be required in some cases and all patients should be monitored for lesion recurrence regardless of treatment choice. A summary of the therapies and key studies discussed here is available in the PDF.

Actinic keratosis (AK), also referred to as solar keratosis or senile keratosis, is an intraepidermal proliferation of dysplastic keratinocytes that develops in response to chronic exposure to UV radiation. Actinic keratoses are among the most commonly encountered lesions seen by dermatologists, and it has been estimated that 60% of predisposed individuals older than 40 years have at least one AK.^1,2 Prevalence is notably higher in light-skinned individuals and increases with age, presumably from higher cumulative sun exposure and decreased effectiveness of the immune system.^1,3 It remains a point of contention as to whether or not AKs actually represent squamous cell carcinoma (SCC) in situ, but the potential for progression to invasive disease has been well demonstrated, as the majority of SCCs develop from preexisting AKs.^4-6 The risk for progression to invasive disease for an individual AK has been estimated to range from 0.025% to 16% per year, with an average of approximately 8% in immunocompetent patients.⁷

The clinical morphology of AK can vary widely, but the most common presentation is an erythematous scaly macule, papule, or plaque on sun-exposed skin. The skin surrounding AKs typically shows evidence of solar damage with deep wrinkling, mottled pigmentation, scattered telangiectases, purpura, or xerosis (Figure). A variety of clinical variants with unique presentations exist, including atrophic, hypertrophic, acantholytic, lichenoid, bowenoid, and pigmented subtypes. Because more than 80% of AKs occur on highly visible areas such as the head, neck, back of the hands, and forearms, AKs can have an obvious detrimental effect on cosmetic appearance. Studies also have shown a strong association between AKs and decreased overall quality of life (QOL).^3,8,9

Patient with numerous actinic keratoses, scattered plaques suspicious for squamous cell carcinoma, and numerous scars from prior squamous cell carcinoma treatments.

Topical Treatments

5-Fluorouracil

5-Fluorouracil (5-FU) is a US Food and Drug Administration (FDA)–approved, topically applied pyrimidine analogue that inhibits thymidylate synthase. The resulting suppression of DNA and RNA synthesis induces cell death with a preference for mitotically active cells.¹⁰ 5-Fluorouracil has been used for more than 
50 years as a treatment of AK and its efficacy is well established. A systematic review of 5 randomized controlled studies of topical 5-FU reported an average of 49% of 423 patients achieving complete lesion clearance with 5-FU cream 5% applied once or twice daily for up to 7 weeks.¹¹ Some notable drawbacks of 5-FU, however, are application-site erythema, blistering, pruritus, necrosis, erosion, and pain. These effects often lead to premature cessation of therapy, but newer formulations of 5-FU cream 0.5% have shown good efficacy with better tolerability.¹² A randomized, double-blind, multicenter, parallel-group study of 177 patients using 5-FU cream 0.5% once daily for either 1, 2, or 4 weeks demonstrated significant (P<.001) efficacy over vehicle gel in all treatment arms.¹³ The most effective therapy was 
4 weeks of treatment, which achieved a mean 91.7% reduction in lesion count as assessed 1 month after cessation of therapy. The primary adverse effect (AE) reported in this trial was mild to moderate facial irritation, which generally resolved within 
18 to 21 days after treatment cessation.¹³ Overall, 5-FU is a highly effective therapy for treating AKs that also can improve signs of photoaging, but patients should be aware of cosmetically unappealing effects that generally occur throughout therapy and during the immediate posttreatment period.¹⁴

Chemical Peels

Chemical peels traditionally employ acidic compounds to strip away outer layers of skin to variable depths depending on the concentration of the agent being applied. For treatment of AK, trichloroacetic acid (TCA) is a commonly employed cauterant that has shown efficacy comparable to topical 5-FU as well as ablative CO₂ laser resurfacing.¹⁵ Trichloroacetic acid peels also are a convenient therapy, as good results can be achieved after a single treatment session. A split-face study of 15 patients treated with either a single application of 35% TCA and Jessner solution or twice-daily application of 5-FU cream 5% for 3 weeks demonstrated a reduction in 75% of visible AKs in both treatment arms over a 1-year follow-up period.¹⁶ Although 80% of patients self-reported considerable cosmetic improvement with both therapies, patient preference was reported to be in favor of the TCA peel, given its quick results and relatively mild side effects as compared to 5-FU. Treatment with chemical peels will result in temporary erythema and mild desquamation that usually resolves within 2 weeks; however, there are cases in which erythema has been reported to persist for several months.¹⁶ Adverse effects such as permanent scarring or pigmentation changes rarely are seen with TCA concentrations less than 45%.¹⁷ Caution should be used in patients with a history of herpes simplex virus, keloids, postinflammatory hyperpigmentation, radiation exposure, immunosuppression, and those unable or unwilling to use sunscreen and avoid sun exposure in the immediate posttreatment period.

Diclofenac Sodium

Diclofenac sodium (DFS) is an FDA-approved topical, nonsteroidal, 
anti-inflammatory drug whose mechanism of action in the treatment of AK is thought to involve inhibition of the cyclooxygenase 2 enzyme.¹⁸ The resulting reduction of prostaglandins is believed to inhibit tumor angiogenesis, induce apoptosis, and inhibit cell differentiation.^19-22 In a multicenter, double-blind, placebo-controlled study of 195 patients, application of DFS 3% in hyaluronan gel 2.5% twice daily for 60 days showed significant (P<.05) efficacy over placebo in achieving complete resolution of target lesions during a 30-day follow-up period (31% vs 10%). Furthermore, qualitative patient assessment of complete global improvement also was significantly (P<.05) higher in the active treatment group as compared to placebo (31% vs 10%).²³ Additional studies of DFS 3% in hyaluronan gel 2.5% applied twice daily for 90 days have shown even higher rates of success, with complete resolution of target lesions in 40% to 58% of cases.^24,25 This therapy also has been reported to substantially improve QOL following treatment completion.²⁶ The most frequently cited AEs include pruritus, rash, dry skin, erythema, and application-site reactions. Overall, DFS is a 
well-tolerated therapy with efficacy comparable to that of 5-FU but with a lower incidence of AEs 
and higher patient satisfaction as determined in 
2 head-to-head studies.^27,28
ImiquimodImiquimod (IMQ) is an FDA-approved topical agent that functions as an immune response modifier via agonism of toll-like receptor 7.¹⁸ The resulting cytokine production and release enhances the innate and acquired immune responses leading to anticancer activity.²⁹ The efficacy of IMQ for treatment of AK has been demonstrated in numerous well-designed clinical trials. A 
meta-analysis of 5 randomized, double-blind trials including 1293 patients treated with IMQ cream 5% 
2 to 3 times per week for 12 to 16 weeks reported complete clearance of AKs in 50% of patients treated with IMQ as compared to 5% of patients treated with vehicle.³⁰ The most frequently reported AEs with this therapy include erythema, scabbing, flaking, and erosion. These effects generally resolve following cessation of treatment, and therapy is considered to be well tolerated; however, there are case reports of IMQ triggering or exacerbating existing inflammatory conditions.³¹ Imiquimod cream also is approved at 2.5% and 3.75% concentrations, which have demonstrated significant (P<.001) efficacy over placebo and a reduced incidence of AEs; complete clearance rates have been reported as 30.6% and 35.6%, respectively.³² Notably, a study comparing 75 patients randomized to either IMQ cream 5% 
3 times per week for 4 weeks, 1 or 2 courses of cryosurgery, or 5-FU ointment 5% twice daily for 4 weeks reported that IMQ achieved significantly (P<.01) superior sustained clearance rates during a 12-month follow-up period over cryosurgery and 5-FU 
(73% vs 4% vs 33%).³³ Additionally, cosmetic outcomes as determined by both participants and investigators were reported as excellent at 12 months posttreatment in more than 80% of participants treated with IMQ. These excellent, long-lasting cosmetic outcomes also were determined to be significantly (P<.0001) superior to the cosmetic outcomes of 5-FU and cryotherapy, which both reported excellent outcomes in less than 10% of cases.³³
Ingenol MebutateIngenol mebutate (IM) is a macrocyclic diterpene ester derived from the Euphorbia peplus plant that is FDA approved for the treatment of AK.¹ Ingenol mebutate’s mechanism of action is thought to involve induction of cell death via disruption of the plasma membrane and mitochondria in addition to production of an inflammatory response, which produces tumor-specific antibodies and a large influx of neutrophils.^34,35 The overall evidence for the efficacy of IM is strong. A combined analysis of 4 multicenter, randomized, double-blind studies of 1005 participants reported that IM gel 0.015% applied once daily for 3 days to the face or scalp was significantly superior (P<.001) to placebo in achieving complete clearance as assessed 54 days after completion of therapy (42.2% vs 3.7%) and that IM gel 0.05% applied once daily for 2 days to the trunk or extremities also was significantly superior (P<.001) to placebo in achieving complete clearance as determined 55 days after completion of therapy (34.1% vs 4.7%).³⁶ A follow-up report to this study indicated that IM also appears to achieve long-lasting effects with an overall 87% decrease in total AKs at 12 months follow-up in both trial groups.³⁷ Additionally, it has been recently reported that treatment with IM in these trials was associated with significantly higher overall treatment satisfaction (P<.001) and improved QOL (P<.001) as compared to vehicle.³⁸ Cosmetic outcomes of IM therapy have been assessed in a trial analyzing the efficacy of IM gel 0.025% for 3 days or IM gel 0.05% for 2 or 3 days on nonfacial AKs. This study reported significantly (P<.0001) higher patient satisfaction with the cosmetic outcome at 8 weeks after therapy as compared to vehicle.³⁴ Studies performed in mice have demonstrated that IM is able to promote collagen matrix turnover and impose dermal elasticity, which may contribute to these good cosmetic outcomes.³⁹ The most common AEs of IM therapy are erythema, crusting, and flaking; these effects generally occur 3 to 8 days after starting treatment. These effects, however, generally are short lived and resolve within 2 weeks of treatment cessation when IM is applied to the face or scalp or 4 weeks when applied to the trunk or extremities.⁴⁰ Overall, IM is a useful therapeutic option given its relatively short treatment course as compared to other topically applied agents, as well as its lasting efficacy, mild AEs, and good cosmetic outcomes.

Procedural Modalities

Surgical Procedures

Surgical approaches for the treatment of AK include excision, curettage with or without electrodesiccation, and dermabrasion. In the past, these modalities were used with greater frequency, but the advent of effective topical medications with lower risks of AEs has largely reduced their use.⁴¹ Excision may still be indicated in cases where SCC is suspected, and curettage can be used for treatment of thicker hypertrophic AKs.⁴² Although these approaches have not been evaluated in clinical trials, they are generally effective but require the use of local anesthetics and come with substantial risk for infection, permanent scarring, and hypopigmentation. Dermabrasion employs the use of a motorized device equipped with an abrasive material to physically remove superficial layers of the skin. Studies are limited, but this method has been reported as an effective treatment in a retrospective review of 23 participants in which 96% remained free of AKs at 1 year, 83% at 2 years, 64% at 4 years, and 54% at 5 years posttherapy.⁴³ Notably, one split-face study of 40 participants treated with dermabrasion followed by 25% TCA on one side and either Jessner solution and 35% TCA or dermabrasion alone on the other side reported that the combination of dermabrasion with 25% TCA consistently produced excellent cosmetic results with nearly complete eradication of AKs.⁴⁴ In general, however, cosmetic outcomes with dermabrasion are variable, as the technique is highly operator dependent and treatment is associated with notable discomfort as well as risk for scarring and permanent pigmentation alteration.

Cryotherapy

Cryotherapy remains one of the most commonly utilized treatments of AK and involves the delivery of liquid nitrogen via a spray device or a cotton tip applicator to rapidly freeze cells, thus causing cellular destruction via ice crystal formation and protein denaturation.⁴⁵ Efficacy with this technique has been reported to be as high as 98.8% at 12 months follow-up, but more recent studies cite lower rates of success.⁴⁶ A prospective multicenter study of 90 participants with 421 AKs on the face or scalp treated with a single freeze-thaw cycle of liquid nitrogen reported an overall complete response rate of 67.2% at 3 months posttherapy. Additionally, higher complete response rates were associated with longer freeze times, and cosmetic outcomes were reported as good to excellent in 94% of complete response lesions.⁴⁷ Similar results were reported in an open-label, prospective, randomized, controlled clinical trial of 200 participants with 
543 AKs, which compared a single freeze-thaw cycle with liquid nitrogen to a single session of CO₂ laser ablation in the treatment of isolated AKs of the face and scalp.⁴⁸ At 3 months posttherapy, complete clearance was observed in 71.6% of participants treated with cryotherapy and in 65.3% of participants treated with laser ablation (P=.532). At 
12 months posttherapy, participants who originally showed complete response at 3 months were assessed for relapse. Complete clearance was preserved in 72.6% of participants treated with cryotherapy versus 21.9% of participants treated with laser ablation (P<.0001), and cosmetic outcomes were reported by participants as good or excellent at 3 months follow-up in more than 93% of participants for both treatment arms.⁴⁸ Possible AEs of cryotherapy include pain during treatment, blister formation with possible hemorrhage, infection, scarring, and permanent pigmentary changes.^47,48 Notably, the risk for hypopigmentation increases with longer freezing times, thus requiring clinicians to consider the balance between improved efficacy and reduced cosmetic outcomes.⁴⁷

Light-Based Therapies

Laser Therapy

Ablative laser resurfacing with either the CO₂ or erbium-doped:YAG (Er:YAG) laser utilizes light of specific wavelengths to selectively induce thermolysis and destruction of the epidermal layer. Both lasers have been studied as treatments of AK, but there is a lack of large, well-designed studies. In one small study of 14 participants treated with 
1 to 2 passes of the CO₂ laser, complete clearance was reported in all cases without any recurrences during a follow-up period of 6 to 24 months. Additionally, all participants in this study reported satisfaction with the cosmetic outcome.⁴⁹ The CO₂ laser also has demonstrated efficacy comparable to that of the TCA peel and 5-FU therapy in a prospective randomized trial of 34 patients with facial or scalp AKs who received either CO₂ laser with 2 passes, 30% TCA peel, or 5-FU cream 5% twice daily for 
3 weeks.¹⁵ Reduction in mean AK counts at 3 months posttherapy was significantly (P<.03) higher in all treatment arms as compared to the control group (92% for CO₂ laser, 89% for TCA peel, and 83% for 5-FU cream). No significant (P=.31) difference in outcomes was noted among the different treatment arms.¹⁵ Similar results were reported for the Er:YAG laser in a small prospective study of 5 participants treated with 2 to 3 passes with the Er:YAG laser in which reduction in mean AK counts was reported as ranging from 86% to 96% at 3 months posttherapy.⁵⁰ The Er:YAG laser in combination with the CO₂ laser has shown notable long-term efficacy in achieving higher lesion clearance rates and sustained complete clearance rates over treatment with topical 5-FU.⁵¹ In a prospective randomized study of 55 par-ticipants with multiple AKs on the face or scalp, participants were assigned to receive either combination laser ablation with the Er:YAG and CO₂ lasers down to the level of the papillary dermis or 
5-FU cream 5% applied twice daily for 2 to 7 weeks until an appropriate clinical inflammatory response was achieved. At 12 months follow-up, the laser treatment group achieved significantly (P=.048) higher mean lesion clearance rates (91.1%) as compared to the 5-FU arm (76.6%) and significantly (P=.003) higher sustained complete clearance rates (59.3%) as compared to 5-FU (29.2%). The proportion of participants with an improvement in photoaging score at 12 months follow-up approached statistical significance (P=.07), with 74% of the laser-treated group showing improvement as compared to 43% of the 5-FU–treated group. Long-term, cosmetically unappealing side effects such as erythema and hypopigmentation occurred notably more often in the laser-treated group as compared to the 5-FU group.⁵¹ In summary, ablative lasers appear to be a highly effective therapy for AK but at the cost of increased risk for AEs such as permanent pigmentary changes, prolonged erythema lasting up to several months, and scarring.^50,52-55

Fractional photothermolysis is a relatively new advancement in the field of laser therapy that has received FDA approval for the treatment of AK.⁵⁶ This treatment works by creating multiple noncontiguous microscopic columns of thermal injury while sparing adjacent zones of viable tissue.⁵⁷ Although there are limited studies involving the use of such lasers in the treatment of AK, initial findings suggest that 1927-nm thulium lasers may be more effective than 1550-nm erbium lasers in achieving lesion clearance. A trial of 14 participants who received 5 laser treatments with a 1550-nm fractionated erbium-doped fiber laser reported an average reduction in AK counts of 66.2% at 3 months follow-up and a 55.6% reduction at 6 months follow-up. A participant-determined marked or very significant improvement of lesions was reported in 83% of participants at 1 month posttreatment but only in 44% of participants at 6 months posttreatment.⁵⁸ A similar trial of 24 participants treated with up to 4 treatment sessions of the fractionated 1927-nm thulium laser reported an 87.3% reduction in number of AKs at 3 months follow-up and an 86.6% reduction at 
6 months follow-up.⁵⁶ The primary advantage of fractional laser therapy is a faster recovery period generally lasting only 2 or 3 days as compared to 
2 weeks or more with traditional ablative lasers, thus limiting the amount of time a patient must tolerate cosmetically unappealing erythema.^59,60 The quick recovery time has been attributed to the fractional laser’s ability to preserve the stratum corneum and skin barrier, which also helps reduce the risk for other AEs such as scarring and infection.^56,59-61 Additional studies are needed to better assess the true efficacy of fractional laser therapy, but treatment with the fractional 1927-nm thulium laser appears to be a promising and well-tolerated therapeutic option for treatment of AK with similar efficacy to traditional ablative lasers but with a lower risk of AEs.

Photodynamic TherapyPhotodynamic therapy (PDT) is an FDA-approved treatment that involves the use of a topical photosensitizing agent such as 5-aminolevulinic acid (ALA) or methyl aminovulinate (MAL) before exposure to an activating light source to generate reactive oxygen species that lead to cell death.^62-65 Multiple PDT regimens with varying combinations of photosensitizers, incubation time, and light sources have been studied, but a 
2012 Cochrane review determined that treatment with conventional formulations of MAL and ALA with either blue- or red-light PDT were similarly efficacious for treatment of individual AKs as compared to vehicle with blue- or red-light PDT. One exception was that longer incubation time (ie, 4 hours) with ALA resulted in better results than shorter incubation times (ie, 0.5, 1, 2 hours) with ALA.⁶⁶

Standard PDT treatment with MAL also has consistently demonstrated superior efficacy in achieving complete clearance rates in addition to superior cosmetic outcomes over treatment with either cryotherapy, DFS, or 5-FU.^67-73 Three studies in particular noted an excellent or good investigator-determined cosmetic outcome in 96% to 98% of participants treated with MAL-PDT.^69,71,74 Photodynamic therapy with ALA also has been reported as superior over CO2 laser ablation for AK reduction as well as both patient and investigator overall satisfaction.⁷⁵

More recently, several methods of improving photosensitizer delivery have been studied, which have demonstrated remarkable efficacy at achieving lesion clearance over standard cream formulations or application routines. One such method involves the use of gentle heating to increase photosensitizer uptake. In a split-extremity study of 20 participants who were treated with 20% ALA under occlusion for 1 hour with one side heated to 38.8°C, the heated side demonstrated significant (P<.0001) efficacy at achieving higher median clearance rates over control when evaluated at 2 and 6 months posttherapy.⁷⁶ Notably, occlusion of ALA in itself during the incubation period also has been demonstrated to significantly (P<.0001) improve clearance rates.⁷⁷ Another method involves the use of a new nanoemulsion-based formulation of 
ALA gel, known as BF-200 ALA, which has demonstrated remarkable efficacy over standard 
MAL cream and placebo in a long-term follow-up 
analysis of 2 prospective, randomized, controlled trials.⁷⁸ In a similar vein, 3 prospective randomized trials with a minimum follow-up time of 3 months demonstrated that MAL-PDT in combination with fractional ablative laser pretreatment has significant (P<.02 in all trials) efficacy over MAL-PDT without pretreatment in achieving complete AK clearance. Although the cosmetic outcomes were good or excellent in 87% to 100% of patients, they were not significantly different from stand-alone 
MAL-PDT treatment in any of the trials.^79-81 However, pretreatment with microneedling in MAL-PDT has been shown to achieve superior cosmetic outcomes over 
MAL-PDT without microneedling, according to one small split-face study of 10 participants.⁸²

Overall, PDT is an excellent therapeutic option that is able to provide efficacious clearance of AKs as well as superior cosmetic outcomes. Common AEs of PDT include burning, itching, and stinging during therapy, but pain intensity decreases dramatically upon termination of illumination, with cessation of most symptoms by 12 hours posttherapy.⁷³ Permanent pigmentation changes have been reported to occasionally occur following PDT therapy.⁸¹

Conclusion

When determining which therapy to use in a patient, clinicians must take into account a variety of factors such as patient preference, cost of treatment, availability, tolerance for AEs, and the need for field therapy. Although all therapies discussed within this article are effective and reasonable treatment choices, patients who are particularly concerned about cosmetic outcomes would most likely benefit from either IMQ or PDT, as the data for cosmetic outcomes with these therapies are the strongest. Combination or sequential treatments may be required in some cases and all patients should be monitored for lesion recurrence regardless of treatment choice. A summary of the therapies and key studies discussed here is available in the PDF.

The introduction of high-density radiation electronic brachytherapy (eBX) for the treatment of nonmelanoma skin cancers has induced great angst within the dermatology community.¹ The Current Procedural Terminology (CPT) code 0182T (high dose rate eBX) reimburses at an extraordinarily high rate, which has drawn a substantial amount of attention. Some critics see it as another case of overutilization, of sucking more money out of a bleeding Medicare system. The financial opportunity afforded by eBX has even led some entrepreneurs to purchase dermatology clinics so that skin cancer patients can be treated via this modality instead of more traditional and less costly techniques (personal communication, 2014).

Among radiation oncologists, high-density radiation eBX is considered to be an important treatment option for select patients who have skin cancers staged as T1 or T2 tumors that are 4 cm or smaller in diameter and 5 mm or less in depth.² Additionally, ideal candidates for nonsurgical treatment options such as eBX include patients with lesions in cosmetically challenging areas (eg, ears, nose), those who may experience problematic wound healing due to tumor location (eg, lower extremities) or medical conditions (eg, diabetes mellitus, peripheral vascular disease), those with medical comorbidities that may preclude them from surgery, those currently taking anticoagulants, and those who are not interested in undergoing surgery.

A common criticism of eBX is that there is little data on long-term treatment outcomes, which will soon be addressed by a 5-year multicenter, prospective, randomized study of 720 patients with basal cell carcinoma and squamous cell carcinoma led by the University of California, Irvine, and the University of California, San Diego (study protocol currently with institutional review board). Another criticism is that some manufacturers of eBX devices gained the less rigorous US Food and Drug Administration Premarket Notification 510(k) certification; however, this certification is quite commonplace in the United States, and an examination of the data actually shows a lower recall rate with this method when compared to the longer premarket approval application process.³ A more important criticism of eBX might be that radiation therapy is associated with a substantial increase in skin cancers that may occur decades later in irradiated areas; however, there remains a paucity of studies examining the safety data on eBX during the posttreatment period when such effects would be expected.

In practice, the forces for good and evil are not only limited to those who utilize eBX. It is widely known that CPT codes for Mohs micrographic surgery also have been abused—that is, the procedure has been used in circumstances where it was not absolutely necessary⁴—which led to an effort by dermatologic surgery organizations to agree on appropriate use criteria for Mohs surgery.⁵ These criteria are not perfect but should help curb the misuse of a valuable technique, which is one that is recognized as being optimal for the treatment of complex skin cancers. One might suggest forming similar appropriate use criteria for eBX and limiting this treatment to patients who either are older than 65 years, have serious medical issues, are currently taking anticoagulants, are immobile, or simply cannot handle further dermatologic surgeries.

The American Medical Association has developed new Category III CPT codes for treatment of the skin with eBX that will become effective January 2016.⁶ These codes take into consideration the need for a radiation oncologist and a physicist to be present for planning, dosimetry, simulation, and selection of parameters for the appropriate depth. Although I do not know the reimbursement rates for these new codes yet, they will likely be substantially less than the current payment for treatment with eBX. That said, the gravy train has left the station, and those who have invested in the devices for eBX will either see the benefit of continued treatment for their patients or divest themselves of eBX now that the reimbursement will be more modest.

Some of my dermatology colleagues, who also are some of my very good friends, have a visceral and absolute objection to the use of any form of radiation therapy, and I respect their opinions. However, eBX does play a role in treating cutaneous malignancies, and our radiation oncology colleagues—many who treat patients with extensive, aggressive, and recurrent skin cancers—also have a place at the table.

Speaking as a fellowship-trained dermatologic surgeon and a department chair, I am very aware that the teaching we provide today for our dermatology residents and fellows is likely to be their modus operandi for the future, a future in which the Patient Protection and Affordable Care Act will force physicians to carefully choose quality of care over personal gain and where financial rewards will be based on appropriate utilization and measurable outcomes. Electronic brachytherapy is one tool amongst many. I have a plethora of patients in their 70s and 80s who have given up on surgery for skin cancer and who would prefer painless treatment with eBX, which allows for the appropriate use of such a controversial therapy.

Acknowledgments—I would like to thank Janellen Smith, MD (Irvine, California), Joshua Spanogle, MD (Saint Augustine, Florida), and Jordan 
V. Wang, MBE (Philadelphia, Pennsylvania), for their constructive comments.

The introduction of high-density radiation electronic brachytherapy (eBX) for the treatment of nonmelanoma skin cancers has induced great angst within the dermatology community.¹ The Current Procedural Terminology (CPT) code 0182T (high dose rate eBX) reimburses at an extraordinarily high rate, which has drawn a substantial amount of attention. Some critics see it as another case of overutilization, of sucking more money out of a bleeding Medicare system. The financial opportunity afforded by eBX has even led some entrepreneurs to purchase dermatology clinics so that skin cancer patients can be treated via this modality instead of more traditional and less costly techniques (personal communication, 2014).

Among radiation oncologists, high-density radiation eBX is considered to be an important treatment option for select patients who have skin cancers staged as T1 or T2 tumors that are 4 cm or smaller in diameter and 5 mm or less in depth.² Additionally, ideal candidates for nonsurgical treatment options such as eBX include patients with lesions in cosmetically challenging areas (eg, ears, nose), those who may experience problematic wound healing due to tumor location (eg, lower extremities) or medical conditions (eg, diabetes mellitus, peripheral vascular disease), those with medical comorbidities that may preclude them from surgery, those currently taking anticoagulants, and those who are not interested in undergoing surgery.

A common criticism of eBX is that there is little data on long-term treatment outcomes, which will soon be addressed by a 5-year multicenter, prospective, randomized study of 720 patients with basal cell carcinoma and squamous cell carcinoma led by the University of California, Irvine, and the University of California, San Diego (study protocol currently with institutional review board). Another criticism is that some manufacturers of eBX devices gained the less rigorous US Food and Drug Administration Premarket Notification 510(k) certification; however, this certification is quite commonplace in the United States, and an examination of the data actually shows a lower recall rate with this method when compared to the longer premarket approval application process.³ A more important criticism of eBX might be that radiation therapy is associated with a substantial increase in skin cancers that may occur decades later in irradiated areas; however, there remains a paucity of studies examining the safety data on eBX during the posttreatment period when such effects would be expected.

In practice, the forces for good and evil are not only limited to those who utilize eBX. It is widely known that CPT codes for Mohs micrographic surgery also have been abused—that is, the procedure has been used in circumstances where it was not absolutely necessary⁴—which led to an effort by dermatologic surgery organizations to agree on appropriate use criteria for Mohs surgery.⁵ These criteria are not perfect but should help curb the misuse of a valuable technique, which is one that is recognized as being optimal for the treatment of complex skin cancers. One might suggest forming similar appropriate use criteria for eBX and limiting this treatment to patients who either are older than 65 years, have serious medical issues, are currently taking anticoagulants, are immobile, or simply cannot handle further dermatologic surgeries.

The American Medical Association has developed new Category III CPT codes for treatment of the skin with eBX that will become effective January 2016.⁶ These codes take into consideration the need for a radiation oncologist and a physicist to be present for planning, dosimetry, simulation, and selection of parameters for the appropriate depth. Although I do not know the reimbursement rates for these new codes yet, they will likely be substantially less than the current payment for treatment with eBX. That said, the gravy train has left the station, and those who have invested in the devices for eBX will either see the benefit of continued treatment for their patients or divest themselves of eBX now that the reimbursement will be more modest.

Some of my dermatology colleagues, who also are some of my very good friends, have a visceral and absolute objection to the use of any form of radiation therapy, and I respect their opinions. However, eBX does play a role in treating cutaneous malignancies, and our radiation oncology colleagues—many who treat patients with extensive, aggressive, and recurrent skin cancers—also have a place at the table.

Speaking as a fellowship-trained dermatologic surgeon and a department chair, I am very aware that the teaching we provide today for our dermatology residents and fellows is likely to be their modus operandi for the future, a future in which the Patient Protection and Affordable Care Act will force physicians to carefully choose quality of care over personal gain and where financial rewards will be based on appropriate utilization and measurable outcomes. Electronic brachytherapy is one tool amongst many. I have a plethora of patients in their 70s and 80s who have given up on surgery for skin cancer and who would prefer painless treatment with eBX, which allows for the appropriate use of such a controversial therapy.

Acknowledgments—I would like to thank Janellen Smith, MD (Irvine, California), Joshua Spanogle, MD (Saint Augustine, Florida), and Jordan 
V. Wang, MBE (Philadelphia, Pennsylvania), for their constructive comments.

The introduction of high-density radiation electronic brachytherapy (eBX) for the treatment of nonmelanoma skin cancers has induced great angst within the dermatology community.¹ The Current Procedural Terminology (CPT) code 0182T (high dose rate eBX) reimburses at an extraordinarily high rate, which has drawn a substantial amount of attention. Some critics see it as another case of overutilization, of sucking more money out of a bleeding Medicare system. The financial opportunity afforded by eBX has even led some entrepreneurs to purchase dermatology clinics so that skin cancer patients can be treated via this modality instead of more traditional and less costly techniques (personal communication, 2014).

Among radiation oncologists, high-density radiation eBX is considered to be an important treatment option for select patients who have skin cancers staged as T1 or T2 tumors that are 4 cm or smaller in diameter and 5 mm or less in depth.² Additionally, ideal candidates for nonsurgical treatment options such as eBX include patients with lesions in cosmetically challenging areas (eg, ears, nose), those who may experience problematic wound healing due to tumor location (eg, lower extremities) or medical conditions (eg, diabetes mellitus, peripheral vascular disease), those with medical comorbidities that may preclude them from surgery, those currently taking anticoagulants, and those who are not interested in undergoing surgery.

A common criticism of eBX is that there is little data on long-term treatment outcomes, which will soon be addressed by a 5-year multicenter, prospective, randomized study of 720 patients with basal cell carcinoma and squamous cell carcinoma led by the University of California, Irvine, and the University of California, San Diego (study protocol currently with institutional review board). Another criticism is that some manufacturers of eBX devices gained the less rigorous US Food and Drug Administration Premarket Notification 510(k) certification; however, this certification is quite commonplace in the United States, and an examination of the data actually shows a lower recall rate with this method when compared to the longer premarket approval application process.³ A more important criticism of eBX might be that radiation therapy is associated with a substantial increase in skin cancers that may occur decades later in irradiated areas; however, there remains a paucity of studies examining the safety data on eBX during the posttreatment period when such effects would be expected.

In practice, the forces for good and evil are not only limited to those who utilize eBX. It is widely known that CPT codes for Mohs micrographic surgery also have been abused—that is, the procedure has been used in circumstances where it was not absolutely necessary⁴—which led to an effort by dermatologic surgery organizations to agree on appropriate use criteria for Mohs surgery.⁵ These criteria are not perfect but should help curb the misuse of a valuable technique, which is one that is recognized as being optimal for the treatment of complex skin cancers. One might suggest forming similar appropriate use criteria for eBX and limiting this treatment to patients who either are older than 65 years, have serious medical issues, are currently taking anticoagulants, are immobile, or simply cannot handle further dermatologic surgeries.

The American Medical Association has developed new Category III CPT codes for treatment of the skin with eBX that will become effective January 2016.⁶ These codes take into consideration the need for a radiation oncologist and a physicist to be present for planning, dosimetry, simulation, and selection of parameters for the appropriate depth. Although I do not know the reimbursement rates for these new codes yet, they will likely be substantially less than the current payment for treatment with eBX. That said, the gravy train has left the station, and those who have invested in the devices for eBX will either see the benefit of continued treatment for their patients or divest themselves of eBX now that the reimbursement will be more modest.

Some of my dermatology colleagues, who also are some of my very good friends, have a visceral and absolute objection to the use of any form of radiation therapy, and I respect their opinions. However, eBX does play a role in treating cutaneous malignancies, and our radiation oncology colleagues—many who treat patients with extensive, aggressive, and recurrent skin cancers—also have a place at the table.

Speaking as a fellowship-trained dermatologic surgeon and a department chair, I am very aware that the teaching we provide today for our dermatology residents and fellows is likely to be their modus operandi for the future, a future in which the Patient Protection and Affordable Care Act will force physicians to carefully choose quality of care over personal gain and where financial rewards will be based on appropriate utilization and measurable outcomes. Electronic brachytherapy is one tool amongst many. I have a plethora of patients in their 70s and 80s who have given up on surgery for skin cancer and who would prefer painless treatment with eBX, which allows for the appropriate use of such a controversial therapy.

Acknowledgments—I would like to thank Janellen Smith, MD (Irvine, California), Joshua Spanogle, MD (Saint Augustine, Florida), and Jordan 
V. Wang, MBE (Philadelphia, Pennsylvania), for their constructive comments.

To the Editor:

A 62-year-old woman with an extensive history of cutaneous and oral lichen planus (OLP) presented with gradual worsening of oral pain refractory to previously successful treatment regimens. The pains were described as sharp sensations originating in the right superior oral cavity, occurring almost constantly over the course of 2 months. On examination, the oral mucosa on the right side showed lacy, white, hyperkeratotic buccal lesions, as well as superficial erythematous erosion on the right upper alveolar ridge mucosa (Figure 1). On the left side, lacy, white, reticular patches were noted along the buccal mucosa. Gingival desquamation with superficial erosions were observed bilaterally, extending to the upper alveolar ridge in some locations. The skin examination revealed resolving, nonirritated, violaceous, flat-topped papules with a white-gray hue on the upper back and vulva.

Figure 1. Erosive oral lichen planus of the right maxillary alveolar ridge.

The rest of the physical examination was benign, including a lack of appreciable lymphadenopathy, a cranial nerve examination without focal deficit, and the presence of fluent unaffected speech. On review of systems, the patient denied fevers, chills, weight loss, or night sweats. She had no history of skin cancer or oropharyngeal cancer. Family history revealed that her father had nonmelanoma skin cancer of the head and neck. She denied heavy alcohol use as well as history of smoking or other oral tobacco products. Laboratory tests revealed a complete blood cell count and comprehensive metabolic panel that was within reference range. Due to the refractory nature of the pain, which was out of character for OLP, the patient was referred to an oral maxillofacial surgeon who extracted right maxillary teeth adjacent to the erosion to obtain an adequate specimen for surgical biopsy of the lesion itself. Histopathology confirmed the diagnosis of chronic erosive OLP with malignant transformation to localized squamous cell carcinoma (SCC) of the right maxilla.

While awaiting treatment, she began to develop unremitting headaches and painful shooting sensations beginning in the right superior oral mucosa, radiating to the ipsilateral naris, nasolabial folds, malar cheek, and temple region. This clinical picture was consistent with neuralgia occurring along the maxillary nerve. A subsequent computed tomography scan revealed local bony destruction of the primary tumor and likely perineural involvement (Figure 2), without notable nodal involvement or metastasis (stage III: T4aN0M0). An otolaryngologist performed a wide alveolar and maxillary excision with lymph node dissection. Surgical margins were deemed as negative and there was no evidence of nodal disease. She was later seen by the oncology and radiation oncology teams and received several courses of chemoradiotherapy.

Figure 2. Coronal (A) and axial (B) computed tomography demonstrated right maxillary bony destruction.

Seven months later, a new indurated ulcer was noted on the left lateral tongue. Biopsy revealed a new primary oral SCC (OSCC), which also was excised by an otolaryngologist. Recent computed tomography did not detect any recurrence or potential metastases, but the patient subsequently was lost to follow-up.

Lichen planus is an idiopathic inflammatory disease most commonly affecting the cutaneous skin as well as the oral mucosa, genital mucosa, nails, and scalp. Oral lichen planus is a relatively common manifestation, found in approximately 1% to 2% of individuals older than 15 years.¹ Epidemiologic studies revealed that OLP is uncommon in children,^2,3 it affects women more frequently than men (approximately 3:1 ratio),³ and its incidence peaks between 30 and 60 years of age.⁴ The literature on malignant transformation of OLP is varied and controversial, with some early investigations such as Krutchkoff et al⁵ concluding that the reported cases often fall short of supporting OLP as a premalignant source of OSCC due to insufficient evidence in claimed case reports supporting the diagnosis of OLP histopathologically, the occurrence of OSCC in sites where OLP lesions did not previously exist, and uncertainty regarding confounding factors such as carcinogen exposure.⁵ In contrast, a longitudinal cohort study reported malignant transformation in 2.4% of 
OLP cases (N=327), with a standardized incidence ratio of 17.7 (95% confidence interval, 8.8-35.3) when compared to a control group.⁶ Current literature has predominantly sided with the notion that OLP, especially the erosive variant, carries the risk for malignant potential⁶ as well as the World Health Organization’s classification of the disorder as precancerous.³

The pathophysiology of OLP and its potential for malignant transformation are unknown. It is believed that cell-mediated immunity, specifically CD8⁺ lymphocytes targeting stratum basale keratinocytes for apoptosis via the caspase cascade, plays a major role in the development of OLP, beginning with Langerhans cell recognition of an unknown basal cell antigen.³ Moreover, it is postulated that antigen expression is induced by certain drugs, infections, and contact allergens such as dental amalgams, explaining their known associations with OLP initiation and exacerbation. The etiology behind OLP developing into OSCC also is poorly understood and many different hypotheses have been suggested. Modified expression of p53, a 53-kd protein, in OLP patients has been demonstrated.⁶ Some investigators propose that a lack of the expected keratinocyte apoptotic response to the cell-mediated attack may be etiologic in cancerous transformation.³ Given their utility in treatment of OLP, there also has been apprehension over the potential for immunosuppressant medications leading to decreased expression of antitumor regulators and development of malignant cells, though it has not been substantiated by current literature.⁶ Finally, some cases of OSCC are believed to have been linked to N-nitrosobenzylmethylamine, a known carcinogen produced by colonized Candida albicans, which also may play a role in OLP treated with immunosuppressants.⁷

Clinically, OLP lesions are known to be more chronic in nature than cutaneous lichen planus.⁷ There are 6 classifications of OLP: reticular (lacy white with Wickham striae), plaquelike, papular, atrophic, bullous, and erosive. The latter 3 are known to be the more symptomatic manifestations.^3,7 Of note, the atrophic and erosive forms are believed to account for the vast majority of cases of malignant transformation of OLP to OSCC. Approximately 90% of patients have involvement of multiple oral sites, with the most common affected areas being the buccal mucosa (90%), gingival margin (56%), and dorsal tongue (34%).⁷ Symptoms include increased sensitivity to foods, intense local pain, and coarse-feeling mucosa. The nature of the disease favors an active-quiescent-active course, with flares occurring after direct irritation (ie, dental procedures, Köbner phenomenon), emotional stress, medication use, and systemic illness.⁷ The differential diagnosis of OLP includes bite trauma, candidiasis, pemphigus, leukoplakia, lichenoid drug reaction, pemphigoid, and graft-versus-host disease.⁴ Red flags of malignant transformation include induration, worsening ulceration in the setting of previously effective therapy, and presence of constitutional symptoms.

Regarding the behavior of OSCC after malignant transformation, the literature seems to suggest a tendency for well-differentiated noninvasive tumors that most often occur on the buccal mucosa (43%), tongue (33%), gingiva (19%), and palate (4.8%).⁸ Interestingly, one study described that only 1 (4.8%) of 21 patients with OLP and OSCC was deemed as having stage II or higher disease at time of diagnosis. Likewise, 90% of the biopsied samples revealed well-differentiated carcinomas.⁸ These findings clearly contrast with our case in which the patient experienced rapid conversion of localized OSCC to more invasive disease. Also of consequence in this study was the finding that a relatively high proportion of patients (29% [6/21]) developed at least one other primary OSCC lesion over the course of follow-up.⁸ This finding is consistent with our patient.

Last, management of OLP lesions is most commonly accomplished with topical steroids such as fluocinolone acetonide or triamcinolone acetonide.³ Treatment of gingival disease may be enhanced with the use of form-fitting trays.² For refractory erosive disease, tacrolimus ointment has been demonstrated as a useful backup therapy but may actually be associated with the development of OSCC through alteration of MAPK and p53.³ Some investigators suggest regular 4-month 
follow-up of OLP patients to detect if acute worsening and or refractoriness to treatment have signified early dysplastic change. Various scoring systems also have been suggested for following up on the severity of OLP lesions.³

The management of OSCC usually is accomplished via surgery, radiation, or both. The decision is dependent on tumor stage and the patient’s individual limitations. It is highly recommended that patients with OSCC arising from OLP be closely followed after diagnosis of cancer, with some sources suggesting follow-up every 2 months for the first 6 to 9 months after diagnosis due to the relatively high rate of discovery of nodal metastases and new primary lesions in that critical time span.⁸ Thereafter, an examination every 4 months is suggested as sufficient for detecting future complications.

To the Editor:

A 62-year-old woman with an extensive history of cutaneous and oral lichen planus (OLP) presented with gradual worsening of oral pain refractory to previously successful treatment regimens. The pains were described as sharp sensations originating in the right superior oral cavity, occurring almost constantly over the course of 2 months. On examination, the oral mucosa on the right side showed lacy, white, hyperkeratotic buccal lesions, as well as superficial erythematous erosion on the right upper alveolar ridge mucosa (Figure 1). On the left side, lacy, white, reticular patches were noted along the buccal mucosa. Gingival desquamation with superficial erosions were observed bilaterally, extending to the upper alveolar ridge in some locations. The skin examination revealed resolving, nonirritated, violaceous, flat-topped papules with a white-gray hue on the upper back and vulva.

Figure 1. Erosive oral lichen planus of the right maxillary alveolar ridge.

The rest of the physical examination was benign, including a lack of appreciable lymphadenopathy, a cranial nerve examination without focal deficit, and the presence of fluent unaffected speech. On review of systems, the patient denied fevers, chills, weight loss, or night sweats. She had no history of skin cancer or oropharyngeal cancer. Family history revealed that her father had nonmelanoma skin cancer of the head and neck. She denied heavy alcohol use as well as history of smoking or other oral tobacco products. Laboratory tests revealed a complete blood cell count and comprehensive metabolic panel that was within reference range. Due to the refractory nature of the pain, which was out of character for OLP, the patient was referred to an oral maxillofacial surgeon who extracted right maxillary teeth adjacent to the erosion to obtain an adequate specimen for surgical biopsy of the lesion itself. Histopathology confirmed the diagnosis of chronic erosive OLP with malignant transformation to localized squamous cell carcinoma (SCC) of the right maxilla.

While awaiting treatment, she began to develop unremitting headaches and painful shooting sensations beginning in the right superior oral mucosa, radiating to the ipsilateral naris, nasolabial folds, malar cheek, and temple region. This clinical picture was consistent with neuralgia occurring along the maxillary nerve. A subsequent computed tomography scan revealed local bony destruction of the primary tumor and likely perineural involvement (Figure 2), without notable nodal involvement or metastasis (stage III: T4aN0M0). An otolaryngologist performed a wide alveolar and maxillary excision with lymph node dissection. Surgical margins were deemed as negative and there was no evidence of nodal disease. She was later seen by the oncology and radiation oncology teams and received several courses of chemoradiotherapy.

Figure 2. Coronal (A) and axial (B) computed tomography demonstrated right maxillary bony destruction.

Seven months later, a new indurated ulcer was noted on the left lateral tongue. Biopsy revealed a new primary oral SCC (OSCC), which also was excised by an otolaryngologist. Recent computed tomography did not detect any recurrence or potential metastases, but the patient subsequently was lost to follow-up.

Lichen planus is an idiopathic inflammatory disease most commonly affecting the cutaneous skin as well as the oral mucosa, genital mucosa, nails, and scalp. Oral lichen planus is a relatively common manifestation, found in approximately 1% to 2% of individuals older than 15 years.¹ Epidemiologic studies revealed that OLP is uncommon in children,^2,3 it affects women more frequently than men (approximately 3:1 ratio),³ and its incidence peaks between 30 and 60 years of age.⁴ The literature on malignant transformation of OLP is varied and controversial, with some early investigations such as Krutchkoff et al⁵ concluding that the reported cases often fall short of supporting OLP as a premalignant source of OSCC due to insufficient evidence in claimed case reports supporting the diagnosis of OLP histopathologically, the occurrence of OSCC in sites where OLP lesions did not previously exist, and uncertainty regarding confounding factors such as carcinogen exposure.⁵ In contrast, a longitudinal cohort study reported malignant transformation in 2.4% of 
OLP cases (N=327), with a standardized incidence ratio of 17.7 (95% confidence interval, 8.8-35.3) when compared to a control group.⁶ Current literature has predominantly sided with the notion that OLP, especially the erosive variant, carries the risk for malignant potential⁶ as well as the World Health Organization’s classification of the disorder as precancerous.³

The pathophysiology of OLP and its potential for malignant transformation are unknown. It is believed that cell-mediated immunity, specifically CD8⁺ lymphocytes targeting stratum basale keratinocytes for apoptosis via the caspase cascade, plays a major role in the development of OLP, beginning with Langerhans cell recognition of an unknown basal cell antigen.³ Moreover, it is postulated that antigen expression is induced by certain drugs, infections, and contact allergens such as dental amalgams, explaining their known associations with OLP initiation and exacerbation. The etiology behind OLP developing into OSCC also is poorly understood and many different hypotheses have been suggested. Modified expression of p53, a 53-kd protein, in OLP patients has been demonstrated.⁶ Some investigators propose that a lack of the expected keratinocyte apoptotic response to the cell-mediated attack may be etiologic in cancerous transformation.³ Given their utility in treatment of OLP, there also has been apprehension over the potential for immunosuppressant medications leading to decreased expression of antitumor regulators and development of malignant cells, though it has not been substantiated by current literature.⁶ Finally, some cases of OSCC are believed to have been linked to N-nitrosobenzylmethylamine, a known carcinogen produced by colonized Candida albicans, which also may play a role in OLP treated with immunosuppressants.⁷

Clinically, OLP lesions are known to be more chronic in nature than cutaneous lichen planus.⁷ There are 6 classifications of OLP: reticular (lacy white with Wickham striae), plaquelike, papular, atrophic, bullous, and erosive. The latter 3 are known to be the more symptomatic manifestations.^3,7 Of note, the atrophic and erosive forms are believed to account for the vast majority of cases of malignant transformation of OLP to OSCC. Approximately 90% of patients have involvement of multiple oral sites, with the most common affected areas being the buccal mucosa (90%), gingival margin (56%), and dorsal tongue (34%).⁷ Symptoms include increased sensitivity to foods, intense local pain, and coarse-feeling mucosa. The nature of the disease favors an active-quiescent-active course, with flares occurring after direct irritation (ie, dental procedures, Köbner phenomenon), emotional stress, medication use, and systemic illness.⁷ The differential diagnosis of OLP includes bite trauma, candidiasis, pemphigus, leukoplakia, lichenoid drug reaction, pemphigoid, and graft-versus-host disease.⁴ Red flags of malignant transformation include induration, worsening ulceration in the setting of previously effective therapy, and presence of constitutional symptoms.

Regarding the behavior of OSCC after malignant transformation, the literature seems to suggest a tendency for well-differentiated noninvasive tumors that most often occur on the buccal mucosa (43%), tongue (33%), gingiva (19%), and palate (4.8%).⁸ Interestingly, one study described that only 1 (4.8%) of 21 patients with OLP and OSCC was deemed as having stage II or higher disease at time of diagnosis. Likewise, 90% of the biopsied samples revealed well-differentiated carcinomas.⁸ These findings clearly contrast with our case in which the patient experienced rapid conversion of localized OSCC to more invasive disease. Also of consequence in this study was the finding that a relatively high proportion of patients (29% [6/21]) developed at least one other primary OSCC lesion over the course of follow-up.⁸ This finding is consistent with our patient.

Last, management of OLP lesions is most commonly accomplished with topical steroids such as fluocinolone acetonide or triamcinolone acetonide.³ Treatment of gingival disease may be enhanced with the use of form-fitting trays.² For refractory erosive disease, tacrolimus ointment has been demonstrated as a useful backup therapy but may actually be associated with the development of OSCC through alteration of MAPK and p53.³ Some investigators suggest regular 4-month 
follow-up of OLP patients to detect if acute worsening and or refractoriness to treatment have signified early dysplastic change. Various scoring systems also have been suggested for following up on the severity of OLP lesions.³

The management of OSCC usually is accomplished via surgery, radiation, or both. The decision is dependent on tumor stage and the patient’s individual limitations. It is highly recommended that patients with OSCC arising from OLP be closely followed after diagnosis of cancer, with some sources suggesting follow-up every 2 months for the first 6 to 9 months after diagnosis due to the relatively high rate of discovery of nodal metastases and new primary lesions in that critical time span.⁸ Thereafter, an examination every 4 months is suggested as sufficient for detecting future complications.

To the Editor:

A 62-year-old woman with an extensive history of cutaneous and oral lichen planus (OLP) presented with gradual worsening of oral pain refractory to previously successful treatment regimens. The pains were described as sharp sensations originating in the right superior oral cavity, occurring almost constantly over the course of 2 months. On examination, the oral mucosa on the right side showed lacy, white, hyperkeratotic buccal lesions, as well as superficial erythematous erosion on the right upper alveolar ridge mucosa (Figure 1). On the left side, lacy, white, reticular patches were noted along the buccal mucosa. Gingival desquamation with superficial erosions were observed bilaterally, extending to the upper alveolar ridge in some locations. The skin examination revealed resolving, nonirritated, violaceous, flat-topped papules with a white-gray hue on the upper back and vulva.

Figure 1. Erosive oral lichen planus of the right maxillary alveolar ridge.

The rest of the physical examination was benign, including a lack of appreciable lymphadenopathy, a cranial nerve examination without focal deficit, and the presence of fluent unaffected speech. On review of systems, the patient denied fevers, chills, weight loss, or night sweats. She had no history of skin cancer or oropharyngeal cancer. Family history revealed that her father had nonmelanoma skin cancer of the head and neck. She denied heavy alcohol use as well as history of smoking or other oral tobacco products. Laboratory tests revealed a complete blood cell count and comprehensive metabolic panel that was within reference range. Due to the refractory nature of the pain, which was out of character for OLP, the patient was referred to an oral maxillofacial surgeon who extracted right maxillary teeth adjacent to the erosion to obtain an adequate specimen for surgical biopsy of the lesion itself. Histopathology confirmed the diagnosis of chronic erosive OLP with malignant transformation to localized squamous cell carcinoma (SCC) of the right maxilla.

While awaiting treatment, she began to develop unremitting headaches and painful shooting sensations beginning in the right superior oral mucosa, radiating to the ipsilateral naris, nasolabial folds, malar cheek, and temple region. This clinical picture was consistent with neuralgia occurring along the maxillary nerve. A subsequent computed tomography scan revealed local bony destruction of the primary tumor and likely perineural involvement (Figure 2), without notable nodal involvement or metastasis (stage III: T4aN0M0). An otolaryngologist performed a wide alveolar and maxillary excision with lymph node dissection. Surgical margins were deemed as negative and there was no evidence of nodal disease. She was later seen by the oncology and radiation oncology teams and received several courses of chemoradiotherapy.

Figure 2. Coronal (A) and axial (B) computed tomography demonstrated right maxillary bony destruction.

Seven months later, a new indurated ulcer was noted on the left lateral tongue. Biopsy revealed a new primary oral SCC (OSCC), which also was excised by an otolaryngologist. Recent computed tomography did not detect any recurrence or potential metastases, but the patient subsequently was lost to follow-up.

Lichen planus is an idiopathic inflammatory disease most commonly affecting the cutaneous skin as well as the oral mucosa, genital mucosa, nails, and scalp. Oral lichen planus is a relatively common manifestation, found in approximately 1% to 2% of individuals older than 15 years.¹ Epidemiologic studies revealed that OLP is uncommon in children,^2,3 it affects women more frequently than men (approximately 3:1 ratio),³ and its incidence peaks between 30 and 60 years of age.⁴ The literature on malignant transformation of OLP is varied and controversial, with some early investigations such as Krutchkoff et al⁵ concluding that the reported cases often fall short of supporting OLP as a premalignant source of OSCC due to insufficient evidence in claimed case reports supporting the diagnosis of OLP histopathologically, the occurrence of OSCC in sites where OLP lesions did not previously exist, and uncertainty regarding confounding factors such as carcinogen exposure.⁵ In contrast, a longitudinal cohort study reported malignant transformation in 2.4% of 
OLP cases (N=327), with a standardized incidence ratio of 17.7 (95% confidence interval, 8.8-35.3) when compared to a control group.⁶ Current literature has predominantly sided with the notion that OLP, especially the erosive variant, carries the risk for malignant potential⁶ as well as the World Health Organization’s classification of the disorder as precancerous.³

The pathophysiology of OLP and its potential for malignant transformation are unknown. It is believed that cell-mediated immunity, specifically CD8⁺ lymphocytes targeting stratum basale keratinocytes for apoptosis via the caspase cascade, plays a major role in the development of OLP, beginning with Langerhans cell recognition of an unknown basal cell antigen.³ Moreover, it is postulated that antigen expression is induced by certain drugs, infections, and contact allergens such as dental amalgams, explaining their known associations with OLP initiation and exacerbation. The etiology behind OLP developing into OSCC also is poorly understood and many different hypotheses have been suggested. Modified expression of p53, a 53-kd protein, in OLP patients has been demonstrated.⁶ Some investigators propose that a lack of the expected keratinocyte apoptotic response to the cell-mediated attack may be etiologic in cancerous transformation.³ Given their utility in treatment of OLP, there also has been apprehension over the potential for immunosuppressant medications leading to decreased expression of antitumor regulators and development of malignant cells, though it has not been substantiated by current literature.⁶ Finally, some cases of OSCC are believed to have been linked to N-nitrosobenzylmethylamine, a known carcinogen produced by colonized Candida albicans, which also may play a role in OLP treated with immunosuppressants.⁷

Clinically, OLP lesions are known to be more chronic in nature than cutaneous lichen planus.⁷ There are 6 classifications of OLP: reticular (lacy white with Wickham striae), plaquelike, papular, atrophic, bullous, and erosive. The latter 3 are known to be the more symptomatic manifestations.^3,7 Of note, the atrophic and erosive forms are believed to account for the vast majority of cases of malignant transformation of OLP to OSCC. Approximately 90% of patients have involvement of multiple oral sites, with the most common affected areas being the buccal mucosa (90%), gingival margin (56%), and dorsal tongue (34%).⁷ Symptoms include increased sensitivity to foods, intense local pain, and coarse-feeling mucosa. The nature of the disease favors an active-quiescent-active course, with flares occurring after direct irritation (ie, dental procedures, Köbner phenomenon), emotional stress, medication use, and systemic illness.⁷ The differential diagnosis of OLP includes bite trauma, candidiasis, pemphigus, leukoplakia, lichenoid drug reaction, pemphigoid, and graft-versus-host disease.⁴ Red flags of malignant transformation include induration, worsening ulceration in the setting of previously effective therapy, and presence of constitutional symptoms.

Regarding the behavior of OSCC after malignant transformation, the literature seems to suggest a tendency for well-differentiated noninvasive tumors that most often occur on the buccal mucosa (43%), tongue (33%), gingiva (19%), and palate (4.8%).⁸ Interestingly, one study described that only 1 (4.8%) of 21 patients with OLP and OSCC was deemed as having stage II or higher disease at time of diagnosis. Likewise, 90% of the biopsied samples revealed well-differentiated carcinomas.⁸ These findings clearly contrast with our case in which the patient experienced rapid conversion of localized OSCC to more invasive disease. Also of consequence in this study was the finding that a relatively high proportion of patients (29% [6/21]) developed at least one other primary OSCC lesion over the course of follow-up.⁸ This finding is consistent with our patient.

Last, management of OLP lesions is most commonly accomplished with topical steroids such as fluocinolone acetonide or triamcinolone acetonide.³ Treatment of gingival disease may be enhanced with the use of form-fitting trays.² For refractory erosive disease, tacrolimus ointment has been demonstrated as a useful backup therapy but may actually be associated with the development of OSCC through alteration of MAPK and p53.³ Some investigators suggest regular 4-month 
follow-up of OLP patients to detect if acute worsening and or refractoriness to treatment have signified early dysplastic change. Various scoring systems also have been suggested for following up on the severity of OLP lesions.³

The management of OSCC usually is accomplished via surgery, radiation, or both. The decision is dependent on tumor stage and the patient’s individual limitations. It is highly recommended that patients with OSCC arising from OLP be closely followed after diagnosis of cancer, with some sources suggesting follow-up every 2 months for the first 6 to 9 months after diagnosis due to the relatively high rate of discovery of nodal metastases and new primary lesions in that critical time span.⁸ Thereafter, an examination every 4 months is suggested as sufficient for detecting future complications.

Cryosurgery followed by topical ingenol mebutate cleared extensive regions of actinic keratosis, which helped reveal residual squamous cell carcinomas, according to a report in the August issue of the Journal of Drugs in Dermatology.

The findings show that ingenol mebutate can clear multiple AKs and reduce the number of scarring biopsies required to identify SCCs, said Dr. Miriam S. Bettencourt, a dermatologist in group practice in Henderson, Nev. “In our dermatology clinic, many of the patients with a long history of AK who were treated with ingenol mebutate used sequentially after cryosurgery have achieved complete or partial clearance of AKs.”

Ingenol mebutate gel after cryosurgery cleared AKs more effectively than cryosurgery alone in a recent phase III trial (J Drugs Dermatol. 2014 Jun;13[6]741-7), Dr. Bettencourt noted. She described six men and one woman who each had at least 10 recurrent or hyperkeratotic AKs and previously had undergone cryosurgery. She treated all patients with cryosurgery, followed 2 weeks later by two or three once-daily applications of ingenol mebutate gel at strengths of 0.05% or 0.015%, respectively (J Drugs Dermatol. 2015 Aug;14[8];813-8). One course of ingenol mebutate gel cleared 50%-100% of AKs, Dr. Bettencourt said. She treated residual AKs with cryosurgery, and five patients also received at least one more course of ingenol mebutate to re-treat a partially cleared area or to treat a separate area. Shave biopsies of 10 residual suspicious lesions taken 3-8 months later all revealed invasive SCCs, which were treated with Mohs micrographic surgery (MMS). “These lesions may have been preexisting at the time of topical treatment but not readily recognized as suspicious in the heavily actinically damaged skin, in which suspected or small SCCs may be adjacent to or obscured by AKs,” she said. “Alternatively, these tumors may have been spontaneous new SCCs. In either case, we suggest that effective clearance of AKs from the palette of sun-damaged skin with ingenol mebutate permitted prompt recognition of these lesions as suspicious, and led to further diagnosis and treatment with MMS.”

All patients developed mild to moderate localized redness, flaking, and crusting starting on the second day of ingenol mebutate treatment and resolving within a week of finishing the course, Dr. Bettencourt said.

She reported that she had no relevant financial conflicts.

Cryosurgery followed by topical ingenol mebutate cleared extensive regions of actinic keratosis, which helped reveal residual squamous cell carcinomas, according to a report in the August issue of the Journal of Drugs in Dermatology.

The findings show that ingenol mebutate can clear multiple AKs and reduce the number of scarring biopsies required to identify SCCs, said Dr. Miriam S. Bettencourt, a dermatologist in group practice in Henderson, Nev. “In our dermatology clinic, many of the patients with a long history of AK who were treated with ingenol mebutate used sequentially after cryosurgery have achieved complete or partial clearance of AKs.”

Ingenol mebutate gel after cryosurgery cleared AKs more effectively than cryosurgery alone in a recent phase III trial (J Drugs Dermatol. 2014 Jun;13[6]741-7), Dr. Bettencourt noted. She described six men and one woman who each had at least 10 recurrent or hyperkeratotic AKs and previously had undergone cryosurgery. She treated all patients with cryosurgery, followed 2 weeks later by two or three once-daily applications of ingenol mebutate gel at strengths of 0.05% or 0.015%, respectively (J Drugs Dermatol. 2015 Aug;14[8];813-8). One course of ingenol mebutate gel cleared 50%-100% of AKs, Dr. Bettencourt said. She treated residual AKs with cryosurgery, and five patients also received at least one more course of ingenol mebutate to re-treat a partially cleared area or to treat a separate area. Shave biopsies of 10 residual suspicious lesions taken 3-8 months later all revealed invasive SCCs, which were treated with Mohs micrographic surgery (MMS). “These lesions may have been preexisting at the time of topical treatment but not readily recognized as suspicious in the heavily actinically damaged skin, in which suspected or small SCCs may be adjacent to or obscured by AKs,” she said. “Alternatively, these tumors may have been spontaneous new SCCs. In either case, we suggest that effective clearance of AKs from the palette of sun-damaged skin with ingenol mebutate permitted prompt recognition of these lesions as suspicious, and led to further diagnosis and treatment with MMS.”

All patients developed mild to moderate localized redness, flaking, and crusting starting on the second day of ingenol mebutate treatment and resolving within a week of finishing the course, Dr. Bettencourt said.

She reported that she had no relevant financial conflicts.

Cryosurgery followed by topical ingenol mebutate cleared extensive regions of actinic keratosis, which helped reveal residual squamous cell carcinomas, according to a report in the August issue of the Journal of Drugs in Dermatology.

The findings show that ingenol mebutate can clear multiple AKs and reduce the number of scarring biopsies required to identify SCCs, said Dr. Miriam S. Bettencourt, a dermatologist in group practice in Henderson, Nev. “In our dermatology clinic, many of the patients with a long history of AK who were treated with ingenol mebutate used sequentially after cryosurgery have achieved complete or partial clearance of AKs.”

Ingenol mebutate gel after cryosurgery cleared AKs more effectively than cryosurgery alone in a recent phase III trial (J Drugs Dermatol. 2014 Jun;13[6]741-7), Dr. Bettencourt noted. She described six men and one woman who each had at least 10 recurrent or hyperkeratotic AKs and previously had undergone cryosurgery. She treated all patients with cryosurgery, followed 2 weeks later by two or three once-daily applications of ingenol mebutate gel at strengths of 0.05% or 0.015%, respectively (J Drugs Dermatol. 2015 Aug;14[8];813-8). One course of ingenol mebutate gel cleared 50%-100% of AKs, Dr. Bettencourt said. She treated residual AKs with cryosurgery, and five patients also received at least one more course of ingenol mebutate to re-treat a partially cleared area or to treat a separate area. Shave biopsies of 10 residual suspicious lesions taken 3-8 months later all revealed invasive SCCs, which were treated with Mohs micrographic surgery (MMS). “These lesions may have been preexisting at the time of topical treatment but not readily recognized as suspicious in the heavily actinically damaged skin, in which suspected or small SCCs may be adjacent to or obscured by AKs,” she said. “Alternatively, these tumors may have been spontaneous new SCCs. In either case, we suggest that effective clearance of AKs from the palette of sun-damaged skin with ingenol mebutate permitted prompt recognition of these lesions as suspicious, and led to further diagnosis and treatment with MMS.”

All patients developed mild to moderate localized redness, flaking, and crusting starting on the second day of ingenol mebutate treatment and resolving within a week of finishing the course, Dr. Bettencourt said.

She reported that she had no relevant financial conflicts.

The Surgeon General has called on partners in prevention from various sectors to address skin cancer as a major public health problem. One of the main goals outlined in The Surgeon General’s Call to Action to Prevent Skin Cancer is to reduce harm from indoor tanning, which has been linked to increased risk for skin cancer, including melanoma, basal cell carcinoma, and squamous cell carcinoma.

Based on reports from the American Cancer Society, Centers for Disease Control and Prevention, Federal Trade Commission, Mayo Clinic, and US Food and Drug Administration, the following common myths about indoor tanning should be communicated to dermatology patients.

Myth: Indoor tanning will not increase your risk for skin cancer.

Fact: As many as 90% of melanomas are caused by UV exposure. Indoor tanning exposure to UVA and UVB radiation damages the skin and may lead to cancer. Melanoma is linked to severe sunburns, especially at a young age.

Myth: Indoor tanning is safer than tanning outdoors because it is a controlled dose of UV radiation.

Fact: Both indoor tanning and tanning outside are dangerous. Tanning beds may be more dangerous than the sun because they can be used at the same high intensity every day of the year, regardless of time of day, season, or cloud cover. Furthermore, the Surgeon General and US Food and Drug Administration report that an estimated 3000 Americans each year go to emergency departments with injuries caused by indoor tanning, including burns, eye injuries, immune suppression, and allergic reactions. Indoor tanning also causes premature skin aging.

Myth: A “base tan” protects your skin from sunburn.

Fact: Although many patients believe that a few sessions of indoor tanning will prevent them from burning in the sun, a tan does little to protect the skin from future UV exposure. In fact, the Centers for Disease Control and Prevention notes that people who tan indoors are more likely to report getting sunburned. The best way to protect the skin from sunburn is by using sun protection and avoiding indoor tanning.

Myth: Indoor tanning is a safe way to increase vitamin D levels.

Fact: It is important to get enough vitamin D; however, the safest way is through what you eat. Although UVB radiation helps the body produce vitamin D, patients do not need a tan to get that benefit. Ten to 15 minutes of unprotected natural sun exposure on the face and hands 2 to 3 times a week during the summer allows for a healthy dose of vitamin D. Dietary sources, such as low-fat milk, salmon, tuna, and fortified orange juice, are the safest way to get enough vitamin D.

Myth: Indoor tanning is approved by the government.

Fact: According to the Federal Trade Commission, no US government agency recommends the use of indoor tanning equipment. Tanning bed use by minors has been banned in many states, and efforts are ongoing to protect consumers younger than 18 years on local, state, and federal levels. In July 2009, the International Agency for Research on Cancer, part of the World Health Organization, moved tanning devices that emit UV radiation into the highest cancer risk category—carcinogenic to humans—concluding that they are more dangerous than previously thought.

Studies have consistently shown that indoor tanning increases a person’s risk of getting skin cancer and indoor tanning at a young age appears to be more strongly related to lifetime skin cancer risk. Patients should be reminded that every time they tan, they increase their risk of melanoma as well as premature skin aging and other skin cancers. Dermatologists should counsel patients on using sun protection and avoiding indoor tanning.

The Surgeon General has called on partners in prevention from various sectors to address skin cancer as a major public health problem. One of the main goals outlined in The Surgeon General’s Call to Action to Prevent Skin Cancer is to reduce harm from indoor tanning, which has been linked to increased risk for skin cancer, including melanoma, basal cell carcinoma, and squamous cell carcinoma.

Based on reports from the American Cancer Society, Centers for Disease Control and Prevention, Federal Trade Commission, Mayo Clinic, and US Food and Drug Administration, the following common myths about indoor tanning should be communicated to dermatology patients.

Myth: Indoor tanning will not increase your risk for skin cancer.

Fact: As many as 90% of melanomas are caused by UV exposure. Indoor tanning exposure to UVA and UVB radiation damages the skin and may lead to cancer. Melanoma is linked to severe sunburns, especially at a young age.

Myth: Indoor tanning is safer than tanning outdoors because it is a controlled dose of UV radiation.

Fact: Both indoor tanning and tanning outside are dangerous. Tanning beds may be more dangerous than the sun because they can be used at the same high intensity every day of the year, regardless of time of day, season, or cloud cover. Furthermore, the Surgeon General and US Food and Drug Administration report that an estimated 3000 Americans each year go to emergency departments with injuries caused by indoor tanning, including burns, eye injuries, immune suppression, and allergic reactions. Indoor tanning also causes premature skin aging.

Myth: A “base tan” protects your skin from sunburn.

Fact: Although many patients believe that a few sessions of indoor tanning will prevent them from burning in the sun, a tan does little to protect the skin from future UV exposure. In fact, the Centers for Disease Control and Prevention notes that people who tan indoors are more likely to report getting sunburned. The best way to protect the skin from sunburn is by using sun protection and avoiding indoor tanning.

Myth: Indoor tanning is a safe way to increase vitamin D levels.

Fact: It is important to get enough vitamin D; however, the safest way is through what you eat. Although UVB radiation helps the body produce vitamin D, patients do not need a tan to get that benefit. Ten to 15 minutes of unprotected natural sun exposure on the face and hands 2 to 3 times a week during the summer allows for a healthy dose of vitamin D. Dietary sources, such as low-fat milk, salmon, tuna, and fortified orange juice, are the safest way to get enough vitamin D.

Myth: Indoor tanning is approved by the government.

Fact: According to the Federal Trade Commission, no US government agency recommends the use of indoor tanning equipment. Tanning bed use by minors has been banned in many states, and efforts are ongoing to protect consumers younger than 18 years on local, state, and federal levels. In July 2009, the International Agency for Research on Cancer, part of the World Health Organization, moved tanning devices that emit UV radiation into the highest cancer risk category—carcinogenic to humans—concluding that they are more dangerous than previously thought.

Studies have consistently shown that indoor tanning increases a person’s risk of getting skin cancer and indoor tanning at a young age appears to be more strongly related to lifetime skin cancer risk. Patients should be reminded that every time they tan, they increase their risk of melanoma as well as premature skin aging and other skin cancers. Dermatologists should counsel patients on using sun protection and avoiding indoor tanning.

The Surgeon General has called on partners in prevention from various sectors to address skin cancer as a major public health problem. One of the main goals outlined in The Surgeon General’s Call to Action to Prevent Skin Cancer is to reduce harm from indoor tanning, which has been linked to increased risk for skin cancer, including melanoma, basal cell carcinoma, and squamous cell carcinoma.

Based on reports from the American Cancer Society, Centers for Disease Control and Prevention, Federal Trade Commission, Mayo Clinic, and US Food and Drug Administration, the following common myths about indoor tanning should be communicated to dermatology patients.

Myth: Indoor tanning will not increase your risk for skin cancer.

Fact: As many as 90% of melanomas are caused by UV exposure. Indoor tanning exposure to UVA and UVB radiation damages the skin and may lead to cancer. Melanoma is linked to severe sunburns, especially at a young age.

Myth: Indoor tanning is safer than tanning outdoors because it is a controlled dose of UV radiation.

Fact: Both indoor tanning and tanning outside are dangerous. Tanning beds may be more dangerous than the sun because they can be used at the same high intensity every day of the year, regardless of time of day, season, or cloud cover. Furthermore, the Surgeon General and US Food and Drug Administration report that an estimated 3000 Americans each year go to emergency departments with injuries caused by indoor tanning, including burns, eye injuries, immune suppression, and allergic reactions. Indoor tanning also causes premature skin aging.

Myth: A “base tan” protects your skin from sunburn.

Fact: Although many patients believe that a few sessions of indoor tanning will prevent them from burning in the sun, a tan does little to protect the skin from future UV exposure. In fact, the Centers for Disease Control and Prevention notes that people who tan indoors are more likely to report getting sunburned. The best way to protect the skin from sunburn is by using sun protection and avoiding indoor tanning.

Myth: Indoor tanning is a safe way to increase vitamin D levels.

Fact: It is important to get enough vitamin D; however, the safest way is through what you eat. Although UVB radiation helps the body produce vitamin D, patients do not need a tan to get that benefit. Ten to 15 minutes of unprotected natural sun exposure on the face and hands 2 to 3 times a week during the summer allows for a healthy dose of vitamin D. Dietary sources, such as low-fat milk, salmon, tuna, and fortified orange juice, are the safest way to get enough vitamin D.

Myth: Indoor tanning is approved by the government.

Fact: According to the Federal Trade Commission, no US government agency recommends the use of indoor tanning equipment. Tanning bed use by minors has been banned in many states, and efforts are ongoing to protect consumers younger than 18 years on local, state, and federal levels. In July 2009, the International Agency for Research on Cancer, part of the World Health Organization, moved tanning devices that emit UV radiation into the highest cancer risk category—carcinogenic to humans—concluding that they are more dangerous than previously thought.

Studies have consistently shown that indoor tanning increases a person’s risk of getting skin cancer and indoor tanning at a young age appears to be more strongly related to lifetime skin cancer risk. Patients should be reminded that every time they tan, they increase their risk of melanoma as well as premature skin aging and other skin cancers. Dermatologists should counsel patients on using sun protection and avoiding indoor tanning.

An 81-year-old woman presented for evaluation of a nodule on the right labia majora that had been present for 1 year. She had a history of intertriginous psoriasis, and several biopsies were performed at an outside facility over the last 5 years that revealed psoriasis but were otherwise noncontributory. Physical examination revealed erythema and scaling on the buttocks with maceration in the intertriginous area (top) and the perineum associated with a verrucous nodule (bottom).

The Diagnosis: Verrucous Carcinoma

Biopsies of early lesions often may be difficult to interpret without clinicopathological correlation. Our patient’s tumor was associated with intertriginous psoriasis, which was the only abnormality previously noted on superficial biopsies performed at an outside facility. The patient was scheduled for an excisional biopsy due to the large tumor size and clinical suspicion that the prior biopsies were inadequate and failed to demonstrate the primary underlying pathology. Excisional biopsy of the verrucous tumor revealed epithelium composed of keratinocytes with glassy cytoplasm. Papillomatosis was noted along with an endophytic component of well-differentiated epithelial cells extending into the dermis in a bulbous pattern consistent with the verrucous carcinoma variant of squamous cell carcinoma (SCC)(Figure). Verrucous carcinoma often requires correlation with both the clinical and histopathologic findings for definitive diagnosis, as keratinocytes often appear to be well differentiated.¹

Excisional biopsy of the verrucous nodule revealed marked acanthosis of the epidermis and bulbous projections of epithelium extending into the dermis. The endophytic “pushing border” supported a diagnosis of verrucous carcinoma (H&amp;E, original magnification ×100).

Verrucous carcinoma may begin as an innocuous papule that slowly grows into a large fungating tumor. Verrucous carcinomas typically are slow growing, exophytic, and low grade. The etiology of verrucous carcinoma is not clear, and the role of human papillomavirus (HPV) infection is controversial.² Best classified as a well-differentiated SCC, verrucous carcinoma rarely metastasizes but may invade adjacent tissues.

Differential diagnoses include a giant inflamed seborrheic keratosis, condyloma acuminatum, rupioid psoriasis, and inflammatory linear verrucous epidermal nevus (ILVEN). Although large and inflamed seborrheic keratoses may have squamous eddies that mimic SCC, seborrheic keratoses do not invade the dermis and typically have a well-circumscribed stuck-on appearance. Abnormal mitotic figures are not identified. Condylomas are genital warts caused by HPV infection that often are clustered, well circumscribed, and exophytic. Large lesions can be difficult to distinguish from verrucous carcinomas, and biopsy generally reveals koilocytes identified by perinuclear clearing and raisinlike nuclei. Immunohistochemical staining and in situ hybridization studies can be of value in diagnosis and in identifying those lesions that are at high risk for malignant transformation. High-risk condylomas are associated with HPV-16, HPV-18, HPV-31, HPV-33, HPV-35, and HPV-39, as well as other types, whereas low-risk condylomas are associated with HPV-6, HPV-11, HPV-42, and others.² Differentiating squamous cell hyperplasia from squamous cell carcinoma in situ also can be aided by immunohistochemistry. Squamous cell hyperplasia is usually negative for INK4 p16^Ink4A and p53 and exhibits variable Ki-67 staining. Differentiated squamous cell carcinoma in situ exhibits a profile that is p16^Ink4A negative, Ki-67 positive, and exhibits variable p53 staining.³ Basaloid and warty intraepithelial neoplasia is consistently p16^Ink4A positive, Ki-67 positive, and variably positive for p53.³ Therefore, p16 staining of high-grade areas is a useful biomarker that can help establish diagnosis of associated squamous cell carcinoma.⁴ The role of papillomaviruses in the development of nonmelanoma skin cancer is an area of active study, and research suggests that papillomaviruses may have a much greater role than previously suspected.⁵

At times, psoriasis may be markedly hyperkeratotic, clinically mimicking a verrucous neoplasm. This hyperkeratotic type of psoriasis is known as rupioid psoriasis. However, these psoriatic lesions are exophytic, are associated with spongiform pustules, and lack the atypia and endophytic pattern typically seen with verrucous carcinoma. An ILVEN also lacks atypia and an endophytic pattern and usually presents in childhood as a persistent linear plaque, rather than the verrucous plaque noted in our patient. Squamous cell carcinoma has been reported to arise in the setting of verrucoid ILVEN but is exceptionally uncommon.⁶

Successful treatment of verrucous carcinoma is best achieved by complete excision. Oral retinoids and immunomodulators such as imiquimod also may be of value.⁷ Our patient’s tumor qualifies as T2N0M0 because it was greater than 2 cm in size.⁸ A Breslow thickness of 2 mm or greater and Clark level IV are high-risk features associated with a worse prognosis, but clinical evaluation of our patient’s lymph nodes was unremarkable and no distant metastases were identified. Our patient continues to do well with no evidence of recurrence.

An 81-year-old woman presented for evaluation of a nodule on the right labia majora that had been present for 1 year. She had a history of intertriginous psoriasis, and several biopsies were performed at an outside facility over the last 5 years that revealed psoriasis but were otherwise noncontributory. Physical examination revealed erythema and scaling on the buttocks with maceration in the intertriginous area (top) and the perineum associated with a verrucous nodule (bottom).

The Diagnosis: Verrucous Carcinoma

Biopsies of early lesions often may be difficult to interpret without clinicopathological correlation. Our patient’s tumor was associated with intertriginous psoriasis, which was the only abnormality previously noted on superficial biopsies performed at an outside facility. The patient was scheduled for an excisional biopsy due to the large tumor size and clinical suspicion that the prior biopsies were inadequate and failed to demonstrate the primary underlying pathology. Excisional biopsy of the verrucous tumor revealed epithelium composed of keratinocytes with glassy cytoplasm. Papillomatosis was noted along with an endophytic component of well-differentiated epithelial cells extending into the dermis in a bulbous pattern consistent with the verrucous carcinoma variant of squamous cell carcinoma (SCC)(Figure). Verrucous carcinoma often requires correlation with both the clinical and histopathologic findings for definitive diagnosis, as keratinocytes often appear to be well differentiated.¹

Excisional biopsy of the verrucous nodule revealed marked acanthosis of the epidermis and bulbous projections of epithelium extending into the dermis. The endophytic “pushing border” supported a diagnosis of verrucous carcinoma (H&amp;E, original magnification ×100).

Verrucous carcinoma may begin as an innocuous papule that slowly grows into a large fungating tumor. Verrucous carcinomas typically are slow growing, exophytic, and low grade. The etiology of verrucous carcinoma is not clear, and the role of human papillomavirus (HPV) infection is controversial.² Best classified as a well-differentiated SCC, verrucous carcinoma rarely metastasizes but may invade adjacent tissues.

Differential diagnoses include a giant inflamed seborrheic keratosis, condyloma acuminatum, rupioid psoriasis, and inflammatory linear verrucous epidermal nevus (ILVEN). Although large and inflamed seborrheic keratoses may have squamous eddies that mimic SCC, seborrheic keratoses do not invade the dermis and typically have a well-circumscribed stuck-on appearance. Abnormal mitotic figures are not identified. Condylomas are genital warts caused by HPV infection that often are clustered, well circumscribed, and exophytic. Large lesions can be difficult to distinguish from verrucous carcinomas, and biopsy generally reveals koilocytes identified by perinuclear clearing and raisinlike nuclei. Immunohistochemical staining and in situ hybridization studies can be of value in diagnosis and in identifying those lesions that are at high risk for malignant transformation. High-risk condylomas are associated with HPV-16, HPV-18, HPV-31, HPV-33, HPV-35, and HPV-39, as well as other types, whereas low-risk condylomas are associated with HPV-6, HPV-11, HPV-42, and others.² Differentiating squamous cell hyperplasia from squamous cell carcinoma in situ also can be aided by immunohistochemistry. Squamous cell hyperplasia is usually negative for INK4 p16^Ink4A and p53 and exhibits variable Ki-67 staining. Differentiated squamous cell carcinoma in situ exhibits a profile that is p16^Ink4A negative, Ki-67 positive, and exhibits variable p53 staining.³ Basaloid and warty intraepithelial neoplasia is consistently p16^Ink4A positive, Ki-67 positive, and variably positive for p53.³ Therefore, p16 staining of high-grade areas is a useful biomarker that can help establish diagnosis of associated squamous cell carcinoma.⁴ The role of papillomaviruses in the development of nonmelanoma skin cancer is an area of active study, and research suggests that papillomaviruses may have a much greater role than previously suspected.⁵

At times, psoriasis may be markedly hyperkeratotic, clinically mimicking a verrucous neoplasm. This hyperkeratotic type of psoriasis is known as rupioid psoriasis. However, these psoriatic lesions are exophytic, are associated with spongiform pustules, and lack the atypia and endophytic pattern typically seen with verrucous carcinoma. An ILVEN also lacks atypia and an endophytic pattern and usually presents in childhood as a persistent linear plaque, rather than the verrucous plaque noted in our patient. Squamous cell carcinoma has been reported to arise in the setting of verrucoid ILVEN but is exceptionally uncommon.⁶

Successful treatment of verrucous carcinoma is best achieved by complete excision. Oral retinoids and immunomodulators such as imiquimod also may be of value.⁷ Our patient’s tumor qualifies as T2N0M0 because it was greater than 2 cm in size.⁸ A Breslow thickness of 2 mm or greater and Clark level IV are high-risk features associated with a worse prognosis, but clinical evaluation of our patient’s lymph nodes was unremarkable and no distant metastases were identified. Our patient continues to do well with no evidence of recurrence.

An 81-year-old woman presented for evaluation of a nodule on the right labia majora that had been present for 1 year. She had a history of intertriginous psoriasis, and several biopsies were performed at an outside facility over the last 5 years that revealed psoriasis but were otherwise noncontributory. Physical examination revealed erythema and scaling on the buttocks with maceration in the intertriginous area (top) and the perineum associated with a verrucous nodule (bottom).

The Diagnosis: Verrucous Carcinoma

Biopsies of early lesions often may be difficult to interpret without clinicopathological correlation. Our patient’s tumor was associated with intertriginous psoriasis, which was the only abnormality previously noted on superficial biopsies performed at an outside facility. The patient was scheduled for an excisional biopsy due to the large tumor size and clinical suspicion that the prior biopsies were inadequate and failed to demonstrate the primary underlying pathology. Excisional biopsy of the verrucous tumor revealed epithelium composed of keratinocytes with glassy cytoplasm. Papillomatosis was noted along with an endophytic component of well-differentiated epithelial cells extending into the dermis in a bulbous pattern consistent with the verrucous carcinoma variant of squamous cell carcinoma (SCC)(Figure). Verrucous carcinoma often requires correlation with both the clinical and histopathologic findings for definitive diagnosis, as keratinocytes often appear to be well differentiated.¹

Excisional biopsy of the verrucous nodule revealed marked acanthosis of the epidermis and bulbous projections of epithelium extending into the dermis. The endophytic “pushing border” supported a diagnosis of verrucous carcinoma (H&amp;E, original magnification ×100).

Verrucous carcinoma may begin as an innocuous papule that slowly grows into a large fungating tumor. Verrucous carcinomas typically are slow growing, exophytic, and low grade. The etiology of verrucous carcinoma is not clear, and the role of human papillomavirus (HPV) infection is controversial.² Best classified as a well-differentiated SCC, verrucous carcinoma rarely metastasizes but may invade adjacent tissues.

Differential diagnoses include a giant inflamed seborrheic keratosis, condyloma acuminatum, rupioid psoriasis, and inflammatory linear verrucous epidermal nevus (ILVEN). Although large and inflamed seborrheic keratoses may have squamous eddies that mimic SCC, seborrheic keratoses do not invade the dermis and typically have a well-circumscribed stuck-on appearance. Abnormal mitotic figures are not identified. Condylomas are genital warts caused by HPV infection that often are clustered, well circumscribed, and exophytic. Large lesions can be difficult to distinguish from verrucous carcinomas, and biopsy generally reveals koilocytes identified by perinuclear clearing and raisinlike nuclei. Immunohistochemical staining and in situ hybridization studies can be of value in diagnosis and in identifying those lesions that are at high risk for malignant transformation. High-risk condylomas are associated with HPV-16, HPV-18, HPV-31, HPV-33, HPV-35, and HPV-39, as well as other types, whereas low-risk condylomas are associated with HPV-6, HPV-11, HPV-42, and others.² Differentiating squamous cell hyperplasia from squamous cell carcinoma in situ also can be aided by immunohistochemistry. Squamous cell hyperplasia is usually negative for INK4 p16^Ink4A and p53 and exhibits variable Ki-67 staining. Differentiated squamous cell carcinoma in situ exhibits a profile that is p16^Ink4A negative, Ki-67 positive, and exhibits variable p53 staining.³ Basaloid and warty intraepithelial neoplasia is consistently p16^Ink4A positive, Ki-67 positive, and variably positive for p53.³ Therefore, p16 staining of high-grade areas is a useful biomarker that can help establish diagnosis of associated squamous cell carcinoma.⁴ The role of papillomaviruses in the development of nonmelanoma skin cancer is an area of active study, and research suggests that papillomaviruses may have a much greater role than previously suspected.⁵

At times, psoriasis may be markedly hyperkeratotic, clinically mimicking a verrucous neoplasm. This hyperkeratotic type of psoriasis is known as rupioid psoriasis. However, these psoriatic lesions are exophytic, are associated with spongiform pustules, and lack the atypia and endophytic pattern typically seen with verrucous carcinoma. An ILVEN also lacks atypia and an endophytic pattern and usually presents in childhood as a persistent linear plaque, rather than the verrucous plaque noted in our patient. Squamous cell carcinoma has been reported to arise in the setting of verrucoid ILVEN but is exceptionally uncommon.⁶

Successful treatment of verrucous carcinoma is best achieved by complete excision. Oral retinoids and immunomodulators such as imiquimod also may be of value.⁷ Our patient’s tumor qualifies as T2N0M0 because it was greater than 2 cm in size.⁸ A Breslow thickness of 2 mm or greater and Clark level IV are high-risk features associated with a worse prognosis, but clinical evaluation of our patient’s lymph nodes was unremarkable and no distant metastases were identified. Our patient continues to do well with no evidence of recurrence.

Martin et al recently presented a study at the 2015 American Society of Clinical Oncology Annual Meeting (J Clin Oncol. 2015;33[suppl]:9000) that reported on a phase 3 double-blind randomized trial to assess the use of oral nicotinamide to reduce actinic skin cancers, namely basal cell carcinoma (BCC) and squamous cell carcinoma (SCC).

This study was conducted in 2 tertiary treatment centers in Sydney, Australia, from 2012 to 2014, and it included 386 immunocompetent participants with 2 or more histologically confirmed nonmelanoma skin cancers (NMSCs) in the last 5 years. Two groups were randomized (1:1 ratio) to either receive oral nicotinamide 500 mg twice daily or matched placebo for 12 months. The primary end point measured was the number of new NMSCs to 12 months. Other secondary end points included number of SCCs, BCCs, and actinic keratoses to 12 months. Dermatologists performed skin checks every 3 months on the participants.

The results of the study showed that the average NMSC rate was significantly lower for the oral nicotinamide group (1.77) compared to the placebo group (2.42). The estimated relative rate reduction (RRR) was 0.23 (95% confidence interval [CI], 0.04-0.38; P=.02) adjusting for center and NMSC history, and 0.27 (95% CI, 0.05-0.44; P=.02) with no adjustment. The effects for BCC were comparable to SCC: BCC (RRR, 0.20; 95% CI, -0.06 to 0.39; P=.1) and SCC (RRR, 0.30; 95% CI, 0-0.51; P=.05). Additionally, actinic keratosis counts were reduced by 11% at 3 months (P=.01), 14% at 6 months (P<.001), 20% at 9 months (P<.0001), and 13% at 12 months (P<.005) for the oral nicotinamide group compared to the placebo group. There was no difference in the adverse event rates between the 2 groups.

What’s the issue?

This study reported the results of a double-blind randomized study of nicotinamide (vitamin B₃) to reduce actinic cancer, called the ONTRAC (Oral Nicotinamide to Reduce Actinic Cancer) study, with favorable results for the use of oral nicotinamide, an inexpensive vitamin. There was a 20% reduction in BCC and a 30% reduction in SCC in the nicotinamide group compared to the group taking a placebo with no active ingredients. This study was conducted in a heavily sun-damaged group and it is postulated that nicotinamide helps cells repair DNA damage.

The thought of using a vitamin to reduce skin cancer rates is exciting; however, this study is singular, and while it did show promising results, the number of participants is not very large. There also was no evidence that nicotinamide prevents melanoma formation. Also, there was no protective effect seen once the vitamin B₃ treatment was stopped. One must be cognizant that nicotinamide is not interchangeable with other forms of vitamin B₃ such as niacin.

Although this study is promising, more research is needed to determine nicotinamide’s preventative effects. Of course, strict sun protection and skin checks are the first line in the prevention of skin cancer. Will you be prescribing oral nicotinamide to your patients to prevent NMSC?

We want to know your views! Tell us what you think.

Martin et al recently presented a study at the 2015 American Society of Clinical Oncology Annual Meeting (J Clin Oncol. 2015;33[suppl]:9000) that reported on a phase 3 double-blind randomized trial to assess the use of oral nicotinamide to reduce actinic skin cancers, namely basal cell carcinoma (BCC) and squamous cell carcinoma (SCC).

This study was conducted in 2 tertiary treatment centers in Sydney, Australia, from 2012 to 2014, and it included 386 immunocompetent participants with 2 or more histologically confirmed nonmelanoma skin cancers (NMSCs) in the last 5 years. Two groups were randomized (1:1 ratio) to either receive oral nicotinamide 500 mg twice daily or matched placebo for 12 months. The primary end point measured was the number of new NMSCs to 12 months. Other secondary end points included number of SCCs, BCCs, and actinic keratoses to 12 months. Dermatologists performed skin checks every 3 months on the participants.

The results of the study showed that the average NMSC rate was significantly lower for the oral nicotinamide group (1.77) compared to the placebo group (2.42). The estimated relative rate reduction (RRR) was 0.23 (95% confidence interval [CI], 0.04-0.38; P=.02) adjusting for center and NMSC history, and 0.27 (95% CI, 0.05-0.44; P=.02) with no adjustment. The effects for BCC were comparable to SCC: BCC (RRR, 0.20; 95% CI, -0.06 to 0.39; P=.1) and SCC (RRR, 0.30; 95% CI, 0-0.51; P=.05). Additionally, actinic keratosis counts were reduced by 11% at 3 months (P=.01), 14% at 6 months (P<.001), 20% at 9 months (P<.0001), and 13% at 12 months (P<.005) for the oral nicotinamide group compared to the placebo group. There was no difference in the adverse event rates between the 2 groups.

What’s the issue?

This study reported the results of a double-blind randomized study of nicotinamide (vitamin B₃) to reduce actinic cancer, called the ONTRAC (Oral Nicotinamide to Reduce Actinic Cancer) study, with favorable results for the use of oral nicotinamide, an inexpensive vitamin. There was a 20% reduction in BCC and a 30% reduction in SCC in the nicotinamide group compared to the group taking a placebo with no active ingredients. This study was conducted in a heavily sun-damaged group and it is postulated that nicotinamide helps cells repair DNA damage.

The thought of using a vitamin to reduce skin cancer rates is exciting; however, this study is singular, and while it did show promising results, the number of participants is not very large. There also was no evidence that nicotinamide prevents melanoma formation. Also, there was no protective effect seen once the vitamin B₃ treatment was stopped. One must be cognizant that nicotinamide is not interchangeable with other forms of vitamin B₃ such as niacin.

Although this study is promising, more research is needed to determine nicotinamide’s preventative effects. Of course, strict sun protection and skin checks are the first line in the prevention of skin cancer. Will you be prescribing oral nicotinamide to your patients to prevent NMSC?

We want to know your views! Tell us what you think.

Martin et al recently presented a study at the 2015 American Society of Clinical Oncology Annual Meeting (J Clin Oncol. 2015;33[suppl]:9000) that reported on a phase 3 double-blind randomized trial to assess the use of oral nicotinamide to reduce actinic skin cancers, namely basal cell carcinoma (BCC) and squamous cell carcinoma (SCC).

This study was conducted in 2 tertiary treatment centers in Sydney, Australia, from 2012 to 2014, and it included 386 immunocompetent participants with 2 or more histologically confirmed nonmelanoma skin cancers (NMSCs) in the last 5 years. Two groups were randomized (1:1 ratio) to either receive oral nicotinamide 500 mg twice daily or matched placebo for 12 months. The primary end point measured was the number of new NMSCs to 12 months. Other secondary end points included number of SCCs, BCCs, and actinic keratoses to 12 months. Dermatologists performed skin checks every 3 months on the participants.

The results of the study showed that the average NMSC rate was significantly lower for the oral nicotinamide group (1.77) compared to the placebo group (2.42). The estimated relative rate reduction (RRR) was 0.23 (95% confidence interval [CI], 0.04-0.38; P=.02) adjusting for center and NMSC history, and 0.27 (95% CI, 0.05-0.44; P=.02) with no adjustment. The effects for BCC were comparable to SCC: BCC (RRR, 0.20; 95% CI, -0.06 to 0.39; P=.1) and SCC (RRR, 0.30; 95% CI, 0-0.51; P=.05). Additionally, actinic keratosis counts were reduced by 11% at 3 months (P=.01), 14% at 6 months (P<.001), 20% at 9 months (P<.0001), and 13% at 12 months (P<.005) for the oral nicotinamide group compared to the placebo group. There was no difference in the adverse event rates between the 2 groups.

What’s the issue?

This study reported the results of a double-blind randomized study of nicotinamide (vitamin B₃) to reduce actinic cancer, called the ONTRAC (Oral Nicotinamide to Reduce Actinic Cancer) study, with favorable results for the use of oral nicotinamide, an inexpensive vitamin. There was a 20% reduction in BCC and a 30% reduction in SCC in the nicotinamide group compared to the group taking a placebo with no active ingredients. This study was conducted in a heavily sun-damaged group and it is postulated that nicotinamide helps cells repair DNA damage.

The thought of using a vitamin to reduce skin cancer rates is exciting; however, this study is singular, and while it did show promising results, the number of participants is not very large. There also was no evidence that nicotinamide prevents melanoma formation. Also, there was no protective effect seen once the vitamin B₃ treatment was stopped. One must be cognizant that nicotinamide is not interchangeable with other forms of vitamin B₃ such as niacin.

Although this study is promising, more research is needed to determine nicotinamide’s preventative effects. Of course, strict sun protection and skin checks are the first line in the prevention of skin cancer. Will you be prescribing oral nicotinamide to your patients to prevent NMSC?

We want to know your views! Tell us what you think.