Dermatopathology

Background and Clinical Presentation

Seabather’s Eruption—Seabather’s eruption is a type I and IV hypersensitivity reaction caused by nematocysts of larval-stage thimble jellyfish (Linuche unguiculata), sea anemones (eg, Edwardsiella lineata), and larval cnidarians.¹Linuche unguiculata commonly is found along the southeast coast of the United States and in the Caribbean, the Gulf of Mexico, and the coasts of Florida; less commonly, it has been reported along the coasts of Brazil and Papua New Guinea. Edwardsiella lineata more commonly is seen along the East Coast of the United States.² Seabather’s eruption presents as numerous scattered, pruritic, red macules and papules (measuring 1 mm to 1.5 cm in size) distributed in areas covered by skin folds, wet clothing, or hair following exposure to marine water (Figure 1). This maculopapular rash generally appears shortly after exiting the water and can last up to several weeks in some cases.³ The cause for this delayed presentation is that the marine organisms become entrapped between the skin of the human contact and another object (eg, swimwear) but do not release their preformed antivenom until they are exposed to air after removal from the water, at which point the organisms die and cell lysis results in injection of the venom.

Diver’s Dermatitis—Diver’s dermatitis (also referred to as “swimmer’s itch”) is a type I and IV hypersensitivity reaction caused by schistosome cercariae released by aquatic snails.⁴ There are several different cercarial species known to be capable of causing diver dermatitis, but the most commonly implicated genera are Trichobilharzia and Gigantobilharzia. These parasites most commonly are found in freshwater lakes but also occur in oceans, particularly in brackish areas adjacent to freshwater access. Factors associated with increased concentrations of these parasites include shallow, slow-moving water and prolonged onshore wind causing accumulation near the shoreline. It also is thought that the snail host will shed greater concentrations of the parasitic worm in the morning hours and after prolonged exposure to sunlight.⁴ These flatworm trematodes have a 2-host life cycle. The snails function as intermediate hosts for the parasites before they enter their final host, which are birds. Humans only function as incidental and nonviable hosts for these worms. The parasites gain access to the human body by burrowing into exposed skin. Because the parasite is unable to survive on human hosts, it dies shortly after penetrating the skin, which leads to an intense inflammatory response causing symptoms of pruritus within hours of exposure (Figure 2). The initial eruption progresses over a few days into a diffuse, maculopapular, pruritic rash, similar to that seen in seabather’s eruption. This rash then regresses completely in 1 to 3 weeks. Subsequent exposure to the same parasite is associated with increased severity of future rashes, likely due to antibody-mediated sensitization.⁴

Photograph courtesy of Tomas Machacek, PhD (Prague, Czechia).

Diagnosis—Marine-derived dermatoses from various sources can present very similarly; thus, it is difficult to discern the specific etiology behind the clinical presentation. No commonly utilized imaging modalities can differentiate between seabather’s eruption and diver’s dermatitis, but eliciting a thorough patient history often can aid in differentiation of the cause of the eruption. For example, lesions located only on nonexposed areas of the skin increases the likelihood of seabather’s eruption due to nematocysts being trapped between clothing and the skin. In contrast, diver’s dermatitis generally appears on areas of the skin that were directly exposed to water and uncovered by clothing.⁵ Patient reports of a lack of symptoms until shortly after exiting the water further support a diagnosis of seabather’s eruption, as this delayed presentation of symptoms is caused by lysis of the culprit organisms following removal from the marine environment. The cell lysis is responsible for the widespread injection of preformed venom via the numerous nematocysts trapped between clothing and the patient’s body.¹

Treatment

For both conditions, the symptoms are treated with hydrocortisone or other topical steroid solutions in conjunction with oral hydroxyzine. Alternative treatments include calamine lotion with 1% menthol and nonsteroidal anti-inflammatory drugs. Taking baths with oatmeal, Epsom salts, or baking soda also may alleviate some of the pruritic symptoms.²

Prevention

The ability to diagnose the precise cause of these similar marine rashes can bring peace of mind to both patients and physicians regardless of their similar management strategies. Severe contact dermatitis of unknown etiology can be disconcerting for patients. Additionally, documenting the causes of marine rashes in particular geographic locations can be beneficial for establishing which organisms are most likely to affect visitors to those areas. This type of data collection can be utilized to develop preventative recommendations, such as deciding when to avoid the water. Education of the public can be done with the use of informational posters located near popular swimming areas and online public service announcements. Informing the general public about the dangers of entering the ocean, especially during certain times of the year when nematocyst-equipped sea creatures are in abundance, could serve to prevent numerous cases of seabather’s eruption. Likewise, advising against immersion in shallow, slow-moving water during the morning hours or after prolonged sun exposure in trematode-endemic areas could prevent numerous cases of diver’s dermatitis. Basic information on what to expect if afflicted by a marine rash also may reduce the number of emergency department visits for these conditions, thus providing economic benefit for patients and for hospitals since patients would better know how to acutely treat these rashes and lessen the patient load at hospital emergency departments. If individuals can assure themselves of the self-limited nature of these types of dermatoses, they may be less inclined to seek medical consultation.

Final Thoughts

As the climate continues to change, the incidence of marine rashes such as seabather’s eruption and diver’s dermatitis is expected to increase due to warmer surface temperatures causing more frequent and earlier blooms of L unguiculata and E lineata. Cases of diver’s dermatitis also could increase due to a longer season of more frequent human exposure from an increase in warmer temperatures. The projected uptick in incidences of these marine rashes makes understanding these pathologies even more pertinent for physicians.⁶ Increasing our understanding of the different types of marine rashes and their causes will help guide future recommendations for the general public when visiting the ocean.

Future research may wish to investigate unique ways in which to prevent contact between these organisms and humans. Past research on mice indicated that topical application of DEET (N,N-diethyl-meta-toluamide) prior to trematode exposure prevented penetration of the skin by parasitic worms.⁷ Future studies are needed to examine the effectiveness of this preventative technique on humans. For now, dermatologists may counsel our ocean-going patients on preventative behaviors as well as provide reassurance and symptomatic relief when they present to our clinics with marine rashes.

Background and Clinical Presentation

Seabather’s Eruption—Seabather’s eruption is a type I and IV hypersensitivity reaction caused by nematocysts of larval-stage thimble jellyfish (Linuche unguiculata), sea anemones (eg, Edwardsiella lineata), and larval cnidarians.¹Linuche unguiculata commonly is found along the southeast coast of the United States and in the Caribbean, the Gulf of Mexico, and the coasts of Florida; less commonly, it has been reported along the coasts of Brazil and Papua New Guinea. Edwardsiella lineata more commonly is seen along the East Coast of the United States.² Seabather’s eruption presents as numerous scattered, pruritic, red macules and papules (measuring 1 mm to 1.5 cm in size) distributed in areas covered by skin folds, wet clothing, or hair following exposure to marine water (Figure 1). This maculopapular rash generally appears shortly after exiting the water and can last up to several weeks in some cases.³ The cause for this delayed presentation is that the marine organisms become entrapped between the skin of the human contact and another object (eg, swimwear) but do not release their preformed antivenom until they are exposed to air after removal from the water, at which point the organisms die and cell lysis results in injection of the venom.

Diver’s Dermatitis—Diver’s dermatitis (also referred to as “swimmer’s itch”) is a type I and IV hypersensitivity reaction caused by schistosome cercariae released by aquatic snails.⁴ There are several different cercarial species known to be capable of causing diver dermatitis, but the most commonly implicated genera are Trichobilharzia and Gigantobilharzia. These parasites most commonly are found in freshwater lakes but also occur in oceans, particularly in brackish areas adjacent to freshwater access. Factors associated with increased concentrations of these parasites include shallow, slow-moving water and prolonged onshore wind causing accumulation near the shoreline. It also is thought that the snail host will shed greater concentrations of the parasitic worm in the morning hours and after prolonged exposure to sunlight.⁴ These flatworm trematodes have a 2-host life cycle. The snails function as intermediate hosts for the parasites before they enter their final host, which are birds. Humans only function as incidental and nonviable hosts for these worms. The parasites gain access to the human body by burrowing into exposed skin. Because the parasite is unable to survive on human hosts, it dies shortly after penetrating the skin, which leads to an intense inflammatory response causing symptoms of pruritus within hours of exposure (Figure 2). The initial eruption progresses over a few days into a diffuse, maculopapular, pruritic rash, similar to that seen in seabather’s eruption. This rash then regresses completely in 1 to 3 weeks. Subsequent exposure to the same parasite is associated with increased severity of future rashes, likely due to antibody-mediated sensitization.⁴

Photograph courtesy of Tomas Machacek, PhD (Prague, Czechia).

Diagnosis—Marine-derived dermatoses from various sources can present very similarly; thus, it is difficult to discern the specific etiology behind the clinical presentation. No commonly utilized imaging modalities can differentiate between seabather’s eruption and diver’s dermatitis, but eliciting a thorough patient history often can aid in differentiation of the cause of the eruption. For example, lesions located only on nonexposed areas of the skin increases the likelihood of seabather’s eruption due to nematocysts being trapped between clothing and the skin. In contrast, diver’s dermatitis generally appears on areas of the skin that were directly exposed to water and uncovered by clothing.⁵ Patient reports of a lack of symptoms until shortly after exiting the water further support a diagnosis of seabather’s eruption, as this delayed presentation of symptoms is caused by lysis of the culprit organisms following removal from the marine environment. The cell lysis is responsible for the widespread injection of preformed venom via the numerous nematocysts trapped between clothing and the patient’s body.¹

Treatment

For both conditions, the symptoms are treated with hydrocortisone or other topical steroid solutions in conjunction with oral hydroxyzine. Alternative treatments include calamine lotion with 1% menthol and nonsteroidal anti-inflammatory drugs. Taking baths with oatmeal, Epsom salts, or baking soda also may alleviate some of the pruritic symptoms.²

Prevention

The ability to diagnose the precise cause of these similar marine rashes can bring peace of mind to both patients and physicians regardless of their similar management strategies. Severe contact dermatitis of unknown etiology can be disconcerting for patients. Additionally, documenting the causes of marine rashes in particular geographic locations can be beneficial for establishing which organisms are most likely to affect visitors to those areas. This type of data collection can be utilized to develop preventative recommendations, such as deciding when to avoid the water. Education of the public can be done with the use of informational posters located near popular swimming areas and online public service announcements. Informing the general public about the dangers of entering the ocean, especially during certain times of the year when nematocyst-equipped sea creatures are in abundance, could serve to prevent numerous cases of seabather’s eruption. Likewise, advising against immersion in shallow, slow-moving water during the morning hours or after prolonged sun exposure in trematode-endemic areas could prevent numerous cases of diver’s dermatitis. Basic information on what to expect if afflicted by a marine rash also may reduce the number of emergency department visits for these conditions, thus providing economic benefit for patients and for hospitals since patients would better know how to acutely treat these rashes and lessen the patient load at hospital emergency departments. If individuals can assure themselves of the self-limited nature of these types of dermatoses, they may be less inclined to seek medical consultation.

Final Thoughts

As the climate continues to change, the incidence of marine rashes such as seabather’s eruption and diver’s dermatitis is expected to increase due to warmer surface temperatures causing more frequent and earlier blooms of L unguiculata and E lineata. Cases of diver’s dermatitis also could increase due to a longer season of more frequent human exposure from an increase in warmer temperatures. The projected uptick in incidences of these marine rashes makes understanding these pathologies even more pertinent for physicians.⁶ Increasing our understanding of the different types of marine rashes and their causes will help guide future recommendations for the general public when visiting the ocean.

Future research may wish to investigate unique ways in which to prevent contact between these organisms and humans. Past research on mice indicated that topical application of DEET (N,N-diethyl-meta-toluamide) prior to trematode exposure prevented penetration of the skin by parasitic worms.⁷ Future studies are needed to examine the effectiveness of this preventative technique on humans. For now, dermatologists may counsel our ocean-going patients on preventative behaviors as well as provide reassurance and symptomatic relief when they present to our clinics with marine rashes.

Background and Clinical Presentation

Seabather’s Eruption—Seabather’s eruption is a type I and IV hypersensitivity reaction caused by nematocysts of larval-stage thimble jellyfish (Linuche unguiculata), sea anemones (eg, Edwardsiella lineata), and larval cnidarians.¹Linuche unguiculata commonly is found along the southeast coast of the United States and in the Caribbean, the Gulf of Mexico, and the coasts of Florida; less commonly, it has been reported along the coasts of Brazil and Papua New Guinea. Edwardsiella lineata more commonly is seen along the East Coast of the United States.² Seabather’s eruption presents as numerous scattered, pruritic, red macules and papules (measuring 1 mm to 1.5 cm in size) distributed in areas covered by skin folds, wet clothing, or hair following exposure to marine water (Figure 1). This maculopapular rash generally appears shortly after exiting the water and can last up to several weeks in some cases.³ The cause for this delayed presentation is that the marine organisms become entrapped between the skin of the human contact and another object (eg, swimwear) but do not release their preformed antivenom until they are exposed to air after removal from the water, at which point the organisms die and cell lysis results in injection of the venom.

Diver’s Dermatitis—Diver’s dermatitis (also referred to as “swimmer’s itch”) is a type I and IV hypersensitivity reaction caused by schistosome cercariae released by aquatic snails.⁴ There are several different cercarial species known to be capable of causing diver dermatitis, but the most commonly implicated genera are Trichobilharzia and Gigantobilharzia. These parasites most commonly are found in freshwater lakes but also occur in oceans, particularly in brackish areas adjacent to freshwater access. Factors associated with increased concentrations of these parasites include shallow, slow-moving water and prolonged onshore wind causing accumulation near the shoreline. It also is thought that the snail host will shed greater concentrations of the parasitic worm in the morning hours and after prolonged exposure to sunlight.⁴ These flatworm trematodes have a 2-host life cycle. The snails function as intermediate hosts for the parasites before they enter their final host, which are birds. Humans only function as incidental and nonviable hosts for these worms. The parasites gain access to the human body by burrowing into exposed skin. Because the parasite is unable to survive on human hosts, it dies shortly after penetrating the skin, which leads to an intense inflammatory response causing symptoms of pruritus within hours of exposure (Figure 2). The initial eruption progresses over a few days into a diffuse, maculopapular, pruritic rash, similar to that seen in seabather’s eruption. This rash then regresses completely in 1 to 3 weeks. Subsequent exposure to the same parasite is associated with increased severity of future rashes, likely due to antibody-mediated sensitization.⁴

Photograph courtesy of Tomas Machacek, PhD (Prague, Czechia).

Diagnosis—Marine-derived dermatoses from various sources can present very similarly; thus, it is difficult to discern the specific etiology behind the clinical presentation. No commonly utilized imaging modalities can differentiate between seabather’s eruption and diver’s dermatitis, but eliciting a thorough patient history often can aid in differentiation of the cause of the eruption. For example, lesions located only on nonexposed areas of the skin increases the likelihood of seabather’s eruption due to nematocysts being trapped between clothing and the skin. In contrast, diver’s dermatitis generally appears on areas of the skin that were directly exposed to water and uncovered by clothing.⁵ Patient reports of a lack of symptoms until shortly after exiting the water further support a diagnosis of seabather’s eruption, as this delayed presentation of symptoms is caused by lysis of the culprit organisms following removal from the marine environment. The cell lysis is responsible for the widespread injection of preformed venom via the numerous nematocysts trapped between clothing and the patient’s body.¹

Treatment

For both conditions, the symptoms are treated with hydrocortisone or other topical steroid solutions in conjunction with oral hydroxyzine. Alternative treatments include calamine lotion with 1% menthol and nonsteroidal anti-inflammatory drugs. Taking baths with oatmeal, Epsom salts, or baking soda also may alleviate some of the pruritic symptoms.²

Prevention

The ability to diagnose the precise cause of these similar marine rashes can bring peace of mind to both patients and physicians regardless of their similar management strategies. Severe contact dermatitis of unknown etiology can be disconcerting for patients. Additionally, documenting the causes of marine rashes in particular geographic locations can be beneficial for establishing which organisms are most likely to affect visitors to those areas. This type of data collection can be utilized to develop preventative recommendations, such as deciding when to avoid the water. Education of the public can be done with the use of informational posters located near popular swimming areas and online public service announcements. Informing the general public about the dangers of entering the ocean, especially during certain times of the year when nematocyst-equipped sea creatures are in abundance, could serve to prevent numerous cases of seabather’s eruption. Likewise, advising against immersion in shallow, slow-moving water during the morning hours or after prolonged sun exposure in trematode-endemic areas could prevent numerous cases of diver’s dermatitis. Basic information on what to expect if afflicted by a marine rash also may reduce the number of emergency department visits for these conditions, thus providing economic benefit for patients and for hospitals since patients would better know how to acutely treat these rashes and lessen the patient load at hospital emergency departments. If individuals can assure themselves of the self-limited nature of these types of dermatoses, they may be less inclined to seek medical consultation.

Final Thoughts

As the climate continues to change, the incidence of marine rashes such as seabather’s eruption and diver’s dermatitis is expected to increase due to warmer surface temperatures causing more frequent and earlier blooms of L unguiculata and E lineata. Cases of diver’s dermatitis also could increase due to a longer season of more frequent human exposure from an increase in warmer temperatures. The projected uptick in incidences of these marine rashes makes understanding these pathologies even more pertinent for physicians.⁶ Increasing our understanding of the different types of marine rashes and their causes will help guide future recommendations for the general public when visiting the ocean.

Future research may wish to investigate unique ways in which to prevent contact between these organisms and humans. Past research on mice indicated that topical application of DEET (N,N-diethyl-meta-toluamide) prior to trematode exposure prevented penetration of the skin by parasitic worms.⁷ Future studies are needed to examine the effectiveness of this preventative technique on humans. For now, dermatologists may counsel our ocean-going patients on preventative behaviors as well as provide reassurance and symptomatic relief when they present to our clinics with marine rashes.

The Diagnosis: Metastatic Clear Cell Renal Cell Carcinoma

Renal cell carcinoma (RCC) is a common genitourinary system malignancy with incidence peaking between 50 and 70 years of age and a male predominance.¹ The clear cell variant is the most common subtype of RCC, accounting for 70% to 75% of all cases. It is known to be a highly aggressive malignancy that frequently metastasizes to the lungs, lymphatics, bones, liver, and brain.^2,3 Approximately 20% to 50% of patients with RCC eventually will develop metastasis after nephrectomy.⁴ Survival with metastatic RCC to any site typically is in the range of 10 to 22 months.^5,6 Cutaneous metastases of RCC rarely have been reported in the literature (3%–6% of cases⁷) and most commonly are found on the scalp, followed by the chest or abdomen. ⁸ Cutaneous metastases generally are regarded as a late manifestation of the disease with a very poor prognosis. ⁹ It is unusual to identify cutaneous RCC metastasis without known RCC or other symptoms consistent with advanced RCC, such as hematuria or abdominal/flank pain. Renal cell carcinoma accounts for an estimated 6% to 7% of all cutaneous metastatic lesions.¹⁰ Cutaneous metastatic lesions of RCC often are solitary and grow rapidly, with the clinical appearance of an erythematous or violaceous, nodular, highly vascular, and often hemorrhagic growth.^9,11,12

Following the histologic diagnosis of metastatic clear cell RCC, our patient was referred to medical oncology for further workup. Magnetic resonance imaging and a positron emission tomography scan demonstrated widespread disease with a 7-cm left renal mass, liver and lung metastases, and bilateral mediastinal lymphadenopathy. The patient was started on combination immunotherapy as a palliative treatment given the widespread disease.

Histologically, clear cell RCC is characterized by lipid and glycogen-rich cells with ample cytoplasm and a well-developed vascular network, which often is thin walled with a chicken wire–like architecture. Metastatic clear cell RCC tumor cells may form glandular, acinar, or papillary structures with variable lymphocytic inflammatory infiltrates and abundant capillary formation. Immunohistochemically, the tumor cells should demonstrate positivity for paired box gene 8, PAX8, and RCC marker antigen.¹³ Vimentin and carcinoembryonic antigen may be utilized to distinguish from hidradenoma as carcinoembryonic antigen will be positive in hidradenoma and vimentin will be negative.¹⁴ Renal cell carcinoma also has a common molecular signature of von Hippel-Lindau tumor suppressor gene inactivation as well as upregulation of hypoxia inducible factor and vascular endothelial growth factor.¹⁵

Balloon cell nevi often clinically present in young patients as bicolored nevi that sometimes are polypoid or verrucous in appearance with central yellow globules surrounded by a peripheral reticular pattern on dermoscopy. Histologically, balloon cell nevi are characterized by large cells with small, round, centrally located basophilic nuclei and clear foamy cytoplasm (Figure 1), which are thought to be formed by progressive vacuolization of melanocytes due to the enlargement and disintegration of melanosomes. This ballooning change reflects an seen in malignant melanoma, in which case nuclear pleomorphism, atypia, and increased mitotic activity also are observed. The prominent vascular network characteristic of RCC typically is not present.¹⁶

Clear cell hidradenomas are benign skin appendage tumors that often present as small, firm, solitary dermal nodules that may extend into the subcutaneous fat. They have a predilection for the head, face, and arms and demonstrate 2 predominant cell types, including a polyhedral cell with a rounded nucleus and slightly basophilic cytoplasm as well as a round cell with clear cytoplasm and bland nuclei (Figure 2). The latter cell type is less common, representing the predominant cell type in less than one-third of hidradenomas, and can present a diagnostic quandary based on histologic similarity to other clear cell neoplasms. The clear cells contain glycogen but no lipid. Ductlike structures often are present, and the intervening stroma varies from delicate vascularized cords of fibrous tissue to dense hyalinized collagen. Immunohistochemistry may be required for definitive diagnosis, and clear cell hidradenomas should react with monoclonal antibodies that label both eccrine and apocrine secretory elements, such as cytokeratins 6/18, 7, and 8/18.¹⁷

Pyogenic granulomas (also referred to as lobular capillary hemangiomas) are common and present clinically as rapidly growing, polypoid, red masses surrounded by a thickened epidermis that often are found on the fingers or lips. This entity is benign and often regresses spontaneously. Histologically, pyogenic granulomas are characterized by a lobular pattern of vascular proliferation associated with edema and inflammation resembling granulation tissue, with acanthosis and hyperkeratosis at the edges of the lesion (Figure 3).¹⁸

Sebaceous carcinoma is a locally aggressive malignant neoplasm arising from the cells of the sebaceous glands and occurring most commonly in the periorbital area. This neoplasm most often affects older adults, with a mean age at diagnosis of 63 to 77 years. It commonly presents as a solitary nodule with yellowish discoloration and madarosis, which is a key distinguishing feature to differentiate this entity from a chalazion or hordeolum. Histologically, sebaceous carcinoma is a dermal-based infiltrative, nodular tumor with varying degrees of clear cell changes—well-differentiated tumors show more clear cell change as compared to more poorly differentiated variants—along with basaloid or squamous features and abundant mitotic activity (Figure 4), which may be useful in distinguishing it from the other entities in the clear cell neoplasm differential.^19-22

The Diagnosis: Metastatic Clear Cell Renal Cell Carcinoma

Renal cell carcinoma (RCC) is a common genitourinary system malignancy with incidence peaking between 50 and 70 years of age and a male predominance.¹ The clear cell variant is the most common subtype of RCC, accounting for 70% to 75% of all cases. It is known to be a highly aggressive malignancy that frequently metastasizes to the lungs, lymphatics, bones, liver, and brain.^2,3 Approximately 20% to 50% of patients with RCC eventually will develop metastasis after nephrectomy.⁴ Survival with metastatic RCC to any site typically is in the range of 10 to 22 months.^5,6 Cutaneous metastases of RCC rarely have been reported in the literature (3%–6% of cases⁷) and most commonly are found on the scalp, followed by the chest or abdomen. ⁸ Cutaneous metastases generally are regarded as a late manifestation of the disease with a very poor prognosis. ⁹ It is unusual to identify cutaneous RCC metastasis without known RCC or other symptoms consistent with advanced RCC, such as hematuria or abdominal/flank pain. Renal cell carcinoma accounts for an estimated 6% to 7% of all cutaneous metastatic lesions.¹⁰ Cutaneous metastatic lesions of RCC often are solitary and grow rapidly, with the clinical appearance of an erythematous or violaceous, nodular, highly vascular, and often hemorrhagic growth.^9,11,12

Following the histologic diagnosis of metastatic clear cell RCC, our patient was referred to medical oncology for further workup. Magnetic resonance imaging and a positron emission tomography scan demonstrated widespread disease with a 7-cm left renal mass, liver and lung metastases, and bilateral mediastinal lymphadenopathy. The patient was started on combination immunotherapy as a palliative treatment given the widespread disease.

Histologically, clear cell RCC is characterized by lipid and glycogen-rich cells with ample cytoplasm and a well-developed vascular network, which often is thin walled with a chicken wire–like architecture. Metastatic clear cell RCC tumor cells may form glandular, acinar, or papillary structures with variable lymphocytic inflammatory infiltrates and abundant capillary formation. Immunohistochemically, the tumor cells should demonstrate positivity for paired box gene 8, PAX8, and RCC marker antigen.¹³ Vimentin and carcinoembryonic antigen may be utilized to distinguish from hidradenoma as carcinoembryonic antigen will be positive in hidradenoma and vimentin will be negative.¹⁴ Renal cell carcinoma also has a common molecular signature of von Hippel-Lindau tumor suppressor gene inactivation as well as upregulation of hypoxia inducible factor and vascular endothelial growth factor.¹⁵

Balloon cell nevi often clinically present in young patients as bicolored nevi that sometimes are polypoid or verrucous in appearance with central yellow globules surrounded by a peripheral reticular pattern on dermoscopy. Histologically, balloon cell nevi are characterized by large cells with small, round, centrally located basophilic nuclei and clear foamy cytoplasm (Figure 1), which are thought to be formed by progressive vacuolization of melanocytes due to the enlargement and disintegration of melanosomes. This ballooning change reflects an seen in malignant melanoma, in which case nuclear pleomorphism, atypia, and increased mitotic activity also are observed. The prominent vascular network characteristic of RCC typically is not present.¹⁶

Clear cell hidradenomas are benign skin appendage tumors that often present as small, firm, solitary dermal nodules that may extend into the subcutaneous fat. They have a predilection for the head, face, and arms and demonstrate 2 predominant cell types, including a polyhedral cell with a rounded nucleus and slightly basophilic cytoplasm as well as a round cell with clear cytoplasm and bland nuclei (Figure 2). The latter cell type is less common, representing the predominant cell type in less than one-third of hidradenomas, and can present a diagnostic quandary based on histologic similarity to other clear cell neoplasms. The clear cells contain glycogen but no lipid. Ductlike structures often are present, and the intervening stroma varies from delicate vascularized cords of fibrous tissue to dense hyalinized collagen. Immunohistochemistry may be required for definitive diagnosis, and clear cell hidradenomas should react with monoclonal antibodies that label both eccrine and apocrine secretory elements, such as cytokeratins 6/18, 7, and 8/18.¹⁷

Pyogenic granulomas (also referred to as lobular capillary hemangiomas) are common and present clinically as rapidly growing, polypoid, red masses surrounded by a thickened epidermis that often are found on the fingers or lips. This entity is benign and often regresses spontaneously. Histologically, pyogenic granulomas are characterized by a lobular pattern of vascular proliferation associated with edema and inflammation resembling granulation tissue, with acanthosis and hyperkeratosis at the edges of the lesion (Figure 3).¹⁸

Sebaceous carcinoma is a locally aggressive malignant neoplasm arising from the cells of the sebaceous glands and occurring most commonly in the periorbital area. This neoplasm most often affects older adults, with a mean age at diagnosis of 63 to 77 years. It commonly presents as a solitary nodule with yellowish discoloration and madarosis, which is a key distinguishing feature to differentiate this entity from a chalazion or hordeolum. Histologically, sebaceous carcinoma is a dermal-based infiltrative, nodular tumor with varying degrees of clear cell changes—well-differentiated tumors show more clear cell change as compared to more poorly differentiated variants—along with basaloid or squamous features and abundant mitotic activity (Figure 4), which may be useful in distinguishing it from the other entities in the clear cell neoplasm differential.^19-22

The Diagnosis: Metastatic Clear Cell Renal Cell Carcinoma

Renal cell carcinoma (RCC) is a common genitourinary system malignancy with incidence peaking between 50 and 70 years of age and a male predominance.¹ The clear cell variant is the most common subtype of RCC, accounting for 70% to 75% of all cases. It is known to be a highly aggressive malignancy that frequently metastasizes to the lungs, lymphatics, bones, liver, and brain.^2,3 Approximately 20% to 50% of patients with RCC eventually will develop metastasis after nephrectomy.⁴ Survival with metastatic RCC to any site typically is in the range of 10 to 22 months.^5,6 Cutaneous metastases of RCC rarely have been reported in the literature (3%–6% of cases⁷) and most commonly are found on the scalp, followed by the chest or abdomen. ⁸ Cutaneous metastases generally are regarded as a late manifestation of the disease with a very poor prognosis. ⁹ It is unusual to identify cutaneous RCC metastasis without known RCC or other symptoms consistent with advanced RCC, such as hematuria or abdominal/flank pain. Renal cell carcinoma accounts for an estimated 6% to 7% of all cutaneous metastatic lesions.¹⁰ Cutaneous metastatic lesions of RCC often are solitary and grow rapidly, with the clinical appearance of an erythematous or violaceous, nodular, highly vascular, and often hemorrhagic growth.^9,11,12

Following the histologic diagnosis of metastatic clear cell RCC, our patient was referred to medical oncology for further workup. Magnetic resonance imaging and a positron emission tomography scan demonstrated widespread disease with a 7-cm left renal mass, liver and lung metastases, and bilateral mediastinal lymphadenopathy. The patient was started on combination immunotherapy as a palliative treatment given the widespread disease.

Histologically, clear cell RCC is characterized by lipid and glycogen-rich cells with ample cytoplasm and a well-developed vascular network, which often is thin walled with a chicken wire–like architecture. Metastatic clear cell RCC tumor cells may form glandular, acinar, or papillary structures with variable lymphocytic inflammatory infiltrates and abundant capillary formation. Immunohistochemically, the tumor cells should demonstrate positivity for paired box gene 8, PAX8, and RCC marker antigen.¹³ Vimentin and carcinoembryonic antigen may be utilized to distinguish from hidradenoma as carcinoembryonic antigen will be positive in hidradenoma and vimentin will be negative.¹⁴ Renal cell carcinoma also has a common molecular signature of von Hippel-Lindau tumor suppressor gene inactivation as well as upregulation of hypoxia inducible factor and vascular endothelial growth factor.¹⁵

Balloon cell nevi often clinically present in young patients as bicolored nevi that sometimes are polypoid or verrucous in appearance with central yellow globules surrounded by a peripheral reticular pattern on dermoscopy. Histologically, balloon cell nevi are characterized by large cells with small, round, centrally located basophilic nuclei and clear foamy cytoplasm (Figure 1), which are thought to be formed by progressive vacuolization of melanocytes due to the enlargement and disintegration of melanosomes. This ballooning change reflects an seen in malignant melanoma, in which case nuclear pleomorphism, atypia, and increased mitotic activity also are observed. The prominent vascular network characteristic of RCC typically is not present.¹⁶

Clear cell hidradenomas are benign skin appendage tumors that often present as small, firm, solitary dermal nodules that may extend into the subcutaneous fat. They have a predilection for the head, face, and arms and demonstrate 2 predominant cell types, including a polyhedral cell with a rounded nucleus and slightly basophilic cytoplasm as well as a round cell with clear cytoplasm and bland nuclei (Figure 2). The latter cell type is less common, representing the predominant cell type in less than one-third of hidradenomas, and can present a diagnostic quandary based on histologic similarity to other clear cell neoplasms. The clear cells contain glycogen but no lipid. Ductlike structures often are present, and the intervening stroma varies from delicate vascularized cords of fibrous tissue to dense hyalinized collagen. Immunohistochemistry may be required for definitive diagnosis, and clear cell hidradenomas should react with monoclonal antibodies that label both eccrine and apocrine secretory elements, such as cytokeratins 6/18, 7, and 8/18.¹⁷

Pyogenic granulomas (also referred to as lobular capillary hemangiomas) are common and present clinically as rapidly growing, polypoid, red masses surrounded by a thickened epidermis that often are found on the fingers or lips. This entity is benign and often regresses spontaneously. Histologically, pyogenic granulomas are characterized by a lobular pattern of vascular proliferation associated with edema and inflammation resembling granulation tissue, with acanthosis and hyperkeratosis at the edges of the lesion (Figure 3).¹⁸

Sebaceous carcinoma is a locally aggressive malignant neoplasm arising from the cells of the sebaceous glands and occurring most commonly in the periorbital area. This neoplasm most often affects older adults, with a mean age at diagnosis of 63 to 77 years. It commonly presents as a solitary nodule with yellowish discoloration and madarosis, which is a key distinguishing feature to differentiate this entity from a chalazion or hordeolum. Histologically, sebaceous carcinoma is a dermal-based infiltrative, nodular tumor with varying degrees of clear cell changes—well-differentiated tumors show more clear cell change as compared to more poorly differentiated variants—along with basaloid or squamous features and abundant mitotic activity (Figure 4), which may be useful in distinguishing it from the other entities in the clear cell neoplasm differential.^19-22

The Diagnosis: Lupus Erythematosus Tumidus

Histopathologic evaluation of a punch biopsy revealed focal dermal mucin deposition and CD123+ discrete clusters of plasmacytoid dendritic cells without interface changes (Figure 1), favoring a diagnosis of lupus erythematosus tumidus (LET) in our patient. There was no clinical improvement in symptoms when she previously was treated with topical antifungals or class III corticosteroid creams. Tacrolimus ointment 0.1% twice daily for 1 month did not result in substantial improvement in the appearance of the plaque, and it spontaneously resolved after 2 to 3 months. She declined treatment with hydroxychloroquine.

Lupus erythematosus tumidus is an uncommon subtype of chronic cutaneous lupus erythematosus with no distinct etiology. It is clinically characterized by edematous, urticarial, single or multiple plaques with a smooth surface affecting sun-exposed areas that can last for months to years.¹ In contrast to other variations of chronic cutaneous lupus such as discoid lupus erythematosus, LET lesions lack surface papulosquamous features such as scaling, atrophy, and follicular plugging.^1-4 Based solely on histologic findings, LET may be indistinguishable from reticular erythematous mucinosis and Jessner lymphocytic infiltration of the skin (JLIS) due to a similar lack of epidermal involvement and presence of a perivascular lymphocytic infiltrate (Figure 2).

The average age at disease onset is 36 years, nearly the same as that described in discoid lupus erythematosus.⁴ Lupus erythematosus tumidus has a favorable prognosis and commonly presents without other autoimmune signs, serologic abnormalities, or gender preference, with concomitant systemic lupus erythematosus sometimes reported.⁵

The absence of clinical and histological epidermal involvement are the most important clues to aid in the diagnosis. It has been postulated that JLIS could be an early cutaneous manifestation of LET.⁶ The differential diagnosis also may include erythema annulare centrifugum, granuloma annulare, and urticarial vasculitis. Lesions typically respond well to photoprotection, topical corticosteroids, and/or antimalarials. The addition of tacrolimus ointment 0.1% may result in complete regression without recurrence.⁷

Erythema annulare centrifugum is a reactive erythema that classically begins as a pink papule that gradually enlarges to form an annular erythematous plaque with a fine trailing scale that may recur.⁸ The histopathology of erythema annulare centrifugum shares features seen in LET, making the diagnosis difficult; however, secondary changes to the epidermis (eg, spongiosis, hyperkeratosis) may be seen. This condition has been associated with lymphoproliferative malignancies.⁸

Reticular erythematous mucinosis is clinically distinguished from LET, as it presents as reticular, rather than arciform, erythematous macules, papules, or plaques that may be asymptomatic or pruritic.⁹ Histopathology typically shows more superficial mucin deposition than in LET as well as superficial to mid-dermal perivascular and periadnexal lymphocytic infiltrates. Reticular erythematous mucinosis more frequently is reported in women in their 30s and 40s and has been associated with UV exposure and hormonal triggers, such as oral contraceptive medications and pregnancy.⁹

Granuloma annulare typically presents as asymptomatic, erythematous, annular plaques or papules in young women.¹⁰ There are several histologic subtypes that show focal collagen degeneration, inflammation with palisaded or interstitial histiocytes, and mucin deposition, regardless of clinical presentation. Granuloma annulare has been associated with systemic diseases including type 2 diabetes mellitus and thyroid disease. Localized granuloma annulare most commonly presents on the dorsal aspects of the hands or feet.¹⁰

We present a case of LET on the face. Although histologically similar to other dermatoses, LET often lacks epidermal involvement and presents on sun-exposed areas of the body. Jessner lymphocytic infiltration of the skin also should be considered in the differential, as there is an overlap of clinical and histopathological features; JLIS lacks mucin deposits.⁶ This case reinforces the importance of correlating clinical with histopathologic findings. Our patient was treated with tacrolimus ointment 0.1%, and the plaque eventually resolved in 2 to 3 months without recurrence. This condition should be included in the differential diagnosis of recurring annular plaques on sunexposed areas, particularly in middle-aged adults, even in the absence of systemic involvement.

The Diagnosis: Lupus Erythematosus Tumidus

Histopathologic evaluation of a punch biopsy revealed focal dermal mucin deposition and CD123+ discrete clusters of plasmacytoid dendritic cells without interface changes (Figure 1), favoring a diagnosis of lupus erythematosus tumidus (LET) in our patient. There was no clinical improvement in symptoms when she previously was treated with topical antifungals or class III corticosteroid creams. Tacrolimus ointment 0.1% twice daily for 1 month did not result in substantial improvement in the appearance of the plaque, and it spontaneously resolved after 2 to 3 months. She declined treatment with hydroxychloroquine.

Lupus erythematosus tumidus is an uncommon subtype of chronic cutaneous lupus erythematosus with no distinct etiology. It is clinically characterized by edematous, urticarial, single or multiple plaques with a smooth surface affecting sun-exposed areas that can last for months to years.¹ In contrast to other variations of chronic cutaneous lupus such as discoid lupus erythematosus, LET lesions lack surface papulosquamous features such as scaling, atrophy, and follicular plugging.^1-4 Based solely on histologic findings, LET may be indistinguishable from reticular erythematous mucinosis and Jessner lymphocytic infiltration of the skin (JLIS) due to a similar lack of epidermal involvement and presence of a perivascular lymphocytic infiltrate (Figure 2).

The average age at disease onset is 36 years, nearly the same as that described in discoid lupus erythematosus.⁴ Lupus erythematosus tumidus has a favorable prognosis and commonly presents without other autoimmune signs, serologic abnormalities, or gender preference, with concomitant systemic lupus erythematosus sometimes reported.⁵

The absence of clinical and histological epidermal involvement are the most important clues to aid in the diagnosis. It has been postulated that JLIS could be an early cutaneous manifestation of LET.⁶ The differential diagnosis also may include erythema annulare centrifugum, granuloma annulare, and urticarial vasculitis. Lesions typically respond well to photoprotection, topical corticosteroids, and/or antimalarials. The addition of tacrolimus ointment 0.1% may result in complete regression without recurrence.⁷

Erythema annulare centrifugum is a reactive erythema that classically begins as a pink papule that gradually enlarges to form an annular erythematous plaque with a fine trailing scale that may recur.⁸ The histopathology of erythema annulare centrifugum shares features seen in LET, making the diagnosis difficult; however, secondary changes to the epidermis (eg, spongiosis, hyperkeratosis) may be seen. This condition has been associated with lymphoproliferative malignancies.⁸

Reticular erythematous mucinosis is clinically distinguished from LET, as it presents as reticular, rather than arciform, erythematous macules, papules, or plaques that may be asymptomatic or pruritic.⁹ Histopathology typically shows more superficial mucin deposition than in LET as well as superficial to mid-dermal perivascular and periadnexal lymphocytic infiltrates. Reticular erythematous mucinosis more frequently is reported in women in their 30s and 40s and has been associated with UV exposure and hormonal triggers, such as oral contraceptive medications and pregnancy.⁹

Granuloma annulare typically presents as asymptomatic, erythematous, annular plaques or papules in young women.¹⁰ There are several histologic subtypes that show focal collagen degeneration, inflammation with palisaded or interstitial histiocytes, and mucin deposition, regardless of clinical presentation. Granuloma annulare has been associated with systemic diseases including type 2 diabetes mellitus and thyroid disease. Localized granuloma annulare most commonly presents on the dorsal aspects of the hands or feet.¹⁰

We present a case of LET on the face. Although histologically similar to other dermatoses, LET often lacks epidermal involvement and presents on sun-exposed areas of the body. Jessner lymphocytic infiltration of the skin also should be considered in the differential, as there is an overlap of clinical and histopathological features; JLIS lacks mucin deposits.⁶ This case reinforces the importance of correlating clinical with histopathologic findings. Our patient was treated with tacrolimus ointment 0.1%, and the plaque eventually resolved in 2 to 3 months without recurrence. This condition should be included in the differential diagnosis of recurring annular plaques on sunexposed areas, particularly in middle-aged adults, even in the absence of systemic involvement.

The Diagnosis: Lupus Erythematosus Tumidus

Histopathologic evaluation of a punch biopsy revealed focal dermal mucin deposition and CD123+ discrete clusters of plasmacytoid dendritic cells without interface changes (Figure 1), favoring a diagnosis of lupus erythematosus tumidus (LET) in our patient. There was no clinical improvement in symptoms when she previously was treated with topical antifungals or class III corticosteroid creams. Tacrolimus ointment 0.1% twice daily for 1 month did not result in substantial improvement in the appearance of the plaque, and it spontaneously resolved after 2 to 3 months. She declined treatment with hydroxychloroquine.

Lupus erythematosus tumidus is an uncommon subtype of chronic cutaneous lupus erythematosus with no distinct etiology. It is clinically characterized by edematous, urticarial, single or multiple plaques with a smooth surface affecting sun-exposed areas that can last for months to years.¹ In contrast to other variations of chronic cutaneous lupus such as discoid lupus erythematosus, LET lesions lack surface papulosquamous features such as scaling, atrophy, and follicular plugging.^1-4 Based solely on histologic findings, LET may be indistinguishable from reticular erythematous mucinosis and Jessner lymphocytic infiltration of the skin (JLIS) due to a similar lack of epidermal involvement and presence of a perivascular lymphocytic infiltrate (Figure 2).

The average age at disease onset is 36 years, nearly the same as that described in discoid lupus erythematosus.⁴ Lupus erythematosus tumidus has a favorable prognosis and commonly presents without other autoimmune signs, serologic abnormalities, or gender preference, with concomitant systemic lupus erythematosus sometimes reported.⁵

The absence of clinical and histological epidermal involvement are the most important clues to aid in the diagnosis. It has been postulated that JLIS could be an early cutaneous manifestation of LET.⁶ The differential diagnosis also may include erythema annulare centrifugum, granuloma annulare, and urticarial vasculitis. Lesions typically respond well to photoprotection, topical corticosteroids, and/or antimalarials. The addition of tacrolimus ointment 0.1% may result in complete regression without recurrence.⁷

Erythema annulare centrifugum is a reactive erythema that classically begins as a pink papule that gradually enlarges to form an annular erythematous plaque with a fine trailing scale that may recur.⁸ The histopathology of erythema annulare centrifugum shares features seen in LET, making the diagnosis difficult; however, secondary changes to the epidermis (eg, spongiosis, hyperkeratosis) may be seen. This condition has been associated with lymphoproliferative malignancies.⁸

Reticular erythematous mucinosis is clinically distinguished from LET, as it presents as reticular, rather than arciform, erythematous macules, papules, or plaques that may be asymptomatic or pruritic.⁹ Histopathology typically shows more superficial mucin deposition than in LET as well as superficial to mid-dermal perivascular and periadnexal lymphocytic infiltrates. Reticular erythematous mucinosis more frequently is reported in women in their 30s and 40s and has been associated with UV exposure and hormonal triggers, such as oral contraceptive medications and pregnancy.⁹

Granuloma annulare typically presents as asymptomatic, erythematous, annular plaques or papules in young women.¹⁰ There are several histologic subtypes that show focal collagen degeneration, inflammation with palisaded or interstitial histiocytes, and mucin deposition, regardless of clinical presentation. Granuloma annulare has been associated with systemic diseases including type 2 diabetes mellitus and thyroid disease. Localized granuloma annulare most commonly presents on the dorsal aspects of the hands or feet.¹⁰

We present a case of LET on the face. Although histologically similar to other dermatoses, LET often lacks epidermal involvement and presents on sun-exposed areas of the body. Jessner lymphocytic infiltration of the skin also should be considered in the differential, as there is an overlap of clinical and histopathological features; JLIS lacks mucin deposits.⁶ This case reinforces the importance of correlating clinical with histopathologic findings. Our patient was treated with tacrolimus ointment 0.1%, and the plaque eventually resolved in 2 to 3 months without recurrence. This condition should be included in the differential diagnosis of recurring annular plaques on sunexposed areas, particularly in middle-aged adults, even in the absence of systemic involvement.

Primary cutaneous marginal zone lymphoma (PCMZL) is a form of cutaneous lymphoma that typically remains indolent and is limited to the skin. Recurrences may occur. Rarely, lymph nodes, the gastrointestinal system, lung, bone and bone marrow may be involved as extracutaneous sites.

Primary cutaneous B-cell lymphomas account for approximately 25% of all cutaneous lymphomas. Clinically, patients present with either solitary or multiple papules or plaques, typically on the upper extremities or trunk.

Histopathology is vital for the correct diagnosis. In this patient, the histologic report was written as follows: “The findings are those of a well-differentiated but atypical diffuse mixed small lymphocytic infiltrate representing a mixture of T-cells and B-cells. The minor component of the infiltrate is of T-cell lineage, whereby the cells do not show any phenotypic abnormalities. The background cell population is interpreted as reactive. However, the dominant cell population is in fact of B-cell lineage. It is extensively highlighted by CD20. Only a minor component of the B cell infiltrate appeared to be in the context of representing germinal centers as characterized by small foci of centrocytic and centroblastic infiltration highlighted by BCL6 and CD10. The overwhelming B-cell component is a non–germinal center small B cell that does demonstrate BCL2 positivity and significant immunoreactivity for CD23. This small lymphocytic infiltrate obscures the germinal centers. There are only a few plasma cells; they do not show light chain restriction.”

The pathologist remarked that “this type of morphology of a diffuse small B-cell lymphocytic infiltrate that is without any evidence of light chain restriction amidst plasma cells, whereby the B cell component is dominant over the T-cell component would in fact be consistent with a unique variant of marginal zone lymphoma derived from a naive mantle zone.”

PCMZL has an excellent prognosis. When limited to the skin, local radiation or excision are effective treatments. Intravenous rituximab has been used to treat multifocal PCMZL. This patient was found to have no extracutaneous involvement and was treated with radiation.

This case and photo were submitted by Dr. Bilu Martin.

Dr. Bilu Martin is a board-certified dermatologist in private practice at Premier Dermatology, MD, in Aventura, Fla. More diagnostic cases are available at mdedge.com/dermatology. To submit a case for possible publication, send an email to [email protected].

References

Virmani P et al. JAAD Case Rep. 2017 Jun 14;3(4):269-72.

Magro CM and Olson LC. Ann Diagn Pathol. 2018 Jun;34:116-21.

Primary cutaneous marginal zone lymphoma (PCMZL) is a form of cutaneous lymphoma that typically remains indolent and is limited to the skin. Recurrences may occur. Rarely, lymph nodes, the gastrointestinal system, lung, bone and bone marrow may be involved as extracutaneous sites.

Primary cutaneous B-cell lymphomas account for approximately 25% of all cutaneous lymphomas. Clinically, patients present with either solitary or multiple papules or plaques, typically on the upper extremities or trunk.

Histopathology is vital for the correct diagnosis. In this patient, the histologic report was written as follows: “The findings are those of a well-differentiated but atypical diffuse mixed small lymphocytic infiltrate representing a mixture of T-cells and B-cells. The minor component of the infiltrate is of T-cell lineage, whereby the cells do not show any phenotypic abnormalities. The background cell population is interpreted as reactive. However, the dominant cell population is in fact of B-cell lineage. It is extensively highlighted by CD20. Only a minor component of the B cell infiltrate appeared to be in the context of representing germinal centers as characterized by small foci of centrocytic and centroblastic infiltration highlighted by BCL6 and CD10. The overwhelming B-cell component is a non–germinal center small B cell that does demonstrate BCL2 positivity and significant immunoreactivity for CD23. This small lymphocytic infiltrate obscures the germinal centers. There are only a few plasma cells; they do not show light chain restriction.”

The pathologist remarked that “this type of morphology of a diffuse small B-cell lymphocytic infiltrate that is without any evidence of light chain restriction amidst plasma cells, whereby the B cell component is dominant over the T-cell component would in fact be consistent with a unique variant of marginal zone lymphoma derived from a naive mantle zone.”

PCMZL has an excellent prognosis. When limited to the skin, local radiation or excision are effective treatments. Intravenous rituximab has been used to treat multifocal PCMZL. This patient was found to have no extracutaneous involvement and was treated with radiation.

This case and photo were submitted by Dr. Bilu Martin.

Dr. Bilu Martin is a board-certified dermatologist in private practice at Premier Dermatology, MD, in Aventura, Fla. More diagnostic cases are available at mdedge.com/dermatology. To submit a case for possible publication, send an email to [email protected].

References

Virmani P et al. JAAD Case Rep. 2017 Jun 14;3(4):269-72.

Magro CM and Olson LC. Ann Diagn Pathol. 2018 Jun;34:116-21.

Primary cutaneous marginal zone lymphoma (PCMZL) is a form of cutaneous lymphoma that typically remains indolent and is limited to the skin. Recurrences may occur. Rarely, lymph nodes, the gastrointestinal system, lung, bone and bone marrow may be involved as extracutaneous sites.

Primary cutaneous B-cell lymphomas account for approximately 25% of all cutaneous lymphomas. Clinically, patients present with either solitary or multiple papules or plaques, typically on the upper extremities or trunk.

Histopathology is vital for the correct diagnosis. In this patient, the histologic report was written as follows: “The findings are those of a well-differentiated but atypical diffuse mixed small lymphocytic infiltrate representing a mixture of T-cells and B-cells. The minor component of the infiltrate is of T-cell lineage, whereby the cells do not show any phenotypic abnormalities. The background cell population is interpreted as reactive. However, the dominant cell population is in fact of B-cell lineage. It is extensively highlighted by CD20. Only a minor component of the B cell infiltrate appeared to be in the context of representing germinal centers as characterized by small foci of centrocytic and centroblastic infiltration highlighted by BCL6 and CD10. The overwhelming B-cell component is a non–germinal center small B cell that does demonstrate BCL2 positivity and significant immunoreactivity for CD23. This small lymphocytic infiltrate obscures the germinal centers. There are only a few plasma cells; they do not show light chain restriction.”

The pathologist remarked that “this type of morphology of a diffuse small B-cell lymphocytic infiltrate that is without any evidence of light chain restriction amidst plasma cells, whereby the B cell component is dominant over the T-cell component would in fact be consistent with a unique variant of marginal zone lymphoma derived from a naive mantle zone.”

PCMZL has an excellent prognosis. When limited to the skin, local radiation or excision are effective treatments. Intravenous rituximab has been used to treat multifocal PCMZL. This patient was found to have no extracutaneous involvement and was treated with radiation.

This case and photo were submitted by Dr. Bilu Martin.

Dr. Bilu Martin is a board-certified dermatologist in private practice at Premier Dermatology, MD, in Aventura, Fla. More diagnostic cases are available at mdedge.com/dermatology. To submit a case for possible publication, send an email to [email protected].

References

Virmani P et al. JAAD Case Rep. 2017 Jun 14;3(4):269-72.

Magro CM and Olson LC. Ann Diagn Pathol. 2018 Jun;34:116-21.

The Diagnosis: Calciphylaxis

Histopathology revealed epidermal and dermal necrosis, a perivascular neutrophilic infiltrate, and scattered microcalcifications within small- and medium-sized subcutaneous vessels, consistent with a diagnosis of calciphylaxis (Figure). Calciphylaxis (also known as calcific uremic arteriolopathy) is a rare, severe, and often fatal vasculopathy that predominately occurs in patients with end-stage renal failure.¹ The pathogenesis of calciphylaxis remains poorly understood; however, it generally is thought that an imbalance in calcium homeostasis in susceptible hosts results in the precipitation of calcium phosphate within vessel walls leading to endothelial damage with subsequent thrombotic vasculopathy and ischemic tissue damage. Acquired and congenital hypercoagulable states have been implicated in the pathogenesis of calciphylaxis.²

Treatment of calciphylaxis is directed at normalizing abnormal calcium metabolism; removing possible exacerbating agents, such as warfarin, systemic corticosteroids, calcium, and iron; and transitioning patients with end-stage renal disease to hemodialysis, if not already initiated. The treatment approach is multifaceted, and numerous therapies usually are attempted simultaneously. Vitamin K supplementation, low-calcium dialysate, non–calcium carbonate phosphate binders, cinacalcet, becaplermin, bisphosphonates, hyperbaric oxygen, and intravenous sodium thiosulfate all have been utilized with some success. Currently, intravenous sodium thiosulfate is the mainstay therapy for the treatment of calciphylaxis.² Although the mechanism of sodium thiosulfate is not entirely understood, it is known to have anticalcification, vasodilatory, and antioxidant properties.

Retiform purpura clinically is characterized by reticulated, branching, purpuric skin lesions. It occurs following vascular insult by way of vessel lumen occlusion (thrombotic vasculopathy) and less frequently by vessel wall inflammation (vasculitis). The differential diagnosis for retiform purpura includes various causes of microvascular occlusion, including hypercoagulable states and type I cryoglobulinemia, calciphylaxis, infections, autoimmune vasculitic conditions, and embolic causes.³

Cutaneous disease in individuals with antiphospholipid antibodies may present similarly with retiform purpura in the form of necrotizing livedo reticularis, leg ulcers, or widespread cutaneous necrosis. Histopathologic findings include vascular thrombi with partial or complete obstruction of the small- to medium-sized arteries at the dermoepidermal junction, often in the absence of an inflammatory infiltrate.⁴ True vasculitis is not typical of antiphospholipid syndrome.

Medium vessel vasculitides, such as polyarteritis nodosa, clinically present with livedo reticularis, subcutaneous nodules, and tissue necrosis. Dermatopathologic evaluation of a medium-sized vessel vasculitis would demonstrate a neutrophilic vasculitis involving vessels within the deep dermis and septa of subcutaneous fat.⁵ Tissue sampling should be deep and wide enough to visualize the pathology, as shallow biopsies may show intraluminal thrombi of the superficial dermal plexus only, while a narrow specimen may result in falsenegative findings due to the focal nature of vessel involvement in conditions such as polyarteritis nodosa.

Type I cryoglobulinemia often is a manifestation of plasma cell dyscrasia and commonly presents with Raynaud phenomenon, livedo reticularis, and acrocyanosis of helices⁶ ; pathology demonstrates vessel occlusion and erythrocyte extravasation. In contrast, types II and III, also known as mixed cryoglobulinemia, are associated with hepatitis C and autoimmune connective tissue disease. They clinically present as purpuric plaques and nodules that have a propensity to vesiculate and ulcerate.⁷ Histopathologically, features of leukocytoclastic vasculitis are seen, and direct immunofluorescence demonstrates perivascular granular deposits consisting predominantly of IgM and C3 in the papillary dermis.⁸

Warfarin therapy, particularly in high initial doses, can induce lesions of cutaneous necrosis, which clinically may resemble the appearance of calciphylaxis. Warfarininduced skin necrosis typically occurs 3 to 5 days after the initiation of therapy and is the result of a temporary prothrombotic state.9 The half-life of antithrombotic protein C is shorter than vitamin K–dependent prothrombotic factors II, X, and IX. Early in warfarin treatment, an acquired state of reduced protein C level exists, which can lead to vessel thrombosis and subsequent cutaneous necrosis. Treatment of warfarin-induced skin necrosis involves cessation of warfarin, supplementation with vitamin K to reverse the effects of warfarin, and the initiation of heparin or low-molecular-weight heparin.⁹

The Diagnosis: Calciphylaxis

Histopathology revealed epidermal and dermal necrosis, a perivascular neutrophilic infiltrate, and scattered microcalcifications within small- and medium-sized subcutaneous vessels, consistent with a diagnosis of calciphylaxis (Figure). Calciphylaxis (also known as calcific uremic arteriolopathy) is a rare, severe, and often fatal vasculopathy that predominately occurs in patients with end-stage renal failure.¹ The pathogenesis of calciphylaxis remains poorly understood; however, it generally is thought that an imbalance in calcium homeostasis in susceptible hosts results in the precipitation of calcium phosphate within vessel walls leading to endothelial damage with subsequent thrombotic vasculopathy and ischemic tissue damage. Acquired and congenital hypercoagulable states have been implicated in the pathogenesis of calciphylaxis.²

Treatment of calciphylaxis is directed at normalizing abnormal calcium metabolism; removing possible exacerbating agents, such as warfarin, systemic corticosteroids, calcium, and iron; and transitioning patients with end-stage renal disease to hemodialysis, if not already initiated. The treatment approach is multifaceted, and numerous therapies usually are attempted simultaneously. Vitamin K supplementation, low-calcium dialysate, non–calcium carbonate phosphate binders, cinacalcet, becaplermin, bisphosphonates, hyperbaric oxygen, and intravenous sodium thiosulfate all have been utilized with some success. Currently, intravenous sodium thiosulfate is the mainstay therapy for the treatment of calciphylaxis.² Although the mechanism of sodium thiosulfate is not entirely understood, it is known to have anticalcification, vasodilatory, and antioxidant properties.

Retiform purpura clinically is characterized by reticulated, branching, purpuric skin lesions. It occurs following vascular insult by way of vessel lumen occlusion (thrombotic vasculopathy) and less frequently by vessel wall inflammation (vasculitis). The differential diagnosis for retiform purpura includes various causes of microvascular occlusion, including hypercoagulable states and type I cryoglobulinemia, calciphylaxis, infections, autoimmune vasculitic conditions, and embolic causes.³

Cutaneous disease in individuals with antiphospholipid antibodies may present similarly with retiform purpura in the form of necrotizing livedo reticularis, leg ulcers, or widespread cutaneous necrosis. Histopathologic findings include vascular thrombi with partial or complete obstruction of the small- to medium-sized arteries at the dermoepidermal junction, often in the absence of an inflammatory infiltrate.⁴ True vasculitis is not typical of antiphospholipid syndrome.

Medium vessel vasculitides, such as polyarteritis nodosa, clinically present with livedo reticularis, subcutaneous nodules, and tissue necrosis. Dermatopathologic evaluation of a medium-sized vessel vasculitis would demonstrate a neutrophilic vasculitis involving vessels within the deep dermis and septa of subcutaneous fat.⁵ Tissue sampling should be deep and wide enough to visualize the pathology, as shallow biopsies may show intraluminal thrombi of the superficial dermal plexus only, while a narrow specimen may result in falsenegative findings due to the focal nature of vessel involvement in conditions such as polyarteritis nodosa.

Type I cryoglobulinemia often is a manifestation of plasma cell dyscrasia and commonly presents with Raynaud phenomenon, livedo reticularis, and acrocyanosis of helices⁶ ; pathology demonstrates vessel occlusion and erythrocyte extravasation. In contrast, types II and III, also known as mixed cryoglobulinemia, are associated with hepatitis C and autoimmune connective tissue disease. They clinically present as purpuric plaques and nodules that have a propensity to vesiculate and ulcerate.⁷ Histopathologically, features of leukocytoclastic vasculitis are seen, and direct immunofluorescence demonstrates perivascular granular deposits consisting predominantly of IgM and C3 in the papillary dermis.⁸

Warfarin therapy, particularly in high initial doses, can induce lesions of cutaneous necrosis, which clinically may resemble the appearance of calciphylaxis. Warfarininduced skin necrosis typically occurs 3 to 5 days after the initiation of therapy and is the result of a temporary prothrombotic state.9 The half-life of antithrombotic protein C is shorter than vitamin K–dependent prothrombotic factors II, X, and IX. Early in warfarin treatment, an acquired state of reduced protein C level exists, which can lead to vessel thrombosis and subsequent cutaneous necrosis. Treatment of warfarin-induced skin necrosis involves cessation of warfarin, supplementation with vitamin K to reverse the effects of warfarin, and the initiation of heparin or low-molecular-weight heparin.⁹

The Diagnosis: Calciphylaxis

Histopathology revealed epidermal and dermal necrosis, a perivascular neutrophilic infiltrate, and scattered microcalcifications within small- and medium-sized subcutaneous vessels, consistent with a diagnosis of calciphylaxis (Figure). Calciphylaxis (also known as calcific uremic arteriolopathy) is a rare, severe, and often fatal vasculopathy that predominately occurs in patients with end-stage renal failure.¹ The pathogenesis of calciphylaxis remains poorly understood; however, it generally is thought that an imbalance in calcium homeostasis in susceptible hosts results in the precipitation of calcium phosphate within vessel walls leading to endothelial damage with subsequent thrombotic vasculopathy and ischemic tissue damage. Acquired and congenital hypercoagulable states have been implicated in the pathogenesis of calciphylaxis.²

Treatment of calciphylaxis is directed at normalizing abnormal calcium metabolism; removing possible exacerbating agents, such as warfarin, systemic corticosteroids, calcium, and iron; and transitioning patients with end-stage renal disease to hemodialysis, if not already initiated. The treatment approach is multifaceted, and numerous therapies usually are attempted simultaneously. Vitamin K supplementation, low-calcium dialysate, non–calcium carbonate phosphate binders, cinacalcet, becaplermin, bisphosphonates, hyperbaric oxygen, and intravenous sodium thiosulfate all have been utilized with some success. Currently, intravenous sodium thiosulfate is the mainstay therapy for the treatment of calciphylaxis.² Although the mechanism of sodium thiosulfate is not entirely understood, it is known to have anticalcification, vasodilatory, and antioxidant properties.

Retiform purpura clinically is characterized by reticulated, branching, purpuric skin lesions. It occurs following vascular insult by way of vessel lumen occlusion (thrombotic vasculopathy) and less frequently by vessel wall inflammation (vasculitis). The differential diagnosis for retiform purpura includes various causes of microvascular occlusion, including hypercoagulable states and type I cryoglobulinemia, calciphylaxis, infections, autoimmune vasculitic conditions, and embolic causes.³

Cutaneous disease in individuals with antiphospholipid antibodies may present similarly with retiform purpura in the form of necrotizing livedo reticularis, leg ulcers, or widespread cutaneous necrosis. Histopathologic findings include vascular thrombi with partial or complete obstruction of the small- to medium-sized arteries at the dermoepidermal junction, often in the absence of an inflammatory infiltrate.⁴ True vasculitis is not typical of antiphospholipid syndrome.

Medium vessel vasculitides, such as polyarteritis nodosa, clinically present with livedo reticularis, subcutaneous nodules, and tissue necrosis. Dermatopathologic evaluation of a medium-sized vessel vasculitis would demonstrate a neutrophilic vasculitis involving vessels within the deep dermis and septa of subcutaneous fat.⁵ Tissue sampling should be deep and wide enough to visualize the pathology, as shallow biopsies may show intraluminal thrombi of the superficial dermal plexus only, while a narrow specimen may result in falsenegative findings due to the focal nature of vessel involvement in conditions such as polyarteritis nodosa.

Type I cryoglobulinemia often is a manifestation of plasma cell dyscrasia and commonly presents with Raynaud phenomenon, livedo reticularis, and acrocyanosis of helices⁶ ; pathology demonstrates vessel occlusion and erythrocyte extravasation. In contrast, types II and III, also known as mixed cryoglobulinemia, are associated with hepatitis C and autoimmune connective tissue disease. They clinically present as purpuric plaques and nodules that have a propensity to vesiculate and ulcerate.⁷ Histopathologically, features of leukocytoclastic vasculitis are seen, and direct immunofluorescence demonstrates perivascular granular deposits consisting predominantly of IgM and C3 in the papillary dermis.⁸

Warfarin therapy, particularly in high initial doses, can induce lesions of cutaneous necrosis, which clinically may resemble the appearance of calciphylaxis. Warfarininduced skin necrosis typically occurs 3 to 5 days after the initiation of therapy and is the result of a temporary prothrombotic state.9 The half-life of antithrombotic protein C is shorter than vitamin K–dependent prothrombotic factors II, X, and IX. Early in warfarin treatment, an acquired state of reduced protein C level exists, which can lead to vessel thrombosis and subsequent cutaneous necrosis. Treatment of warfarin-induced skin necrosis involves cessation of warfarin, supplementation with vitamin K to reverse the effects of warfarin, and the initiation of heparin or low-molecular-weight heparin.⁹

Melanomas have been designated as small melanomas or micromelanomas according to their long-axis diameter (<6 mm and ≤3 mm, respectively).^1-3 Because small-diameter melanomas also have the potential to metastasize, particularly if nodular, early diagnosis can be highly rewarding. Deep melanomas with small diameters may have the same potential for metastasis as large-diameter melanomas. In this context, dermoscopy, digital dermoscopic monitoring, and total-body photography are useful in clinical practice. However, these techniques are of limited utility for small, dermoscopic feature–poor melanomas. Conversely, less than 10% of changing lesions, which are spotted via digital dermoscopic surveillance, turn out to be melanomas; therefore, simply removing all changing lesions may result in many unnecessary excisions of benign lesions.⁴

In vivo reflectance confocal microscopy (RCM) is an advanced technique that allows recognition of the architectural and cellular details of pigmented lesions. Reflectance confocal microscopy has the potential to reduce the rate of unnecessary excisions and to diminish the risk for missing a melanoma.^5-7 In meta-analyses, RCM sensitivity was reported as 90% to 93% and specificity was reported as 78% to 82% in detecting melanoma.^8,9

We describe a case that highlights the potential role of RCM in the diagnosis of small-diameter melanomas.

Case Report

A 57-year-old man with Fitzpatrick skin type III presented to the dermato-oncology unit for evaluation of multiple nevi. He was otherwise healthy and denied a history of skin cancer. Total-body skin examination with dermoscopy was performed, and several mildly atypical lesions were identified. We decided to perform digital dermoscopic monitoring. The patient’s 6-month monitoring appointment had been scheduled, but he did not arrive for the follow-up visit until 10 months after the initial examination. A lesion on the left arm, which initially was 1.5 mm in diameter, had enlarged. It was now a dark brown–gray papule with a 2.5-mm diameter (Figure 1). Dermoscopy revealed grayish globules/dots at the center of the lesion, reticular gray-blue areas, and few milialike cysts; at the periphery, a narrow rim of brownish delicate pigment network also was seen (Figure 2). The clinical and dermoscopic differential diagnosis was either an atypical nevus or an early melanoma. For a more precise diagnosis before excision, the lesion was evaluated with RCM, which takes 10 to 15 minutes to perform.

Under RCM at the epidermis level, there was a cobblestone pattern that showed a focus with mild disarrangement and few small, roundish, nucleated cells (Figure 3). A mosaic image, akin to low-magnification microscopy that enables overview of the entire lesion, at the level of the dermoepidermal junction (DEJ) showed an overall irregular meshwork pattern. Higher-magnification optical sections showed marked and diffuse (extending >10% of lesion area) architectural disorder with confluent junctional nests that were irregular to bizarre in shape and uneven in size and spacing as well as edged and nonedged papillae. At the superficial dermal level, atypical bright nucleated cells (>5 cells/mm²) were observed (Figure 4). Bright dots and/or plump bright cells within papillae also were observed. These RCM findings were highly suggestive for melanoma.

Histopathology showed an asymmetric, junctional, lentiginous, and nested proliferation of atypical epithelioid melanocytes, with few melanocytes in a pagetoid spread. There were small nests of atypical epithelioid melanocytes at the superficial dermis extending to a depth of 0.3 mm. The atypical epithelioid melanocytes displayed angulated hyperchromatic nuclei with conspicuous nucleoli and dusty brown cytoplasm. There was notable inflammation and pigment incontinence at the dermis. There was no evidence of ulceration or mitosis at the dermal component. The diagnosis of a pT1a malignant melanoma was reported (Figure 5).

Comment

A small but enlarging dark gray papule with reticular gray-blue areas under dermoscopy in a 57-year-old man is obviously suspicious for melanoma. In daily practice, this type of small-diameter melanoma is difficult to diagnose with high confidence. We balance our aim to diagnose melanomas early with the need to reduce unnecessary excisions. Reflectance confocal microscopy may allow the clinician to arrive at the correct diagnosis and management decision with confidence before excision of the lesion.

The distinction of a small-diameter melanoma from a nevus via RCM relies on evaluation of the architectural and cellular features. Findings on RCM in small-diameter melanomas have been scarcely reported in the literature; Pupelli et al¹⁰ evaluated small melanomas with a diameter of 2 to 5 mm. Among these small-diameter melanomas, the RCM features suggestive for melanomas were the presence of cytologic atypia with cellular pleomorphism, architectural disorder with irregular nests, at least 5 pagetoid cells/mm², dendrites or tangled lines (ie, short fine lines with no visible nucleus interlacing with the adjacent keratinocytes) within the epidermis, and atypical roundish cells at the DEJ.¹⁰

The distinction between an atypical nevus and a small-diameter melanoma using RCM occasionally may be challenging.¹¹ Pellacani et al¹² reported an algorithm to distinguish melanoma from atypical nevi. According to this algorithm, when at least 1 of the architectural atypia features (irregular junctional nests, short interconnections between junctional nests, and nonhomogeneous cellularity within junctional nests) and at least 1 of the cytologic atypia features (round pagetoid cells or atypical cells at the DEJ) are observed simultaneously, the lesion is diagnosed as a dysplastic nevus or a melanoma in the first step. In the second step, the RCM diagnosis of melanoma requires at least 1 of 3 parameters: roundish pagetoid cells encompassing at least 50% of the lesional area at the spinous layer, atypical cells involving at least 50% of the lesional area at the DEJ level, and nonedged papillae involving at least 10% of the lesional area.¹² Accordingly, our case corresponded with these RCM criteria for a melanoma, given that there were irregular junctional nests, atypical cells at the DEJ, and nonedged papillae involving at least 10% of the lesion.

The current limitations of RCM are the high cost of the device (approximately $58,125–$139,400 for different models), the amount of time needed to train staff in RCM units (seminars, congresses, and special courses organized by the International Confocal Working Group), and the amount of time needed for evaluation of individual lesions (15–20 minutes). However, RCM can be valuable in the clinical diagnosis of difficult lesions, as seen in our case.

Conclusion

Our case highlights the benefit of RCM in allowing the confident diagnosis and correct management of a small-diameter melanoma that turned out to be a melanoma with 0.3-mm Breslow thickness. Even so, histopathologic evaluation remains the gold standard for the diagnosis of melanoma.

Melanomas have been designated as small melanomas or micromelanomas according to their long-axis diameter (<6 mm and ≤3 mm, respectively).^1-3 Because small-diameter melanomas also have the potential to metastasize, particularly if nodular, early diagnosis can be highly rewarding. Deep melanomas with small diameters may have the same potential for metastasis as large-diameter melanomas. In this context, dermoscopy, digital dermoscopic monitoring, and total-body photography are useful in clinical practice. However, these techniques are of limited utility for small, dermoscopic feature–poor melanomas. Conversely, less than 10% of changing lesions, which are spotted via digital dermoscopic surveillance, turn out to be melanomas; therefore, simply removing all changing lesions may result in many unnecessary excisions of benign lesions.⁴

In vivo reflectance confocal microscopy (RCM) is an advanced technique that allows recognition of the architectural and cellular details of pigmented lesions. Reflectance confocal microscopy has the potential to reduce the rate of unnecessary excisions and to diminish the risk for missing a melanoma.^5-7 In meta-analyses, RCM sensitivity was reported as 90% to 93% and specificity was reported as 78% to 82% in detecting melanoma.^8,9

We describe a case that highlights the potential role of RCM in the diagnosis of small-diameter melanomas.

Case Report

A 57-year-old man with Fitzpatrick skin type III presented to the dermato-oncology unit for evaluation of multiple nevi. He was otherwise healthy and denied a history of skin cancer. Total-body skin examination with dermoscopy was performed, and several mildly atypical lesions were identified. We decided to perform digital dermoscopic monitoring. The patient’s 6-month monitoring appointment had been scheduled, but he did not arrive for the follow-up visit until 10 months after the initial examination. A lesion on the left arm, which initially was 1.5 mm in diameter, had enlarged. It was now a dark brown–gray papule with a 2.5-mm diameter (Figure 1). Dermoscopy revealed grayish globules/dots at the center of the lesion, reticular gray-blue areas, and few milialike cysts; at the periphery, a narrow rim of brownish delicate pigment network also was seen (Figure 2). The clinical and dermoscopic differential diagnosis was either an atypical nevus or an early melanoma. For a more precise diagnosis before excision, the lesion was evaluated with RCM, which takes 10 to 15 minutes to perform.

Under RCM at the epidermis level, there was a cobblestone pattern that showed a focus with mild disarrangement and few small, roundish, nucleated cells (Figure 3). A mosaic image, akin to low-magnification microscopy that enables overview of the entire lesion, at the level of the dermoepidermal junction (DEJ) showed an overall irregular meshwork pattern. Higher-magnification optical sections showed marked and diffuse (extending >10% of lesion area) architectural disorder with confluent junctional nests that were irregular to bizarre in shape and uneven in size and spacing as well as edged and nonedged papillae. At the superficial dermal level, atypical bright nucleated cells (>5 cells/mm²) were observed (Figure 4). Bright dots and/or plump bright cells within papillae also were observed. These RCM findings were highly suggestive for melanoma.

Histopathology showed an asymmetric, junctional, lentiginous, and nested proliferation of atypical epithelioid melanocytes, with few melanocytes in a pagetoid spread. There were small nests of atypical epithelioid melanocytes at the superficial dermis extending to a depth of 0.3 mm. The atypical epithelioid melanocytes displayed angulated hyperchromatic nuclei with conspicuous nucleoli and dusty brown cytoplasm. There was notable inflammation and pigment incontinence at the dermis. There was no evidence of ulceration or mitosis at the dermal component. The diagnosis of a pT1a malignant melanoma was reported (Figure 5).

Comment

A small but enlarging dark gray papule with reticular gray-blue areas under dermoscopy in a 57-year-old man is obviously suspicious for melanoma. In daily practice, this type of small-diameter melanoma is difficult to diagnose with high confidence. We balance our aim to diagnose melanomas early with the need to reduce unnecessary excisions. Reflectance confocal microscopy may allow the clinician to arrive at the correct diagnosis and management decision with confidence before excision of the lesion.

The distinction of a small-diameter melanoma from a nevus via RCM relies on evaluation of the architectural and cellular features. Findings on RCM in small-diameter melanomas have been scarcely reported in the literature; Pupelli et al¹⁰ evaluated small melanomas with a diameter of 2 to 5 mm. Among these small-diameter melanomas, the RCM features suggestive for melanomas were the presence of cytologic atypia with cellular pleomorphism, architectural disorder with irregular nests, at least 5 pagetoid cells/mm², dendrites or tangled lines (ie, short fine lines with no visible nucleus interlacing with the adjacent keratinocytes) within the epidermis, and atypical roundish cells at the DEJ.¹⁰

The distinction between an atypical nevus and a small-diameter melanoma using RCM occasionally may be challenging.¹¹ Pellacani et al¹² reported an algorithm to distinguish melanoma from atypical nevi. According to this algorithm, when at least 1 of the architectural atypia features (irregular junctional nests, short interconnections between junctional nests, and nonhomogeneous cellularity within junctional nests) and at least 1 of the cytologic atypia features (round pagetoid cells or atypical cells at the DEJ) are observed simultaneously, the lesion is diagnosed as a dysplastic nevus or a melanoma in the first step. In the second step, the RCM diagnosis of melanoma requires at least 1 of 3 parameters: roundish pagetoid cells encompassing at least 50% of the lesional area at the spinous layer, atypical cells involving at least 50% of the lesional area at the DEJ level, and nonedged papillae involving at least 10% of the lesional area.¹² Accordingly, our case corresponded with these RCM criteria for a melanoma, given that there were irregular junctional nests, atypical cells at the DEJ, and nonedged papillae involving at least 10% of the lesion.

The current limitations of RCM are the high cost of the device (approximately $58,125–$139,400 for different models), the amount of time needed to train staff in RCM units (seminars, congresses, and special courses organized by the International Confocal Working Group), and the amount of time needed for evaluation of individual lesions (15–20 minutes). However, RCM can be valuable in the clinical diagnosis of difficult lesions, as seen in our case.

Conclusion

Our case highlights the benefit of RCM in allowing the confident diagnosis and correct management of a small-diameter melanoma that turned out to be a melanoma with 0.3-mm Breslow thickness. Even so, histopathologic evaluation remains the gold standard for the diagnosis of melanoma.

Melanomas have been designated as small melanomas or micromelanomas according to their long-axis diameter (<6 mm and ≤3 mm, respectively).^1-3 Because small-diameter melanomas also have the potential to metastasize, particularly if nodular, early diagnosis can be highly rewarding. Deep melanomas with small diameters may have the same potential for metastasis as large-diameter melanomas. In this context, dermoscopy, digital dermoscopic monitoring, and total-body photography are useful in clinical practice. However, these techniques are of limited utility for small, dermoscopic feature–poor melanomas. Conversely, less than 10% of changing lesions, which are spotted via digital dermoscopic surveillance, turn out to be melanomas; therefore, simply removing all changing lesions may result in many unnecessary excisions of benign lesions.⁴

In vivo reflectance confocal microscopy (RCM) is an advanced technique that allows recognition of the architectural and cellular details of pigmented lesions. Reflectance confocal microscopy has the potential to reduce the rate of unnecessary excisions and to diminish the risk for missing a melanoma.^5-7 In meta-analyses, RCM sensitivity was reported as 90% to 93% and specificity was reported as 78% to 82% in detecting melanoma.^8,9

We describe a case that highlights the potential role of RCM in the diagnosis of small-diameter melanomas.

Case Report

A 57-year-old man with Fitzpatrick skin type III presented to the dermato-oncology unit for evaluation of multiple nevi. He was otherwise healthy and denied a history of skin cancer. Total-body skin examination with dermoscopy was performed, and several mildly atypical lesions were identified. We decided to perform digital dermoscopic monitoring. The patient’s 6-month monitoring appointment had been scheduled, but he did not arrive for the follow-up visit until 10 months after the initial examination. A lesion on the left arm, which initially was 1.5 mm in diameter, had enlarged. It was now a dark brown–gray papule with a 2.5-mm diameter (Figure 1). Dermoscopy revealed grayish globules/dots at the center of the lesion, reticular gray-blue areas, and few milialike cysts; at the periphery, a narrow rim of brownish delicate pigment network also was seen (Figure 2). The clinical and dermoscopic differential diagnosis was either an atypical nevus or an early melanoma. For a more precise diagnosis before excision, the lesion was evaluated with RCM, which takes 10 to 15 minutes to perform.

Under RCM at the epidermis level, there was a cobblestone pattern that showed a focus with mild disarrangement and few small, roundish, nucleated cells (Figure 3). A mosaic image, akin to low-magnification microscopy that enables overview of the entire lesion, at the level of the dermoepidermal junction (DEJ) showed an overall irregular meshwork pattern. Higher-magnification optical sections showed marked and diffuse (extending >10% of lesion area) architectural disorder with confluent junctional nests that were irregular to bizarre in shape and uneven in size and spacing as well as edged and nonedged papillae. At the superficial dermal level, atypical bright nucleated cells (>5 cells/mm²) were observed (Figure 4). Bright dots and/or plump bright cells within papillae also were observed. These RCM findings were highly suggestive for melanoma.

Histopathology showed an asymmetric, junctional, lentiginous, and nested proliferation of atypical epithelioid melanocytes, with few melanocytes in a pagetoid spread. There were small nests of atypical epithelioid melanocytes at the superficial dermis extending to a depth of 0.3 mm. The atypical epithelioid melanocytes displayed angulated hyperchromatic nuclei with conspicuous nucleoli and dusty brown cytoplasm. There was notable inflammation and pigment incontinence at the dermis. There was no evidence of ulceration or mitosis at the dermal component. The diagnosis of a pT1a malignant melanoma was reported (Figure 5).

Comment

A small but enlarging dark gray papule with reticular gray-blue areas under dermoscopy in a 57-year-old man is obviously suspicious for melanoma. In daily practice, this type of small-diameter melanoma is difficult to diagnose with high confidence. We balance our aim to diagnose melanomas early with the need to reduce unnecessary excisions. Reflectance confocal microscopy may allow the clinician to arrive at the correct diagnosis and management decision with confidence before excision of the lesion.

The distinction of a small-diameter melanoma from a nevus via RCM relies on evaluation of the architectural and cellular features. Findings on RCM in small-diameter melanomas have been scarcely reported in the literature; Pupelli et al¹⁰ evaluated small melanomas with a diameter of 2 to 5 mm. Among these small-diameter melanomas, the RCM features suggestive for melanomas were the presence of cytologic atypia with cellular pleomorphism, architectural disorder with irregular nests, at least 5 pagetoid cells/mm², dendrites or tangled lines (ie, short fine lines with no visible nucleus interlacing with the adjacent keratinocytes) within the epidermis, and atypical roundish cells at the DEJ.¹⁰

The distinction between an atypical nevus and a small-diameter melanoma using RCM occasionally may be challenging.¹¹ Pellacani et al¹² reported an algorithm to distinguish melanoma from atypical nevi. According to this algorithm, when at least 1 of the architectural atypia features (irregular junctional nests, short interconnections between junctional nests, and nonhomogeneous cellularity within junctional nests) and at least 1 of the cytologic atypia features (round pagetoid cells or atypical cells at the DEJ) are observed simultaneously, the lesion is diagnosed as a dysplastic nevus or a melanoma in the first step. In the second step, the RCM diagnosis of melanoma requires at least 1 of 3 parameters: roundish pagetoid cells encompassing at least 50% of the lesional area at the spinous layer, atypical cells involving at least 50% of the lesional area at the DEJ level, and nonedged papillae involving at least 10% of the lesional area.¹² Accordingly, our case corresponded with these RCM criteria for a melanoma, given that there were irregular junctional nests, atypical cells at the DEJ, and nonedged papillae involving at least 10% of the lesion.

The current limitations of RCM are the high cost of the device (approximately $58,125–$139,400 for different models), the amount of time needed to train staff in RCM units (seminars, congresses, and special courses organized by the International Confocal Working Group), and the amount of time needed for evaluation of individual lesions (15–20 minutes). However, RCM can be valuable in the clinical diagnosis of difficult lesions, as seen in our case.

Conclusion

Our case highlights the benefit of RCM in allowing the confident diagnosis and correct management of a small-diameter melanoma that turned out to be a melanoma with 0.3-mm Breslow thickness. Even so, histopathologic evaluation remains the gold standard for the diagnosis of melanoma.

To the Editor:

A 52-year-old man who was otherwise healthy and a long-distance runner presented with the sudden onset of diminished sweating on the left side of the body of 6 weeks’ duration. While training for a marathon, he reported that he perspired only on the right side of the body during runs of 12 to 15 miles; he observed a lack of sweating on the left side of the face, left side of the trunk, left arm, and left leg. This absence of sweating was accompanied by intense flushing on the right side of the face and trunk.

The patient did not take any medications. He reported no history of trauma and exhibited no neurologic deficits. A chest radiograph was negative. Thyroid function testing and a comprehensive metabolic panel were normal. Contrast-enhanced computed tomography of the chest and abdomen revealed a 4.3-cm soft-tissue mass in the left superior mediastinum that was superior to the aortic arch, posterior to the left subclavian artery in proximity to the sympathetic chain, and lateral to the trachea. The patient was diagnosed with Harlequin syndrome (HS).

Open thoracotomy was performed to remove the lesion. Analysis of the mass showed cystic areas, areas of hemorrhage (Figure 1A), and alternating zones of compact Antoni A spindle cells admixed with areas of less orderly Antoni B spindle cells within a hypocellular stroma (Figure 1B). Individual cells were characterized by eosinophilic cytoplasm and tapered nuclei. The mass appeared to be completely encapsulated. No mitotic figures were seen on multiple slides. The cells stained diffusely positive for S-100 proteins. At 6-month follow-up, the patient reported that he did not notice any return of normal sweating on the left side. However, the right-sided flushing had resolved.

Harlequin syndrome (also called the Harlequin sign) is a rare disorder of the sympathetic nervous system and should not be confused with lethal harlequin-type ichthyosis, an autosomal-recessive congenital disorder in which the affected newborn’s skin is hard and thickened over most of the body.¹ Harlequin syndrome usually is characterized by unilateral flushing and sweating that can affect the face, trunk, and extremities.² Physical stimuli, such as exercising (as in our patient), high body temperature, and the consumption of spicy or pungent food, or an emotional response can unmask or exacerbate symptoms of HS. The syndrome also can present with cluster headache.³ Harlequin syndrome is more common in females (66% of cases).⁴ Originally, the side of the face marked by increased sweating and flushing was perceived to be the pathologic side; now it is recognized that the anhidrotic side is affected by the causative pathology. The side of the face characterized by flushing might gradually darken as it compensates for lack of thermal regulation on the other side.^2,5

Usually, HS is an idiopathic condition associated with localized failure of upper thoracic sympathetic chain ganglia.⁵ A theory is that HS is part of a spectrum of autoimmune autonomic ganglionopathy.⁶ Typically, the syndrome is asymptomatic at rest, but testing can reveal an underlying sympathetic lesion.⁷ Structural lesions have been reported as a cause of the syndrome,⁶ similar to our patient.

Disrupted thermoregulatory vasodilation in HS is caused by an ipsilateral lesion of the sympathetic vasodilator neurons that innervate the face. Hemifacial anhidrosis also occurs because sudomotor neurons travel within the same pathways as vasodilator neurons.⁴

Our patient had a posterior mediastinal ancient schwannoma to the left of the subclavian artery, lateral to the trachea, with ipsilateral anhidrosis of the forehead, cheek, chin, and torso. In the medical literature, the forehead, cheek, and chin are described as being affected in HS when the lesion is located under the bifurcation of the carotid artery.^3,5 Most of the sudomotor and vasomotor fibers that innervate the face leave the spinal cord through ventral roots T2-T3⁴ (symptomatic areas are described in Figure 2), which correlates with the hypothesis that HS results from a deficit originating in the third thoracic nerve that is caused by a peripheral lesion affecting sympathetic outflow through the third thoracic root.² The location of our patient’s lesion supports this claim.

Harlequin syndrome can present simultaneously with ipsilateral Horner, Adie, and Ross syndromes.⁸ There are varying clinical presentations of Horner syndrome. Some patients with HS show autonomic ocular signs, such as miosis and ptosis, exhibiting Horner syndrome as an additional feature.⁵ Adie syndrome is characterized by tonic pupils with hyporeflexia and is unilateral in most cases. Ross syndrome is similar to Adie syndrome—including tonic pupils with hyporeflexia—in addition to a finding of segmental anhidrosis; it is bilateral in most cases.⁴

In some cases, Horner syndrome and HS originate from unilateral pharmaceutical sympathetic denervation (ie, as a consequence of paravertebral spread of local anesthetic to ipsilateral stellate ganglion).⁹ Facial nonflushing areas in HS typically are identical with anhidrotic areas¹⁰; Horner syndrome often is ipsilateral to the affected sympathetic region.¹¹

Our patient exhibited secondary HS from a tumor effect; however, an underlying tumor or infarct is absent in many cases. In primary (idiopathic) cases of HS, treatment is not recommended because the syndrome is benign.^10,11

If symptoms of HS cause notable social embarrassment, contralateral sympathectomy can be considered.^5,12 Repeated stellate ganglion block with a local anesthetic could be a less invasive treatment option.¹³ When considered on a case-by-case-basis, botulinum toxin type A has been effective as a treatment of compensatory hyperhidrosis on the unaffected side.¹⁴

In cases of secondary HS, surgical removal of the lesion may alleviate symptoms, though thoracotomy in our patient to remove the schwannoma did not alleviate anhidrosis. The Table lists treatment options for primary and secondary HS.^4,5,11

To the Editor:

A 52-year-old man who was otherwise healthy and a long-distance runner presented with the sudden onset of diminished sweating on the left side of the body of 6 weeks’ duration. While training for a marathon, he reported that he perspired only on the right side of the body during runs of 12 to 15 miles; he observed a lack of sweating on the left side of the face, left side of the trunk, left arm, and left leg. This absence of sweating was accompanied by intense flushing on the right side of the face and trunk.

The patient did not take any medications. He reported no history of trauma and exhibited no neurologic deficits. A chest radiograph was negative. Thyroid function testing and a comprehensive metabolic panel were normal. Contrast-enhanced computed tomography of the chest and abdomen revealed a 4.3-cm soft-tissue mass in the left superior mediastinum that was superior to the aortic arch, posterior to the left subclavian artery in proximity to the sympathetic chain, and lateral to the trachea. The patient was diagnosed with Harlequin syndrome (HS).

Open thoracotomy was performed to remove the lesion. Analysis of the mass showed cystic areas, areas of hemorrhage (Figure 1A), and alternating zones of compact Antoni A spindle cells admixed with areas of less orderly Antoni B spindle cells within a hypocellular stroma (Figure 1B). Individual cells were characterized by eosinophilic cytoplasm and tapered nuclei. The mass appeared to be completely encapsulated. No mitotic figures were seen on multiple slides. The cells stained diffusely positive for S-100 proteins. At 6-month follow-up, the patient reported that he did not notice any return of normal sweating on the left side. However, the right-sided flushing had resolved.

Harlequin syndrome (also called the Harlequin sign) is a rare disorder of the sympathetic nervous system and should not be confused with lethal harlequin-type ichthyosis, an autosomal-recessive congenital disorder in which the affected newborn’s skin is hard and thickened over most of the body.¹ Harlequin syndrome usually is characterized by unilateral flushing and sweating that can affect the face, trunk, and extremities.² Physical stimuli, such as exercising (as in our patient), high body temperature, and the consumption of spicy or pungent food, or an emotional response can unmask or exacerbate symptoms of HS. The syndrome also can present with cluster headache.³ Harlequin syndrome is more common in females (66% of cases).⁴ Originally, the side of the face marked by increased sweating and flushing was perceived to be the pathologic side; now it is recognized that the anhidrotic side is affected by the causative pathology. The side of the face characterized by flushing might gradually darken as it compensates for lack of thermal regulation on the other side.^2,5

Usually, HS is an idiopathic condition associated with localized failure of upper thoracic sympathetic chain ganglia.⁵ A theory is that HS is part of a spectrum of autoimmune autonomic ganglionopathy.⁶ Typically, the syndrome is asymptomatic at rest, but testing can reveal an underlying sympathetic lesion.⁷ Structural lesions have been reported as a cause of the syndrome,⁶ similar to our patient.

Disrupted thermoregulatory vasodilation in HS is caused by an ipsilateral lesion of the sympathetic vasodilator neurons that innervate the face. Hemifacial anhidrosis also occurs because sudomotor neurons travel within the same pathways as vasodilator neurons.⁴

Our patient had a posterior mediastinal ancient schwannoma to the left of the subclavian artery, lateral to the trachea, with ipsilateral anhidrosis of the forehead, cheek, chin, and torso. In the medical literature, the forehead, cheek, and chin are described as being affected in HS when the lesion is located under the bifurcation of the carotid artery.^3,5 Most of the sudomotor and vasomotor fibers that innervate the face leave the spinal cord through ventral roots T2-T3⁴ (symptomatic areas are described in Figure 2), which correlates with the hypothesis that HS results from a deficit originating in the third thoracic nerve that is caused by a peripheral lesion affecting sympathetic outflow through the third thoracic root.² The location of our patient’s lesion supports this claim.

Harlequin syndrome can present simultaneously with ipsilateral Horner, Adie, and Ross syndromes.⁸ There are varying clinical presentations of Horner syndrome. Some patients with HS show autonomic ocular signs, such as miosis and ptosis, exhibiting Horner syndrome as an additional feature.⁵ Adie syndrome is characterized by tonic pupils with hyporeflexia and is unilateral in most cases. Ross syndrome is similar to Adie syndrome—including tonic pupils with hyporeflexia—in addition to a finding of segmental anhidrosis; it is bilateral in most cases.⁴

In some cases, Horner syndrome and HS originate from unilateral pharmaceutical sympathetic denervation (ie, as a consequence of paravertebral spread of local anesthetic to ipsilateral stellate ganglion).⁹ Facial nonflushing areas in HS typically are identical with anhidrotic areas¹⁰; Horner syndrome often is ipsilateral to the affected sympathetic region.¹¹

Our patient exhibited secondary HS from a tumor effect; however, an underlying tumor or infarct is absent in many cases. In primary (idiopathic) cases of HS, treatment is not recommended because the syndrome is benign.^10,11

If symptoms of HS cause notable social embarrassment, contralateral sympathectomy can be considered.^5,12 Repeated stellate ganglion block with a local anesthetic could be a less invasive treatment option.¹³ When considered on a case-by-case-basis, botulinum toxin type A has been effective as a treatment of compensatory hyperhidrosis on the unaffected side.¹⁴

In cases of secondary HS, surgical removal of the lesion may alleviate symptoms, though thoracotomy in our patient to remove the schwannoma did not alleviate anhidrosis. The Table lists treatment options for primary and secondary HS.^4,5,11

To the Editor:

A 52-year-old man who was otherwise healthy and a long-distance runner presented with the sudden onset of diminished sweating on the left side of the body of 6 weeks’ duration. While training for a marathon, he reported that he perspired only on the right side of the body during runs of 12 to 15 miles; he observed a lack of sweating on the left side of the face, left side of the trunk, left arm, and left leg. This absence of sweating was accompanied by intense flushing on the right side of the face and trunk.

The patient did not take any medications. He reported no history of trauma and exhibited no neurologic deficits. A chest radiograph was negative. Thyroid function testing and a comprehensive metabolic panel were normal. Contrast-enhanced computed tomography of the chest and abdomen revealed a 4.3-cm soft-tissue mass in the left superior mediastinum that was superior to the aortic arch, posterior to the left subclavian artery in proximity to the sympathetic chain, and lateral to the trachea. The patient was diagnosed with Harlequin syndrome (HS).

Open thoracotomy was performed to remove the lesion. Analysis of the mass showed cystic areas, areas of hemorrhage (Figure 1A), and alternating zones of compact Antoni A spindle cells admixed with areas of less orderly Antoni B spindle cells within a hypocellular stroma (Figure 1B). Individual cells were characterized by eosinophilic cytoplasm and tapered nuclei. The mass appeared to be completely encapsulated. No mitotic figures were seen on multiple slides. The cells stained diffusely positive for S-100 proteins. At 6-month follow-up, the patient reported that he did not notice any return of normal sweating on the left side. However, the right-sided flushing had resolved.

Harlequin syndrome (also called the Harlequin sign) is a rare disorder of the sympathetic nervous system and should not be confused with lethal harlequin-type ichthyosis, an autosomal-recessive congenital disorder in which the affected newborn’s skin is hard and thickened over most of the body.¹ Harlequin syndrome usually is characterized by unilateral flushing and sweating that can affect the face, trunk, and extremities.² Physical stimuli, such as exercising (as in our patient), high body temperature, and the consumption of spicy or pungent food, or an emotional response can unmask or exacerbate symptoms of HS. The syndrome also can present with cluster headache.³ Harlequin syndrome is more common in females (66% of cases).⁴ Originally, the side of the face marked by increased sweating and flushing was perceived to be the pathologic side; now it is recognized that the anhidrotic side is affected by the causative pathology. The side of the face characterized by flushing might gradually darken as it compensates for lack of thermal regulation on the other side.^2,5

Usually, HS is an idiopathic condition associated with localized failure of upper thoracic sympathetic chain ganglia.⁵ A theory is that HS is part of a spectrum of autoimmune autonomic ganglionopathy.⁶ Typically, the syndrome is asymptomatic at rest, but testing can reveal an underlying sympathetic lesion.⁷ Structural lesions have been reported as a cause of the syndrome,⁶ similar to our patient.

Disrupted thermoregulatory vasodilation in HS is caused by an ipsilateral lesion of the sympathetic vasodilator neurons that innervate the face. Hemifacial anhidrosis also occurs because sudomotor neurons travel within the same pathways as vasodilator neurons.⁴

Our patient had a posterior mediastinal ancient schwannoma to the left of the subclavian artery, lateral to the trachea, with ipsilateral anhidrosis of the forehead, cheek, chin, and torso. In the medical literature, the forehead, cheek, and chin are described as being affected in HS when the lesion is located under the bifurcation of the carotid artery.^3,5 Most of the sudomotor and vasomotor fibers that innervate the face leave the spinal cord through ventral roots T2-T3⁴ (symptomatic areas are described in Figure 2), which correlates with the hypothesis that HS results from a deficit originating in the third thoracic nerve that is caused by a peripheral lesion affecting sympathetic outflow through the third thoracic root.² The location of our patient’s lesion supports this claim.

Harlequin syndrome can present simultaneously with ipsilateral Horner, Adie, and Ross syndromes.⁸ There are varying clinical presentations of Horner syndrome. Some patients with HS show autonomic ocular signs, such as miosis and ptosis, exhibiting Horner syndrome as an additional feature.⁵ Adie syndrome is characterized by tonic pupils with hyporeflexia and is unilateral in most cases. Ross syndrome is similar to Adie syndrome—including tonic pupils with hyporeflexia—in addition to a finding of segmental anhidrosis; it is bilateral in most cases.⁴

In some cases, Horner syndrome and HS originate from unilateral pharmaceutical sympathetic denervation (ie, as a consequence of paravertebral spread of local anesthetic to ipsilateral stellate ganglion).⁹ Facial nonflushing areas in HS typically are identical with anhidrotic areas¹⁰; Horner syndrome often is ipsilateral to the affected sympathetic region.¹¹

Our patient exhibited secondary HS from a tumor effect; however, an underlying tumor or infarct is absent in many cases. In primary (idiopathic) cases of HS, treatment is not recommended because the syndrome is benign.^10,11

If symptoms of HS cause notable social embarrassment, contralateral sympathectomy can be considered.^5,12 Repeated stellate ganglion block with a local anesthetic could be a less invasive treatment option.¹³ When considered on a case-by-case-basis, botulinum toxin type A has been effective as a treatment of compensatory hyperhidrosis on the unaffected side.¹⁴

In cases of secondary HS, surgical removal of the lesion may alleviate symptoms, though thoracotomy in our patient to remove the schwannoma did not alleviate anhidrosis. The Table lists treatment options for primary and secondary HS.^4,5,11

To the Editor:

A 53-year-old Hispanic woman presented to our dermatology clinic for evaluation of an expanding plaque on the right cheek of 2 months’ duration. The patient stated the plaque began as a pimple, which she picked with subsequent spread laterally across the cheek. The area was intermittently tender, but she denied tingling, burning, or pruritus of the site. She had been treated with doxycycline and amoxicillin–clavulanic acid prior to presentation without improvement. She had a history of levamisole-induced vasculitis approximately 6 months prior. A review of systems was notable for diffuse joint pain. The patient denied tobacco, alcohol, or illicit drug use in the preceding 3 months and denied any changes in her medications or in health within the last year.

Physical examination revealed a well-appearing, alert, and afebrile patient with a pink, well-demarcated plaque on the right cheek (Figure 1). The borders of the plaque were indurated, and the lateral aspect of the plaque was eroded secondary to digital manipulation by the patient. She had no cervical lymphadenopathy. There were no other abnormal cutaneous findings.

There is a broad differential diagnosis for a pink expanding plaque on the face, which requires histopathologic correlation for correct diagnosis. Three broad categories in the differential are infectious (eg, bacterial, fungal), medication related (eg, fixed drug eruption), and granulomatous (eg, granuloma faciale [GF], sarcoidosis, tumid lupus, leprosy, granulomatous rosacea). A biopsy of the lesion revealed a mixed inflammatory cell dermal infiltrate with perivascular accentuation and intense vasculitis that was consistent with GF (Figure 2). Gomori methenamine-silver, periodic acid–Schiff, Fite-Faraco, acid-fast bacilli, and Gram staining were negative for organisms. Tissue cultures were negative for bacterial, mycobacterial, and fungal etiology. The patient was started on high-potency topical steroids with a 50% improvement in the appearance of the skin lesion at 1-month follow-up.

Granuloma faciale is a rare chronic inflammatory dermatosis with a predilection for the face that is difficult to diagnose and treat. The diagnosis is based on clinical and histologic findings, and it typically presents as single or multiple, well-demarcated, red-brown nodules, papules, or plaques that range from several millimeters to centimeters in diameter.^1,2 Extrafacial lesions may be seen.³ Granuloma faciale usually is asymptomatic but occasionally has associated pruritus and rarely ulceration. The prevalence and pathophysiology of GF is not well defined; however, GF more commonly is reported in middle-aged White males.¹

Histologic examination of GF reveals a mixed inflammatory cellular infiltrate in the upper dermis. A grenz zone, which is a narrow area of the papillary dermis uninvolved by the underlying pathology, may be seen.¹ Contrary to the name, granulomas are not found histologically. Rather, vascular changes or damage frequently are present and may indicate a small vessel vasculitis pathologic mechanism. Granuloma faciale also has been associated with follicular ostia accentuation and telangiectases.⁴

Many cases of GF have been misdiagnosed as sarcoidosis, lymphoma, lupus, and basal cell carcinoma.¹ In addition, GF shares many clinical and histologic features with erythema elevatum diutinum (EED). However, the defining features that suggest EED over GF is that EED has a predilection for the skin overlying the joints. Histopathologically, EED displays granulomas and fibrosis with few eosinophils.^5,6

The variable response of GF to treatments and lack of efficacy data have contributed to the complexity and uncertainty of managing GF. The current first-line therapies are topical tacrolimus,⁷ cryotherapy,⁸ or corticosteroid therapy.⁹

To the Editor:

A 53-year-old Hispanic woman presented to our dermatology clinic for evaluation of an expanding plaque on the right cheek of 2 months’ duration. The patient stated the plaque began as a pimple, which she picked with subsequent spread laterally across the cheek. The area was intermittently tender, but she denied tingling, burning, or pruritus of the site. She had been treated with doxycycline and amoxicillin–clavulanic acid prior to presentation without improvement. She had a history of levamisole-induced vasculitis approximately 6 months prior. A review of systems was notable for diffuse joint pain. The patient denied tobacco, alcohol, or illicit drug use in the preceding 3 months and denied any changes in her medications or in health within the last year.

Physical examination revealed a well-appearing, alert, and afebrile patient with a pink, well-demarcated plaque on the right cheek (Figure 1). The borders of the plaque were indurated, and the lateral aspect of the plaque was eroded secondary to digital manipulation by the patient. She had no cervical lymphadenopathy. There were no other abnormal cutaneous findings.

There is a broad differential diagnosis for a pink expanding plaque on the face, which requires histopathologic correlation for correct diagnosis. Three broad categories in the differential are infectious (eg, bacterial, fungal), medication related (eg, fixed drug eruption), and granulomatous (eg, granuloma faciale [GF], sarcoidosis, tumid lupus, leprosy, granulomatous rosacea). A biopsy of the lesion revealed a mixed inflammatory cell dermal infiltrate with perivascular accentuation and intense vasculitis that was consistent with GF (Figure 2). Gomori methenamine-silver, periodic acid–Schiff, Fite-Faraco, acid-fast bacilli, and Gram staining were negative for organisms. Tissue cultures were negative for bacterial, mycobacterial, and fungal etiology. The patient was started on high-potency topical steroids with a 50% improvement in the appearance of the skin lesion at 1-month follow-up.

Granuloma faciale is a rare chronic inflammatory dermatosis with a predilection for the face that is difficult to diagnose and treat. The diagnosis is based on clinical and histologic findings, and it typically presents as single or multiple, well-demarcated, red-brown nodules, papules, or plaques that range from several millimeters to centimeters in diameter.^1,2 Extrafacial lesions may be seen.³ Granuloma faciale usually is asymptomatic but occasionally has associated pruritus and rarely ulceration. The prevalence and pathophysiology of GF is not well defined; however, GF more commonly is reported in middle-aged White males.¹

Histologic examination of GF reveals a mixed inflammatory cellular infiltrate in the upper dermis. A grenz zone, which is a narrow area of the papillary dermis uninvolved by the underlying pathology, may be seen.¹ Contrary to the name, granulomas are not found histologically. Rather, vascular changes or damage frequently are present and may indicate a small vessel vasculitis pathologic mechanism. Granuloma faciale also has been associated with follicular ostia accentuation and telangiectases.⁴

Many cases of GF have been misdiagnosed as sarcoidosis, lymphoma, lupus, and basal cell carcinoma.¹ In addition, GF shares many clinical and histologic features with erythema elevatum diutinum (EED). However, the defining features that suggest EED over GF is that EED has a predilection for the skin overlying the joints. Histopathologically, EED displays granulomas and fibrosis with few eosinophils.^5,6

The variable response of GF to treatments and lack of efficacy data have contributed to the complexity and uncertainty of managing GF. The current first-line therapies are topical tacrolimus,⁷ cryotherapy,⁸ or corticosteroid therapy.⁹

To the Editor:

A 53-year-old Hispanic woman presented to our dermatology clinic for evaluation of an expanding plaque on the right cheek of 2 months’ duration. The patient stated the plaque began as a pimple, which she picked with subsequent spread laterally across the cheek. The area was intermittently tender, but she denied tingling, burning, or pruritus of the site. She had been treated with doxycycline and amoxicillin–clavulanic acid prior to presentation without improvement. She had a history of levamisole-induced vasculitis approximately 6 months prior. A review of systems was notable for diffuse joint pain. The patient denied tobacco, alcohol, or illicit drug use in the preceding 3 months and denied any changes in her medications or in health within the last year.

Physical examination revealed a well-appearing, alert, and afebrile patient with a pink, well-demarcated plaque on the right cheek (Figure 1). The borders of the plaque were indurated, and the lateral aspect of the plaque was eroded secondary to digital manipulation by the patient. She had no cervical lymphadenopathy. There were no other abnormal cutaneous findings.

There is a broad differential diagnosis for a pink expanding plaque on the face, which requires histopathologic correlation for correct diagnosis. Three broad categories in the differential are infectious (eg, bacterial, fungal), medication related (eg, fixed drug eruption), and granulomatous (eg, granuloma faciale [GF], sarcoidosis, tumid lupus, leprosy, granulomatous rosacea). A biopsy of the lesion revealed a mixed inflammatory cell dermal infiltrate with perivascular accentuation and intense vasculitis that was consistent with GF (Figure 2). Gomori methenamine-silver, periodic acid–Schiff, Fite-Faraco, acid-fast bacilli, and Gram staining were negative for organisms. Tissue cultures were negative for bacterial, mycobacterial, and fungal etiology. The patient was started on high-potency topical steroids with a 50% improvement in the appearance of the skin lesion at 1-month follow-up.

Granuloma faciale is a rare chronic inflammatory dermatosis with a predilection for the face that is difficult to diagnose and treat. The diagnosis is based on clinical and histologic findings, and it typically presents as single or multiple, well-demarcated, red-brown nodules, papules, or plaques that range from several millimeters to centimeters in diameter.^1,2 Extrafacial lesions may be seen.³ Granuloma faciale usually is asymptomatic but occasionally has associated pruritus and rarely ulceration. The prevalence and pathophysiology of GF is not well defined; however, GF more commonly is reported in middle-aged White males.¹

Histologic examination of GF reveals a mixed inflammatory cellular infiltrate in the upper dermis. A grenz zone, which is a narrow area of the papillary dermis uninvolved by the underlying pathology, may be seen.¹ Contrary to the name, granulomas are not found histologically. Rather, vascular changes or damage frequently are present and may indicate a small vessel vasculitis pathologic mechanism. Granuloma faciale also has been associated with follicular ostia accentuation and telangiectases.⁴

Many cases of GF have been misdiagnosed as sarcoidosis, lymphoma, lupus, and basal cell carcinoma.¹ In addition, GF shares many clinical and histologic features with erythema elevatum diutinum (EED). However, the defining features that suggest EED over GF is that EED has a predilection for the skin overlying the joints. Histopathologically, EED displays granulomas and fibrosis with few eosinophils.^5,6

The variable response of GF to treatments and lack of efficacy data have contributed to the complexity and uncertainty of managing GF. The current first-line therapies are topical tacrolimus,⁷ cryotherapy,⁸ or corticosteroid therapy.⁹

The Diagnosis: Cutaneous B-cell Lymphoma

Shave biopsies of 3 lesions revealed a dense, diffuse, atypical lymphoid infiltrate occupying the entirety of the dermis and obscuring the dermoepidermal junction. The infiltrate consisted predominantly of largesized lymphoid cells with fine chromatin and conspicuous nucleoli (Figure). Immunohistochemistry was positive for CD45 and CD20, indicating B-cell lineage. Bcl-2, multiple myeloma oncogene 1, and forkhead box protein P1 also were expressed in the vast majority of lesional cells, distinguishing the lesion from other forms of cutaneous B-cell lymphomas.¹ These findings were consistent with large B-cell lymphoma with a high proliferation index, consistent with primary cutaneous diffuse large B-cell lymphoma, leg type, which often presents on the lower leg.² The patient had a negative systemic workup including bone marrow biopsy. He was started on the R-CEOP (rituximab, cyclophosphamide, etoposide, vincristine, prednisone) chemotherapy regimen.

Primary cutaneous diffuse large B-cell lymphoma, leg type, is an intermediately aggressive and rare form of B-cell lymphoma with a poor prognosis that primarily affects elderly female patients. Primary cutaneous diffuse large B-cell lymphoma, leg type, accounts for only 1% to 3% of cutaneous lymphomas and approximately 10% to 20% of primary cutaneous B-cell lymphomas.² It typically presents as multiple red-brown or bluish nodules on the lower extremities or trunk. Presentation as a solitary nodule also is possible.^1,2 Histologic analysis of primary cutaneous diffuse large B-cell lymphoma, leg type, reveals large cells with round nuclei (immunoblasts and centroblasts), and the immunohistochemical profile shows strong Bcl-2 expression often accompanied by the multiple myeloma oncogene 1 protein.³ The 5-year survival rate is approximately 50%, which is lower than other types of primary cutaneous B-cell lymphomas, and the progression of disease is characterized by frequent relapses and involvement of extracutaneous regions such as the lymph nodes, bone marrow, and central nervous system.^1,2,4 Patients with multiple tumors on the leg have a particularly poor prognosis; in particular, having 1 or more lesions on the leg results in a 43% 3-year survival rate while having multiple lesions has a 36% 3-year survival rate compared with a 77% 3-year survival rate for patients with the non–leg subtype or a single lesion.3 Treatment with rituximab has been shown to be effective in at least short-term control of the disease, and the R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) regimen is the standard of treatment.^3,4

Primary cutaneous diffuse large B-cell lymphoma, leg type, can mimic multiple other cutaneous presentations of disease. Myeloid sarcoma (leukemia cutis) is a rare condition that presents as an extramedullary tumor often simultaneously with the onset or relapse of acute myeloid leukemia.⁵ Our patient had no history of leukemia, but myeloid sarcoma may predate acute myeloid leukemia in about a quarter of cases.⁵ It most commonly presents histologically as a diffuse dermal infiltrate that splays between collagen bundles and often is associated with an overlying Grenz zone. A nodular, or perivascular and periadnexal, pattern also may be seen. Upon closer inspection, the infiltrate is composed of immature myeloid cells (blasts) with background inflammation occasionally containing eosinophils. The immunohistochemical profile varies depending on the type of differentiation and degree of maturity of the cells. The histologic findings in our patient were inconsistent with myeloid sarcoma.

Erythema elevatum diutinum (EED) usually presents as dark red, brown, or violaceous papules or plaques and often is found on the extensor surfaces. It often is associated with hematologic abnormalities as well as recurrent bacterial or viral infections.⁶ Histologically, EED initially manifests as leukocytoclastic vasculitis with a mixed inflammatory infiltrate typically featuring an abundance of neutrophils, making this condition unlikely in this case. As the lesion progresses, fibrosis and scarring ensue as inflammation wanes. The fibrosis often is described as having an onion skin–like pattern, which is characteristic of established EED lesions. Our patient had no history of vasculitis, and the histologic findings were inconsistent with EED.

Angiosarcoma can present as a central nodule surrounded by an erythematous plaque. Although potentially clinically similar to primary cutaneous diffuse large B-cell lymphoma, leg type, angiosarcoma was unlikely in this case because of an absence of lymphedema and no history of radiation to the leg, both of which are key historical features of angiosarcoma.⁷ Additionally, the histology of cutaneous angiosarcoma is marked by vascular proliferation, which was not seen in the lesion biopsied in our patient. The histology of angiosarcoma is that of an atypical vascular proliferation, and a hallmark feature is infiltration between collagen, often referred to as giving the appearance of dissection between collagen bundles. The degree of atypia can vary widely, and epithelioid variants exist, producing a potential diagnostic pitfall. Lesional cells are positive for vascular markers, which can be used for confirmation of the endothelial lineage.

Sarcoidosis is notorious for its mimicry, which can be the case both clinically and histologically. Characteristic pathology of sarcoidosis is that of well-formed epithelioid granulomas with minimal associated inflammation and lack of caseating necrosis. Our patient had no known history of systemic sarcoidosis, and the pathologic features of noncaseating granulomas were not present. As a diagnosis of exclusion, correlation with special stains and culture studies is necessary to exclude an infectious process. The differential diagnosis for sarcoidal granulomatous dermatitis also includes foreign body reaction, inflammatory bowel disease, and granulomatous cheilitis, among others.

The Diagnosis: Cutaneous B-cell Lymphoma

Shave biopsies of 3 lesions revealed a dense, diffuse, atypical lymphoid infiltrate occupying the entirety of the dermis and obscuring the dermoepidermal junction. The infiltrate consisted predominantly of largesized lymphoid cells with fine chromatin and conspicuous nucleoli (Figure). Immunohistochemistry was positive for CD45 and CD20, indicating B-cell lineage. Bcl-2, multiple myeloma oncogene 1, and forkhead box protein P1 also were expressed in the vast majority of lesional cells, distinguishing the lesion from other forms of cutaneous B-cell lymphomas.¹ These findings were consistent with large B-cell lymphoma with a high proliferation index, consistent with primary cutaneous diffuse large B-cell lymphoma, leg type, which often presents on the lower leg.² The patient had a negative systemic workup including bone marrow biopsy. He was started on the R-CEOP (rituximab, cyclophosphamide, etoposide, vincristine, prednisone) chemotherapy regimen.

Primary cutaneous diffuse large B-cell lymphoma, leg type, is an intermediately aggressive and rare form of B-cell lymphoma with a poor prognosis that primarily affects elderly female patients. Primary cutaneous diffuse large B-cell lymphoma, leg type, accounts for only 1% to 3% of cutaneous lymphomas and approximately 10% to 20% of primary cutaneous B-cell lymphomas.² It typically presents as multiple red-brown or bluish nodules on the lower extremities or trunk. Presentation as a solitary nodule also is possible.^1,2 Histologic analysis of primary cutaneous diffuse large B-cell lymphoma, leg type, reveals large cells with round nuclei (immunoblasts and centroblasts), and the immunohistochemical profile shows strong Bcl-2 expression often accompanied by the multiple myeloma oncogene 1 protein.³ The 5-year survival rate is approximately 50%, which is lower than other types of primary cutaneous B-cell lymphomas, and the progression of disease is characterized by frequent relapses and involvement of extracutaneous regions such as the lymph nodes, bone marrow, and central nervous system.^1,2,4 Patients with multiple tumors on the leg have a particularly poor prognosis; in particular, having 1 or more lesions on the leg results in a 43% 3-year survival rate while having multiple lesions has a 36% 3-year survival rate compared with a 77% 3-year survival rate for patients with the non–leg subtype or a single lesion.3 Treatment with rituximab has been shown to be effective in at least short-term control of the disease, and the R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) regimen is the standard of treatment.^3,4

Primary cutaneous diffuse large B-cell lymphoma, leg type, can mimic multiple other cutaneous presentations of disease. Myeloid sarcoma (leukemia cutis) is a rare condition that presents as an extramedullary tumor often simultaneously with the onset or relapse of acute myeloid leukemia.⁵ Our patient had no history of leukemia, but myeloid sarcoma may predate acute myeloid leukemia in about a quarter of cases.⁵ It most commonly presents histologically as a diffuse dermal infiltrate that splays between collagen bundles and often is associated with an overlying Grenz zone. A nodular, or perivascular and periadnexal, pattern also may be seen. Upon closer inspection, the infiltrate is composed of immature myeloid cells (blasts) with background inflammation occasionally containing eosinophils. The immunohistochemical profile varies depending on the type of differentiation and degree of maturity of the cells. The histologic findings in our patient were inconsistent with myeloid sarcoma.

Erythema elevatum diutinum (EED) usually presents as dark red, brown, or violaceous papules or plaques and often is found on the extensor surfaces. It often is associated with hematologic abnormalities as well as recurrent bacterial or viral infections.⁶ Histologically, EED initially manifests as leukocytoclastic vasculitis with a mixed inflammatory infiltrate typically featuring an abundance of neutrophils, making this condition unlikely in this case. As the lesion progresses, fibrosis and scarring ensue as inflammation wanes. The fibrosis often is described as having an onion skin–like pattern, which is characteristic of established EED lesions. Our patient had no history of vasculitis, and the histologic findings were inconsistent with EED.

Angiosarcoma can present as a central nodule surrounded by an erythematous plaque. Although potentially clinically similar to primary cutaneous diffuse large B-cell lymphoma, leg type, angiosarcoma was unlikely in this case because of an absence of lymphedema and no history of radiation to the leg, both of which are key historical features of angiosarcoma.⁷ Additionally, the histology of cutaneous angiosarcoma is marked by vascular proliferation, which was not seen in the lesion biopsied in our patient. The histology of angiosarcoma is that of an atypical vascular proliferation, and a hallmark feature is infiltration between collagen, often referred to as giving the appearance of dissection between collagen bundles. The degree of atypia can vary widely, and epithelioid variants exist, producing a potential diagnostic pitfall. Lesional cells are positive for vascular markers, which can be used for confirmation of the endothelial lineage.

Sarcoidosis is notorious for its mimicry, which can be the case both clinically and histologically. Characteristic pathology of sarcoidosis is that of well-formed epithelioid granulomas with minimal associated inflammation and lack of caseating necrosis. Our patient had no known history of systemic sarcoidosis, and the pathologic features of noncaseating granulomas were not present. As a diagnosis of exclusion, correlation with special stains and culture studies is necessary to exclude an infectious process. The differential diagnosis for sarcoidal granulomatous dermatitis also includes foreign body reaction, inflammatory bowel disease, and granulomatous cheilitis, among others.

The Diagnosis: Cutaneous B-cell Lymphoma

Shave biopsies of 3 lesions revealed a dense, diffuse, atypical lymphoid infiltrate occupying the entirety of the dermis and obscuring the dermoepidermal junction. The infiltrate consisted predominantly of largesized lymphoid cells with fine chromatin and conspicuous nucleoli (Figure). Immunohistochemistry was positive for CD45 and CD20, indicating B-cell lineage. Bcl-2, multiple myeloma oncogene 1, and forkhead box protein P1 also were expressed in the vast majority of lesional cells, distinguishing the lesion from other forms of cutaneous B-cell lymphomas.¹ These findings were consistent with large B-cell lymphoma with a high proliferation index, consistent with primary cutaneous diffuse large B-cell lymphoma, leg type, which often presents on the lower leg.² The patient had a negative systemic workup including bone marrow biopsy. He was started on the R-CEOP (rituximab, cyclophosphamide, etoposide, vincristine, prednisone) chemotherapy regimen.

Primary cutaneous diffuse large B-cell lymphoma, leg type, is an intermediately aggressive and rare form of B-cell lymphoma with a poor prognosis that primarily affects elderly female patients. Primary cutaneous diffuse large B-cell lymphoma, leg type, accounts for only 1% to 3% of cutaneous lymphomas and approximately 10% to 20% of primary cutaneous B-cell lymphomas.² It typically presents as multiple red-brown or bluish nodules on the lower extremities or trunk. Presentation as a solitary nodule also is possible.^1,2 Histologic analysis of primary cutaneous diffuse large B-cell lymphoma, leg type, reveals large cells with round nuclei (immunoblasts and centroblasts), and the immunohistochemical profile shows strong Bcl-2 expression often accompanied by the multiple myeloma oncogene 1 protein.³ The 5-year survival rate is approximately 50%, which is lower than other types of primary cutaneous B-cell lymphomas, and the progression of disease is characterized by frequent relapses and involvement of extracutaneous regions such as the lymph nodes, bone marrow, and central nervous system.^1,2,4 Patients with multiple tumors on the leg have a particularly poor prognosis; in particular, having 1 or more lesions on the leg results in a 43% 3-year survival rate while having multiple lesions has a 36% 3-year survival rate compared with a 77% 3-year survival rate for patients with the non–leg subtype or a single lesion.3 Treatment with rituximab has been shown to be effective in at least short-term control of the disease, and the R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) regimen is the standard of treatment.^3,4

Primary cutaneous diffuse large B-cell lymphoma, leg type, can mimic multiple other cutaneous presentations of disease. Myeloid sarcoma (leukemia cutis) is a rare condition that presents as an extramedullary tumor often simultaneously with the onset or relapse of acute myeloid leukemia.⁵ Our patient had no history of leukemia, but myeloid sarcoma may predate acute myeloid leukemia in about a quarter of cases.⁵ It most commonly presents histologically as a diffuse dermal infiltrate that splays between collagen bundles and often is associated with an overlying Grenz zone. A nodular, or perivascular and periadnexal, pattern also may be seen. Upon closer inspection, the infiltrate is composed of immature myeloid cells (blasts) with background inflammation occasionally containing eosinophils. The immunohistochemical profile varies depending on the type of differentiation and degree of maturity of the cells. The histologic findings in our patient were inconsistent with myeloid sarcoma.

Erythema elevatum diutinum (EED) usually presents as dark red, brown, or violaceous papules or plaques and often is found on the extensor surfaces. It often is associated with hematologic abnormalities as well as recurrent bacterial or viral infections.⁶ Histologically, EED initially manifests as leukocytoclastic vasculitis with a mixed inflammatory infiltrate typically featuring an abundance of neutrophils, making this condition unlikely in this case. As the lesion progresses, fibrosis and scarring ensue as inflammation wanes. The fibrosis often is described as having an onion skin–like pattern, which is characteristic of established EED lesions. Our patient had no history of vasculitis, and the histologic findings were inconsistent with EED.

Angiosarcoma can present as a central nodule surrounded by an erythematous plaque. Although potentially clinically similar to primary cutaneous diffuse large B-cell lymphoma, leg type, angiosarcoma was unlikely in this case because of an absence of lymphedema and no history of radiation to the leg, both of which are key historical features of angiosarcoma.⁷ Additionally, the histology of cutaneous angiosarcoma is marked by vascular proliferation, which was not seen in the lesion biopsied in our patient. The histology of angiosarcoma is that of an atypical vascular proliferation, and a hallmark feature is infiltration between collagen, often referred to as giving the appearance of dissection between collagen bundles. The degree of atypia can vary widely, and epithelioid variants exist, producing a potential diagnostic pitfall. Lesional cells are positive for vascular markers, which can be used for confirmation of the endothelial lineage.

Sarcoidosis is notorious for its mimicry, which can be the case both clinically and histologically. Characteristic pathology of sarcoidosis is that of well-formed epithelioid granulomas with minimal associated inflammation and lack of caseating necrosis. Our patient had no known history of systemic sarcoidosis, and the pathologic features of noncaseating granulomas were not present. As a diagnosis of exclusion, correlation with special stains and culture studies is necessary to exclude an infectious process. The differential diagnosis for sarcoidal granulomatous dermatitis also includes foreign body reaction, inflammatory bowel disease, and granulomatous cheilitis, among others.

BOSTON – Although skin biopsy remains the gold standard for diagnosing early-stage melanoma, advances in genetic expression profiling are helping dermatologists provide a nuanced approach to managing suspicious lesions.

One such test, the Pigmented Lesional Assay (PLA) uses adhesive patches applied to lesions of concern at the bedside to extract RNA from the stratum corneum to help determine the risk for melanoma.

At the annual meeting of the American Academy of Dermatology, Caroline C. Kim, MD, director of melanoma and pigmented lesion clinics at Newton Wellesley Dermatology, Wellesley Hills, Mass., and Tufts Medical Center, Boston, spoke about the PLA, which uses genetic expression profiling to measure the expression level of specific genes that are associated with melanoma: PRAME (preferentially expressed antigen in melanoma) and LINC00518 (LINC). There are four possible results of the test: Aberrant expression of both LINC and PRAME (high risk); aberrant expression of a single gene (moderate risk); aberrant expression of neither gene (low risk); or inconclusive.

Validation data have shown a sensitivity of 91% and a specificity of 69% for the PLA, with a 99% negative predictive value; so a lesion that tested negative by PLA has a less than 1% chance of being melanoma. In addition, a study published in 2020 found that the addition of TERT (telomerase reverse transcriptase) mutation analyses increased the sensitivity of the PLA to 97%.

While the high negative predictive value is helpful to consider in clinical scenarios to rule-out melanoma for borderline lesions, one must consider the positive predictive value as well and how this may impact clinical care, Dr. Kim said. In a study examining outcomes of 381 lesions, 51 were PLA positive (single or double) and were biopsied, of which 19 (37%) revealed a melanoma diagnosis. In a large U.S. registry study of 3,418 lesions, 324 lesions that were PLA double positive were biopsied, with 18.7% revealing a melanoma diagnosis.

“No test is perfect, and this applies to PLA, even if you get a double-positive or double-negative test result,” Dr. Kim said. “You want to make sure that patients are aware of false positives and negatives. However, PLA could be an additional piece of data to inform your decision to proceed with biopsy on select borderline suspicious pigmented lesions. More studies are needed to better understand the approach to single- and double-positive PLA results.”

The PLA kit contains adhesive patches and supplies and a FedEx envelope for return to DermTech, the test’s manufacturer, for processing. The patches can be applied to lesions at least 4 mm in diameter; multiple kits are recommended for those greater than 16 mm in diameter. The test is not validated for lesions located on mucous membranes, palms, soles, nails, or on ulcerated or bleeding lesions, nor for those that have been previously biopsied. It is also not validated for use in pediatric patients or in those with skin types IV or higher. Results are returned in 2-3 days. If insurance does not cover the test, the cost to the patient is approximately $50 per lesion or a maximum of $150, according to Dr. Kim.
 

Use in clinical practice

In Dr. Kim’s clinical experience, the PLA can be considered for suspicious pigmented lesions on cosmetically sensitive areas and for suspicious lesions in areas difficult to biopsy or excise. For example, she discussed the case of a 72-year-old woman with a family history of melanoma, who presented to her clinic with a longstanding pigmented lesion on her right upper and lower eyelids that had previously been treated with laser. She had undergone multiple prior biopsies over 12 years, which caused mild to moderate atypical melanocytic proliferation. The PLA result was double negative for PRAME and LINC in her upper and lower eyelid, “which provided reassurance to the patient,” Dr. Kim said. The patient continues to be followed closely for any clinical changes.

Another patient, a 67-year-old woman, was referred to Dr. Kim from out of state for a teledermatology visit early in the COVID-19 pandemic. The patient had a lesion on her right calf that was hard, raised, and pink, did not resemble other lesions on her body, and had been present for a few weeks. “Her husband had recently passed away from brain cancer and she was very concerned about melanoma,” Dr. Kim recalled. “She lived alone, and the adult son was with her during the teledermatology call to assist. The patient asked about the PLA test, and given her difficulty going to a medical office at the time, we agreed to help her with this test.” The patient and her son arranged another teledermatology visit with Dr. Kim after receiving the kit in the mail from DermTech, and Dr. Kim coached them on how to properly administer the test. The results came back as PRAME negative and LINC positive. A biopsy with a local provider was recommended and the pathology results showed an inflamed seborrheic keratosis.

“This case exemplifies a false-positive result. We should be sure to make patients aware of this possibility,” Dr. Kim said.

Incorporating PLA into clinical practice requires certain workflow considerations, with paperwork to fill out in addition to performing the adhesive test, collection of insurance information, mailing the kit via FedEx, retrieving the results, and following up with the patient, said Dr. Kim. “For select borderline pigmented lesions, I discuss the rationale of the test with patients, the possibility of false-positive and false-negative results and the need to return for a biopsy when there is positive result. Clinical follow-up is recommended for negative results. There is also the possibility of charge to the patient if the test is not covered by their insurance.”
 

Skin biopsy still the gold standard

Despite the availability of the PLA as an assessment tool, Dr. Kim emphasized that skin biopsy remains the gold standard for diagnosing melanoma. “Future prospective randomized clinical trials are needed to examine the role of genetic expression profiling in staging and managing patients,” she said.

In 2019, she and her colleagues surveyed 42 pigmented lesion experts in the United States about why they ordered one of three molecular tests on the market or not and how results affected patient treatment. The proportion of clinicians who ordered the tests ranged from 21% to 29%. The top 2 reasons respondents chose for not ordering the PLA test specifically were: “Feel that further validation studies are necessary” (20%) and “do not feel it would be useful in my practice” (18%).

Results of a larger follow-up survey on usage patterns of PLA of both pigmented lesion experts and general clinicians on this topic are expected to be published shortly.

Dr. Kim reported having no disclosures related to her presentation.

BOSTON – Although skin biopsy remains the gold standard for diagnosing early-stage melanoma, advances in genetic expression profiling are helping dermatologists provide a nuanced approach to managing suspicious lesions.

One such test, the Pigmented Lesional Assay (PLA) uses adhesive patches applied to lesions of concern at the bedside to extract RNA from the stratum corneum to help determine the risk for melanoma.

At the annual meeting of the American Academy of Dermatology, Caroline C. Kim, MD, director of melanoma and pigmented lesion clinics at Newton Wellesley Dermatology, Wellesley Hills, Mass., and Tufts Medical Center, Boston, spoke about the PLA, which uses genetic expression profiling to measure the expression level of specific genes that are associated with melanoma: PRAME (preferentially expressed antigen in melanoma) and LINC00518 (LINC). There are four possible results of the test: Aberrant expression of both LINC and PRAME (high risk); aberrant expression of a single gene (moderate risk); aberrant expression of neither gene (low risk); or inconclusive.

Validation data have shown a sensitivity of 91% and a specificity of 69% for the PLA, with a 99% negative predictive value; so a lesion that tested negative by PLA has a less than 1% chance of being melanoma. In addition, a study published in 2020 found that the addition of TERT (telomerase reverse transcriptase) mutation analyses increased the sensitivity of the PLA to 97%.

While the high negative predictive value is helpful to consider in clinical scenarios to rule-out melanoma for borderline lesions, one must consider the positive predictive value as well and how this may impact clinical care, Dr. Kim said. In a study examining outcomes of 381 lesions, 51 were PLA positive (single or double) and were biopsied, of which 19 (37%) revealed a melanoma diagnosis. In a large U.S. registry study of 3,418 lesions, 324 lesions that were PLA double positive were biopsied, with 18.7% revealing a melanoma diagnosis.

“No test is perfect, and this applies to PLA, even if you get a double-positive or double-negative test result,” Dr. Kim said. “You want to make sure that patients are aware of false positives and negatives. However, PLA could be an additional piece of data to inform your decision to proceed with biopsy on select borderline suspicious pigmented lesions. More studies are needed to better understand the approach to single- and double-positive PLA results.”

The PLA kit contains adhesive patches and supplies and a FedEx envelope for return to DermTech, the test’s manufacturer, for processing. The patches can be applied to lesions at least 4 mm in diameter; multiple kits are recommended for those greater than 16 mm in diameter. The test is not validated for lesions located on mucous membranes, palms, soles, nails, or on ulcerated or bleeding lesions, nor for those that have been previously biopsied. It is also not validated for use in pediatric patients or in those with skin types IV or higher. Results are returned in 2-3 days. If insurance does not cover the test, the cost to the patient is approximately $50 per lesion or a maximum of $150, according to Dr. Kim.
 

Use in clinical practice

In Dr. Kim’s clinical experience, the PLA can be considered for suspicious pigmented lesions on cosmetically sensitive areas and for suspicious lesions in areas difficult to biopsy or excise. For example, she discussed the case of a 72-year-old woman with a family history of melanoma, who presented to her clinic with a longstanding pigmented lesion on her right upper and lower eyelids that had previously been treated with laser. She had undergone multiple prior biopsies over 12 years, which caused mild to moderate atypical melanocytic proliferation. The PLA result was double negative for PRAME and LINC in her upper and lower eyelid, “which provided reassurance to the patient,” Dr. Kim said. The patient continues to be followed closely for any clinical changes.

Another patient, a 67-year-old woman, was referred to Dr. Kim from out of state for a teledermatology visit early in the COVID-19 pandemic. The patient had a lesion on her right calf that was hard, raised, and pink, did not resemble other lesions on her body, and had been present for a few weeks. “Her husband had recently passed away from brain cancer and she was very concerned about melanoma,” Dr. Kim recalled. “She lived alone, and the adult son was with her during the teledermatology call to assist. The patient asked about the PLA test, and given her difficulty going to a medical office at the time, we agreed to help her with this test.” The patient and her son arranged another teledermatology visit with Dr. Kim after receiving the kit in the mail from DermTech, and Dr. Kim coached them on how to properly administer the test. The results came back as PRAME negative and LINC positive. A biopsy with a local provider was recommended and the pathology results showed an inflamed seborrheic keratosis.

“This case exemplifies a false-positive result. We should be sure to make patients aware of this possibility,” Dr. Kim said.

Incorporating PLA into clinical practice requires certain workflow considerations, with paperwork to fill out in addition to performing the adhesive test, collection of insurance information, mailing the kit via FedEx, retrieving the results, and following up with the patient, said Dr. Kim. “For select borderline pigmented lesions, I discuss the rationale of the test with patients, the possibility of false-positive and false-negative results and the need to return for a biopsy when there is positive result. Clinical follow-up is recommended for negative results. There is also the possibility of charge to the patient if the test is not covered by their insurance.”
 

Skin biopsy still the gold standard

Despite the availability of the PLA as an assessment tool, Dr. Kim emphasized that skin biopsy remains the gold standard for diagnosing melanoma. “Future prospective randomized clinical trials are needed to examine the role of genetic expression profiling in staging and managing patients,” she said.

In 2019, she and her colleagues surveyed 42 pigmented lesion experts in the United States about why they ordered one of three molecular tests on the market or not and how results affected patient treatment. The proportion of clinicians who ordered the tests ranged from 21% to 29%. The top 2 reasons respondents chose for not ordering the PLA test specifically were: “Feel that further validation studies are necessary” (20%) and “do not feel it would be useful in my practice” (18%).

Results of a larger follow-up survey on usage patterns of PLA of both pigmented lesion experts and general clinicians on this topic are expected to be published shortly.

Dr. Kim reported having no disclosures related to her presentation.

BOSTON – Although skin biopsy remains the gold standard for diagnosing early-stage melanoma, advances in genetic expression profiling are helping dermatologists provide a nuanced approach to managing suspicious lesions.

One such test, the Pigmented Lesional Assay (PLA) uses adhesive patches applied to lesions of concern at the bedside to extract RNA from the stratum corneum to help determine the risk for melanoma.

At the annual meeting of the American Academy of Dermatology, Caroline C. Kim, MD, director of melanoma and pigmented lesion clinics at Newton Wellesley Dermatology, Wellesley Hills, Mass., and Tufts Medical Center, Boston, spoke about the PLA, which uses genetic expression profiling to measure the expression level of specific genes that are associated with melanoma: PRAME (preferentially expressed antigen in melanoma) and LINC00518 (LINC). There are four possible results of the test: Aberrant expression of both LINC and PRAME (high risk); aberrant expression of a single gene (moderate risk); aberrant expression of neither gene (low risk); or inconclusive.

Validation data have shown a sensitivity of 91% and a specificity of 69% for the PLA, with a 99% negative predictive value; so a lesion that tested negative by PLA has a less than 1% chance of being melanoma. In addition, a study published in 2020 found that the addition of TERT (telomerase reverse transcriptase) mutation analyses increased the sensitivity of the PLA to 97%.

While the high negative predictive value is helpful to consider in clinical scenarios to rule-out melanoma for borderline lesions, one must consider the positive predictive value as well and how this may impact clinical care, Dr. Kim said. In a study examining outcomes of 381 lesions, 51 were PLA positive (single or double) and were biopsied, of which 19 (37%) revealed a melanoma diagnosis. In a large U.S. registry study of 3,418 lesions, 324 lesions that were PLA double positive were biopsied, with 18.7% revealing a melanoma diagnosis.

“No test is perfect, and this applies to PLA, even if you get a double-positive or double-negative test result,” Dr. Kim said. “You want to make sure that patients are aware of false positives and negatives. However, PLA could be an additional piece of data to inform your decision to proceed with biopsy on select borderline suspicious pigmented lesions. More studies are needed to better understand the approach to single- and double-positive PLA results.”

The PLA kit contains adhesive patches and supplies and a FedEx envelope for return to DermTech, the test’s manufacturer, for processing. The patches can be applied to lesions at least 4 mm in diameter; multiple kits are recommended for those greater than 16 mm in diameter. The test is not validated for lesions located on mucous membranes, palms, soles, nails, or on ulcerated or bleeding lesions, nor for those that have been previously biopsied. It is also not validated for use in pediatric patients or in those with skin types IV or higher. Results are returned in 2-3 days. If insurance does not cover the test, the cost to the patient is approximately $50 per lesion or a maximum of $150, according to Dr. Kim.
 

Use in clinical practice

In Dr. Kim’s clinical experience, the PLA can be considered for suspicious pigmented lesions on cosmetically sensitive areas and for suspicious lesions in areas difficult to biopsy or excise. For example, she discussed the case of a 72-year-old woman with a family history of melanoma, who presented to her clinic with a longstanding pigmented lesion on her right upper and lower eyelids that had previously been treated with laser. She had undergone multiple prior biopsies over 12 years, which caused mild to moderate atypical melanocytic proliferation. The PLA result was double negative for PRAME and LINC in her upper and lower eyelid, “which provided reassurance to the patient,” Dr. Kim said. The patient continues to be followed closely for any clinical changes.

Another patient, a 67-year-old woman, was referred to Dr. Kim from out of state for a teledermatology visit early in the COVID-19 pandemic. The patient had a lesion on her right calf that was hard, raised, and pink, did not resemble other lesions on her body, and had been present for a few weeks. “Her husband had recently passed away from brain cancer and she was very concerned about melanoma,” Dr. Kim recalled. “She lived alone, and the adult son was with her during the teledermatology call to assist. The patient asked about the PLA test, and given her difficulty going to a medical office at the time, we agreed to help her with this test.” The patient and her son arranged another teledermatology visit with Dr. Kim after receiving the kit in the mail from DermTech, and Dr. Kim coached them on how to properly administer the test. The results came back as PRAME negative and LINC positive. A biopsy with a local provider was recommended and the pathology results showed an inflamed seborrheic keratosis.

“This case exemplifies a false-positive result. We should be sure to make patients aware of this possibility,” Dr. Kim said.

Incorporating PLA into clinical practice requires certain workflow considerations, with paperwork to fill out in addition to performing the adhesive test, collection of insurance information, mailing the kit via FedEx, retrieving the results, and following up with the patient, said Dr. Kim. “For select borderline pigmented lesions, I discuss the rationale of the test with patients, the possibility of false-positive and false-negative results and the need to return for a biopsy when there is positive result. Clinical follow-up is recommended for negative results. There is also the possibility of charge to the patient if the test is not covered by their insurance.”
 

Skin biopsy still the gold standard

Despite the availability of the PLA as an assessment tool, Dr. Kim emphasized that skin biopsy remains the gold standard for diagnosing melanoma. “Future prospective randomized clinical trials are needed to examine the role of genetic expression profiling in staging and managing patients,” she said.

In 2019, she and her colleagues surveyed 42 pigmented lesion experts in the United States about why they ordered one of three molecular tests on the market or not and how results affected patient treatment. The proportion of clinicians who ordered the tests ranged from 21% to 29%. The top 2 reasons respondents chose for not ordering the PLA test specifically were: “Feel that further validation studies are necessary” (20%) and “do not feel it would be useful in my practice” (18%).

Results of a larger follow-up survey on usage patterns of PLA of both pigmented lesion experts and general clinicians on this topic are expected to be published shortly.

Dr. Kim reported having no disclosures related to her presentation.