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The Diagnosis: Acquired Lymphangioma Circumscriptum

A skin biopsy of the plaque on the right labium majus showed a proliferation of well-formed, dilated lymphatic vessels lined by benign-appearing endothelial cells in the papillary dermis (Figure). These findings were consistent with a diagnosis of acquired lymphangioma circumscriptum (ALC) in the setting of severe hidradenitis suppurativa (HS).

Image courtesy of Alicia Schnebelen, MD (Dallas, Texas).

Acquired lymphangioma circumscriptum (also known as acquired lymphangiectasia or secondary lymphangioma¹) is a rare skin finding resulting from chronic lymphatic obstruction that leads to dilated lymphatic vessels within the dermis.^2,3 There also is a distinct congenital form of lymphangioma circumscriptum caused by lymphatic malformations present at birth.^2,4 Acquired lymphangioma circumscriptum of the vulva is a rare phenomenon.³ Identified causes include radiation or surgery for carcinoma, solid gynecologic tumors, lymphadenectomy, Crohn disease, and tuberculosis and other infections, all of which can disrupt normal lymphatics to cause ALC.^2-4 Hidradenitis suppurativa is not a widely recognized cause of ALC; however, this phenomenon is reported in the literature. A long-standing history of severe HS complicated by lymphedema seems to precede the development of ALC in the reported cases, as in our patient.^5-7

Acquired lymphangioma circumscriptum of the vulva can appear in women of all ages as frog spawn or cobblestone papules or vesicles, sometimes with a hyperkeratotic or verrucous appearance.^2,4 Associated symptoms include serous drainage, edema, pruritus, and discomfort. The lesions may become eroded, which can predispose patients to secondary infections.^1,2 Acquired lymphangioma circumscriptum of the vulva can be difficult to diagnose, as the time interval between the initial cause and the appearance of skin findings can be years, leading to the misdiagnosis of ALC as other similar-appearing genital skin conditions such as squamous cell carcinoma or condyloma.^4,8 When misidentified as an infection, diagnosis can lead to substantial distress, abstinence from sexual activity, and unnecessary and painful treatments.

Skin biopsy is helpful in distinguishing ALC from other differential diagnoses such as condylomata acuminata, squamous cell carcinoma, and condyloma lata. Histopathology in ALC is notable for dilated lymphatic vessels filled with hypocellular fluid and lined with endothelial cells in the superficial dermis; the epidermis can appear hyperplastic, hyperkeratotic, or eroded.^3-5,9 These lymphatic vessels stain positively for CD31 and D2-40, markers for endothelial cells and lymphatic endothelium, respectively, and negative for CD34, a marker for vascular endothelium.^3,4,9 Features suggestive of condylomata acuminata such as rounded parakeratosis, hypergranulosis, and vacuolated keratinocytes⁹ are not present. The giant condyloma of Buschke-Löwenstein, a clinical variant of verrucous squamous cell carcinoma, also can present as a warty ulcerated papule or plaque in the genital region, but the characteristic rounded eosinophilic keratinocytes pushing down into the dermis⁹ are not seen in ALC. Secondary syphilis is associated with condyloma lata, which are verrucous or fleshy-appearing papules often coalescing into plaques located in the anogenital region. Pathologic features of secondary syphilis include vacuolar interface dermatitis and acanthosis with long slender rete ridges.⁹ Squamous cell carcinoma, which can arise from inflammation associated with long-standing HS, must be ruled out, as it is associated with a high risk of mortality in patients with HS.¹⁰

It is noteworthy to recognize the various, often confusing nomenclature used to describe cutaneous lymphatic conditions. The terms acquired lymphangioma circumscriptum, secondary lymphangioma, and lymphangiectasia are used interchangeably to describe dilated lymphatic vessels in the skin.¹ The term atypical vascular lesion refers to lymphectasias of the skin of the breast due to prior radiation therapy most often used in the treatment of breast carcinoma; clinically, these present as red-brown or flesh-colored papules or telangiectatic plaques on the breast.^11,12 Lymphedema also may occur alongside atypical vascular lesions, as prior radiation or surgical lymph node dissection can predispose patients to impaired lymphatic drainage.¹³ The lymphatic histopathologic subtype of atypical vascular lesions may appear similar to ALC; however, the vascular subtype will demonstrate collections of capillary-sized vessels and extravasated erythrocytes.^11,12 Unlike ALC, the benign nature of atypical vascular lesions has been questioned, as they may be associated with a small risk for progression to angiosarcoma.^11-13 It also is important to distinguish ALC from lymphangiomatosis, a generalized lymphatic anomaly that is characterized by extensive lymphatic malformations involving numerous internal organs, including the lungs and gastrointestinal tract. This condition is associated with notable morbidity and mortality.¹³

Although the suffix of the term lymphangioma suggests a neoplastic process, ALC is not a neoplasm and can be managed expectantly in many cases.^2,3,8 However, due to cosmetic appearance, pain, discomfort, and recurrent bacterial superinfections, many patients pursue treatment. Treatment options for ALC include sclerotherapy, electrocautery, radiofrequency or carbon dioxide laser ablation, and excision, though recurrence can arise.^3-5,7,8 Our patient elected to manage her asymptomatic ALC expectantly.

The Diagnosis: Acquired Lymphangioma Circumscriptum

A skin biopsy of the plaque on the right labium majus showed a proliferation of well-formed, dilated lymphatic vessels lined by benign-appearing endothelial cells in the papillary dermis (Figure). These findings were consistent with a diagnosis of acquired lymphangioma circumscriptum (ALC) in the setting of severe hidradenitis suppurativa (HS).

Image courtesy of Alicia Schnebelen, MD (Dallas, Texas).

Acquired lymphangioma circumscriptum (also known as acquired lymphangiectasia or secondary lymphangioma¹) is a rare skin finding resulting from chronic lymphatic obstruction that leads to dilated lymphatic vessels within the dermis.^2,3 There also is a distinct congenital form of lymphangioma circumscriptum caused by lymphatic malformations present at birth.^2,4 Acquired lymphangioma circumscriptum of the vulva is a rare phenomenon.³ Identified causes include radiation or surgery for carcinoma, solid gynecologic tumors, lymphadenectomy, Crohn disease, and tuberculosis and other infections, all of which can disrupt normal lymphatics to cause ALC.^2-4 Hidradenitis suppurativa is not a widely recognized cause of ALC; however, this phenomenon is reported in the literature. A long-standing history of severe HS complicated by lymphedema seems to precede the development of ALC in the reported cases, as in our patient.^5-7

Acquired lymphangioma circumscriptum of the vulva can appear in women of all ages as frog spawn or cobblestone papules or vesicles, sometimes with a hyperkeratotic or verrucous appearance.^2,4 Associated symptoms include serous drainage, edema, pruritus, and discomfort. The lesions may become eroded, which can predispose patients to secondary infections.^1,2 Acquired lymphangioma circumscriptum of the vulva can be difficult to diagnose, as the time interval between the initial cause and the appearance of skin findings can be years, leading to the misdiagnosis of ALC as other similar-appearing genital skin conditions such as squamous cell carcinoma or condyloma.^4,8 When misidentified as an infection, diagnosis can lead to substantial distress, abstinence from sexual activity, and unnecessary and painful treatments.

Skin biopsy is helpful in distinguishing ALC from other differential diagnoses such as condylomata acuminata, squamous cell carcinoma, and condyloma lata. Histopathology in ALC is notable for dilated lymphatic vessels filled with hypocellular fluid and lined with endothelial cells in the superficial dermis; the epidermis can appear hyperplastic, hyperkeratotic, or eroded.^3-5,9 These lymphatic vessels stain positively for CD31 and D2-40, markers for endothelial cells and lymphatic endothelium, respectively, and negative for CD34, a marker for vascular endothelium.^3,4,9 Features suggestive of condylomata acuminata such as rounded parakeratosis, hypergranulosis, and vacuolated keratinocytes⁹ are not present. The giant condyloma of Buschke-Löwenstein, a clinical variant of verrucous squamous cell carcinoma, also can present as a warty ulcerated papule or plaque in the genital region, but the characteristic rounded eosinophilic keratinocytes pushing down into the dermis⁹ are not seen in ALC. Secondary syphilis is associated with condyloma lata, which are verrucous or fleshy-appearing papules often coalescing into plaques located in the anogenital region. Pathologic features of secondary syphilis include vacuolar interface dermatitis and acanthosis with long slender rete ridges.⁹ Squamous cell carcinoma, which can arise from inflammation associated with long-standing HS, must be ruled out, as it is associated with a high risk of mortality in patients with HS.¹⁰

It is noteworthy to recognize the various, often confusing nomenclature used to describe cutaneous lymphatic conditions. The terms acquired lymphangioma circumscriptum, secondary lymphangioma, and lymphangiectasia are used interchangeably to describe dilated lymphatic vessels in the skin.¹ The term atypical vascular lesion refers to lymphectasias of the skin of the breast due to prior radiation therapy most often used in the treatment of breast carcinoma; clinically, these present as red-brown or flesh-colored papules or telangiectatic plaques on the breast.^11,12 Lymphedema also may occur alongside atypical vascular lesions, as prior radiation or surgical lymph node dissection can predispose patients to impaired lymphatic drainage.¹³ The lymphatic histopathologic subtype of atypical vascular lesions may appear similar to ALC; however, the vascular subtype will demonstrate collections of capillary-sized vessels and extravasated erythrocytes.^11,12 Unlike ALC, the benign nature of atypical vascular lesions has been questioned, as they may be associated with a small risk for progression to angiosarcoma.^11-13 It also is important to distinguish ALC from lymphangiomatosis, a generalized lymphatic anomaly that is characterized by extensive lymphatic malformations involving numerous internal organs, including the lungs and gastrointestinal tract. This condition is associated with notable morbidity and mortality.¹³

Although the suffix of the term lymphangioma suggests a neoplastic process, ALC is not a neoplasm and can be managed expectantly in many cases.^2,3,8 However, due to cosmetic appearance, pain, discomfort, and recurrent bacterial superinfections, many patients pursue treatment. Treatment options for ALC include sclerotherapy, electrocautery, radiofrequency or carbon dioxide laser ablation, and excision, though recurrence can arise.^3-5,7,8 Our patient elected to manage her asymptomatic ALC expectantly.

The Diagnosis: Acquired Lymphangioma Circumscriptum

A skin biopsy of the plaque on the right labium majus showed a proliferation of well-formed, dilated lymphatic vessels lined by benign-appearing endothelial cells in the papillary dermis (Figure). These findings were consistent with a diagnosis of acquired lymphangioma circumscriptum (ALC) in the setting of severe hidradenitis suppurativa (HS).

Image courtesy of Alicia Schnebelen, MD (Dallas, Texas).

Acquired lymphangioma circumscriptum (also known as acquired lymphangiectasia or secondary lymphangioma¹) is a rare skin finding resulting from chronic lymphatic obstruction that leads to dilated lymphatic vessels within the dermis.^2,3 There also is a distinct congenital form of lymphangioma circumscriptum caused by lymphatic malformations present at birth.^2,4 Acquired lymphangioma circumscriptum of the vulva is a rare phenomenon.³ Identified causes include radiation or surgery for carcinoma, solid gynecologic tumors, lymphadenectomy, Crohn disease, and tuberculosis and other infections, all of which can disrupt normal lymphatics to cause ALC.^2-4 Hidradenitis suppurativa is not a widely recognized cause of ALC; however, this phenomenon is reported in the literature. A long-standing history of severe HS complicated by lymphedema seems to precede the development of ALC in the reported cases, as in our patient.^5-7

Acquired lymphangioma circumscriptum of the vulva can appear in women of all ages as frog spawn or cobblestone papules or vesicles, sometimes with a hyperkeratotic or verrucous appearance.^2,4 Associated symptoms include serous drainage, edema, pruritus, and discomfort. The lesions may become eroded, which can predispose patients to secondary infections.^1,2 Acquired lymphangioma circumscriptum of the vulva can be difficult to diagnose, as the time interval between the initial cause and the appearance of skin findings can be years, leading to the misdiagnosis of ALC as other similar-appearing genital skin conditions such as squamous cell carcinoma or condyloma.^4,8 When misidentified as an infection, diagnosis can lead to substantial distress, abstinence from sexual activity, and unnecessary and painful treatments.

Skin biopsy is helpful in distinguishing ALC from other differential diagnoses such as condylomata acuminata, squamous cell carcinoma, and condyloma lata. Histopathology in ALC is notable for dilated lymphatic vessels filled with hypocellular fluid and lined with endothelial cells in the superficial dermis; the epidermis can appear hyperplastic, hyperkeratotic, or eroded.^3-5,9 These lymphatic vessels stain positively for CD31 and D2-40, markers for endothelial cells and lymphatic endothelium, respectively, and negative for CD34, a marker for vascular endothelium.^3,4,9 Features suggestive of condylomata acuminata such as rounded parakeratosis, hypergranulosis, and vacuolated keratinocytes⁹ are not present. The giant condyloma of Buschke-Löwenstein, a clinical variant of verrucous squamous cell carcinoma, also can present as a warty ulcerated papule or plaque in the genital region, but the characteristic rounded eosinophilic keratinocytes pushing down into the dermis⁹ are not seen in ALC. Secondary syphilis is associated with condyloma lata, which are verrucous or fleshy-appearing papules often coalescing into plaques located in the anogenital region. Pathologic features of secondary syphilis include vacuolar interface dermatitis and acanthosis with long slender rete ridges.⁹ Squamous cell carcinoma, which can arise from inflammation associated with long-standing HS, must be ruled out, as it is associated with a high risk of mortality in patients with HS.¹⁰

It is noteworthy to recognize the various, often confusing nomenclature used to describe cutaneous lymphatic conditions. The terms acquired lymphangioma circumscriptum, secondary lymphangioma, and lymphangiectasia are used interchangeably to describe dilated lymphatic vessels in the skin.¹ The term atypical vascular lesion refers to lymphectasias of the skin of the breast due to prior radiation therapy most often used in the treatment of breast carcinoma; clinically, these present as red-brown or flesh-colored papules or telangiectatic plaques on the breast.^11,12 Lymphedema also may occur alongside atypical vascular lesions, as prior radiation or surgical lymph node dissection can predispose patients to impaired lymphatic drainage.¹³ The lymphatic histopathologic subtype of atypical vascular lesions may appear similar to ALC; however, the vascular subtype will demonstrate collections of capillary-sized vessels and extravasated erythrocytes.^11,12 Unlike ALC, the benign nature of atypical vascular lesions has been questioned, as they may be associated with a small risk for progression to angiosarcoma.^11-13 It also is important to distinguish ALC from lymphangiomatosis, a generalized lymphatic anomaly that is characterized by extensive lymphatic malformations involving numerous internal organs, including the lungs and gastrointestinal tract. This condition is associated with notable morbidity and mortality.¹³

Although the suffix of the term lymphangioma suggests a neoplastic process, ALC is not a neoplasm and can be managed expectantly in many cases.^2,3,8 However, due to cosmetic appearance, pain, discomfort, and recurrent bacterial superinfections, many patients pursue treatment. Treatment options for ALC include sclerotherapy, electrocautery, radiofrequency or carbon dioxide laser ablation, and excision, though recurrence can arise.^3-5,7,8 Our patient elected to manage her asymptomatic ALC expectantly.

The Diagnosis: Odontogenic Cutaneous Sinus Tract

In our patient, panoramic radiography showed a radiolucency in the periapex of the mandibular first molar (Figure 1). Ultrasonography depicted a hypoechoic band that originated from the cutaneous lesion and extended through the subcutaneous tissue to the defective alveolar bone, suggesting odontogenic inflammation (Figure 2).¹ The infected pulp was removed, and the purulent nodules then disappeared.

The dental etiology of odontogenic cutaneous sinus tracts can be confirmed by panoramic radiography and ultrasonography. The odontogenic sinus path can be clearly observed via radiography by injecting or inserting a radiopaque substance into the sinus tract.² Effective treatment of the diseased tooth is removal of the infected pulp, performance of a root canal to eliminate infection, closure and filling of the root canal, and repair of the crown. Once the source of infection is eliminated, the sinus typically subsides within 2 weeks. When residual skin retreats or scars are present, cosmetic surgery can be performed to improve the appearance.^3,4

Odontogenic cutaneous sinus tracts usually are caused by a route of drainage from a chronic apical abscess. They follow a path of least resistance through the alveolar bone and periosteum, spreading into the surrounding soft tissues. With the formation of abscesses, sinus tracts will erupt intraorally or cutaneously, depending on the relationship of the posterior tooth apices to the mandibular attachments of the mylohyoid and buccinator muscles and the maxillary attachment of the buccinator.^2,5 Clinically, cutaneous lesions present as nodules, cysts, or dimples that have attached to deep tissues through the sinus tract. Half of patients may have no dental symptoms and often are misdiagnosed with nonodontogenic lesions. Subsequent improper treatments, such as repeated use of antibiotics, multiple biopsies, surgical excision, and chemotherapy, often are repeated and ineffective.⁶ The most common cause of chronic cutaneous sinus tracts in the face and neck is a chronically draining dental infection.^2,5 A thorough history is necessary when odontogenic cutaneous sinuses are suspected. Toothache before the development of the sinus tract is an important diagnostic clue.

Pyogenic granuloma, syringocystadenoma papilliferum, osteomyelitis, infected epidermoid cyst, actinomycoses, and salivary gland fistula also should be considered in the differential diagnosis.^7-10 Pyogenic granuloma (also known as lobular capillary hemangioma) is a benign overgrowth of capillaries showing a vascular phenotype that usually occurs as a response to different stimulating factors such as local stimuli, trauma, or hormonal factors. Clinically, pyogenic granuloma presents as a red, solitary, painless nodule on the face or distal extremities.^11,12 Syringocystadenoma papilliferum is a benign adnexal proliferation with apocrine differentiation that usually presents as a hairless papillomatous plaque or nodule measuring 1 to 4 cm in diameter and often is first noted at birth or during early childhood.⁷ Osteomyelitis is progressive inflammation of the periosteum and bone marrow that rapidly breaks through the periosteum and spreads to surrounding areas. The mandible is the most susceptible bone for facial osteomyelitis.⁸ Epidermoid cysts are formed by the proliferation of epidermal cells within a circumscribed dermal space. Infection of the cysts is characterized by redness, swelling, heat, and pain. As the infection progresses, suppurative inflammation develops, leading to local liquefaction and abscesses.⁹

This case was initially misdiagnosed as infectious skin lesions by outside clinicians. Multiple surgical treatments and long-term antibiotic therapy were attempted before the correct diagnosis was made. The clinical diagnosis of odontogenic cutaneous sinus tracts is challenging due to the variety of affected sites and clinical signs. Ultrasonography should be performed as early as possible to identify the disease and avoid unnecessary surgery. For appropriate dental therapy, close liaison with the stomatology department is warranted.

The Diagnosis: Odontogenic Cutaneous Sinus Tract

In our patient, panoramic radiography showed a radiolucency in the periapex of the mandibular first molar (Figure 1). Ultrasonography depicted a hypoechoic band that originated from the cutaneous lesion and extended through the subcutaneous tissue to the defective alveolar bone, suggesting odontogenic inflammation (Figure 2).¹ The infected pulp was removed, and the purulent nodules then disappeared.

The dental etiology of odontogenic cutaneous sinus tracts can be confirmed by panoramic radiography and ultrasonography. The odontogenic sinus path can be clearly observed via radiography by injecting or inserting a radiopaque substance into the sinus tract.² Effective treatment of the diseased tooth is removal of the infected pulp, performance of a root canal to eliminate infection, closure and filling of the root canal, and repair of the crown. Once the source of infection is eliminated, the sinus typically subsides within 2 weeks. When residual skin retreats or scars are present, cosmetic surgery can be performed to improve the appearance.^3,4

Odontogenic cutaneous sinus tracts usually are caused by a route of drainage from a chronic apical abscess. They follow a path of least resistance through the alveolar bone and periosteum, spreading into the surrounding soft tissues. With the formation of abscesses, sinus tracts will erupt intraorally or cutaneously, depending on the relationship of the posterior tooth apices to the mandibular attachments of the mylohyoid and buccinator muscles and the maxillary attachment of the buccinator.^2,5 Clinically, cutaneous lesions present as nodules, cysts, or dimples that have attached to deep tissues through the sinus tract. Half of patients may have no dental symptoms and often are misdiagnosed with nonodontogenic lesions. Subsequent improper treatments, such as repeated use of antibiotics, multiple biopsies, surgical excision, and chemotherapy, often are repeated and ineffective.⁶ The most common cause of chronic cutaneous sinus tracts in the face and neck is a chronically draining dental infection.^2,5 A thorough history is necessary when odontogenic cutaneous sinuses are suspected. Toothache before the development of the sinus tract is an important diagnostic clue.

Pyogenic granuloma, syringocystadenoma papilliferum, osteomyelitis, infected epidermoid cyst, actinomycoses, and salivary gland fistula also should be considered in the differential diagnosis.^7-10 Pyogenic granuloma (also known as lobular capillary hemangioma) is a benign overgrowth of capillaries showing a vascular phenotype that usually occurs as a response to different stimulating factors such as local stimuli, trauma, or hormonal factors. Clinically, pyogenic granuloma presents as a red, solitary, painless nodule on the face or distal extremities.^11,12 Syringocystadenoma papilliferum is a benign adnexal proliferation with apocrine differentiation that usually presents as a hairless papillomatous plaque or nodule measuring 1 to 4 cm in diameter and often is first noted at birth or during early childhood.⁷ Osteomyelitis is progressive inflammation of the periosteum and bone marrow that rapidly breaks through the periosteum and spreads to surrounding areas. The mandible is the most susceptible bone for facial osteomyelitis.⁸ Epidermoid cysts are formed by the proliferation of epidermal cells within a circumscribed dermal space. Infection of the cysts is characterized by redness, swelling, heat, and pain. As the infection progresses, suppurative inflammation develops, leading to local liquefaction and abscesses.⁹

This case was initially misdiagnosed as infectious skin lesions by outside clinicians. Multiple surgical treatments and long-term antibiotic therapy were attempted before the correct diagnosis was made. The clinical diagnosis of odontogenic cutaneous sinus tracts is challenging due to the variety of affected sites and clinical signs. Ultrasonography should be performed as early as possible to identify the disease and avoid unnecessary surgery. For appropriate dental therapy, close liaison with the stomatology department is warranted.

The Diagnosis: Odontogenic Cutaneous Sinus Tract

In our patient, panoramic radiography showed a radiolucency in the periapex of the mandibular first molar (Figure 1). Ultrasonography depicted a hypoechoic band that originated from the cutaneous lesion and extended through the subcutaneous tissue to the defective alveolar bone, suggesting odontogenic inflammation (Figure 2).¹ The infected pulp was removed, and the purulent nodules then disappeared.

The dental etiology of odontogenic cutaneous sinus tracts can be confirmed by panoramic radiography and ultrasonography. The odontogenic sinus path can be clearly observed via radiography by injecting or inserting a radiopaque substance into the sinus tract.² Effective treatment of the diseased tooth is removal of the infected pulp, performance of a root canal to eliminate infection, closure and filling of the root canal, and repair of the crown. Once the source of infection is eliminated, the sinus typically subsides within 2 weeks. When residual skin retreats or scars are present, cosmetic surgery can be performed to improve the appearance.^3,4

Odontogenic cutaneous sinus tracts usually are caused by a route of drainage from a chronic apical abscess. They follow a path of least resistance through the alveolar bone and periosteum, spreading into the surrounding soft tissues. With the formation of abscesses, sinus tracts will erupt intraorally or cutaneously, depending on the relationship of the posterior tooth apices to the mandibular attachments of the mylohyoid and buccinator muscles and the maxillary attachment of the buccinator.^2,5 Clinically, cutaneous lesions present as nodules, cysts, or dimples that have attached to deep tissues through the sinus tract. Half of patients may have no dental symptoms and often are misdiagnosed with nonodontogenic lesions. Subsequent improper treatments, such as repeated use of antibiotics, multiple biopsies, surgical excision, and chemotherapy, often are repeated and ineffective.⁶ The most common cause of chronic cutaneous sinus tracts in the face and neck is a chronically draining dental infection.^2,5 A thorough history is necessary when odontogenic cutaneous sinuses are suspected. Toothache before the development of the sinus tract is an important diagnostic clue.

Pyogenic granuloma, syringocystadenoma papilliferum, osteomyelitis, infected epidermoid cyst, actinomycoses, and salivary gland fistula also should be considered in the differential diagnosis.^7-10 Pyogenic granuloma (also known as lobular capillary hemangioma) is a benign overgrowth of capillaries showing a vascular phenotype that usually occurs as a response to different stimulating factors such as local stimuli, trauma, or hormonal factors. Clinically, pyogenic granuloma presents as a red, solitary, painless nodule on the face or distal extremities.^11,12 Syringocystadenoma papilliferum is a benign adnexal proliferation with apocrine differentiation that usually presents as a hairless papillomatous plaque or nodule measuring 1 to 4 cm in diameter and often is first noted at birth or during early childhood.⁷ Osteomyelitis is progressive inflammation of the periosteum and bone marrow that rapidly breaks through the periosteum and spreads to surrounding areas. The mandible is the most susceptible bone for facial osteomyelitis.⁸ Epidermoid cysts are formed by the proliferation of epidermal cells within a circumscribed dermal space. Infection of the cysts is characterized by redness, swelling, heat, and pain. As the infection progresses, suppurative inflammation develops, leading to local liquefaction and abscesses.⁹

This case was initially misdiagnosed as infectious skin lesions by outside clinicians. Multiple surgical treatments and long-term antibiotic therapy were attempted before the correct diagnosis was made. The clinical diagnosis of odontogenic cutaneous sinus tracts is challenging due to the variety of affected sites and clinical signs. Ultrasonography should be performed as early as possible to identify the disease and avoid unnecessary surgery. For appropriate dental therapy, close liaison with the stomatology department is warranted.

The Diagnosis: Cystic Neutrophilic Granulomatous Mastitis

The histopathologic findings in our patient were characteristic of cystic neutrophilic granulomatous mastitis (CNGM), a rare granulomatous mastitis associated with Corynebacterium and suppurative lipogranulomas. Although not seen in our patient, the lipid vacuoles may contain gram-positive bacilli.¹ The surrounding mixed inflammatory infiltrate contains Langerhans giant cells, lymphocytes, and neutrophils. Cystic neutrophilic granulomatous mastitis is seen in parous women of reproductive age. Physical examination demonstrates a palpable painful mass on the breast. Wound cultures frequently are negative, likely due to difficulty culturing Corynebacterium and prophylactic antibiotic treatment. Given the association with Corynebacterium species, early diagnosis of CNGM is essential in offering patients the most appropriate treatment. Prolonged antibiotic therapy specifically directed to corynebacteria is required, sometimes even beyond resolution of clinical symptoms. The diagnosis of CNGM often is missed or delayed due to its rarity and many potential mimickers. Clinically, CNGM may be virtually impossible to discern from invasive carcinoma.¹

Our patient was treated with vancomycin and cefepime with incision and drainage as an inpatient. Upon discharge, she was started on prednisone 1 mg/kg daily tapered by 10 mg every 5 days over 1 month and doxycycline 100 mg twice daily. She was then transitioned to topical hydrocortisone and bacitracin; she reported decreased swelling and pain. No new lesions formed after the initiation of therapy; however, most lesions remained open. Cystic neutrophilic granulomatous mastitis remains a challenging entity to treat, with a variable response rate reported in the literature for antibiotics such as doxycycline and systemic and topical steroids as well as immunosuppressants including methotrexate.^2,3

Cystic neutrophilic granulomatous mastitis can be distinguished from hidradenitis suppurativa clinically because ulcerating lesions can involve the superior portions of the breast in CNGM, whereas hidradenitis suppurativa typically is restricted to the lower intertriginous parts of the breast. Other mimics of CNGM can be distinguished with biopsy. Histology of pyoderma gangrenosum lacks prominent granuloma formation. Although sarcoidosis and mycobacterial infection show prominent granulomas, neither show the characteristic lipogranulomas seen in CNGM. Additionally, the granulomas of sarcoidosis are much larger and deeper than CNGM. Mycobacterial granulomas also typically reveal bacilli with acid-fast bacilli staining or via wound culture.

The Diagnosis: Cystic Neutrophilic Granulomatous Mastitis

The histopathologic findings in our patient were characteristic of cystic neutrophilic granulomatous mastitis (CNGM), a rare granulomatous mastitis associated with Corynebacterium and suppurative lipogranulomas. Although not seen in our patient, the lipid vacuoles may contain gram-positive bacilli.¹ The surrounding mixed inflammatory infiltrate contains Langerhans giant cells, lymphocytes, and neutrophils. Cystic neutrophilic granulomatous mastitis is seen in parous women of reproductive age. Physical examination demonstrates a palpable painful mass on the breast. Wound cultures frequently are negative, likely due to difficulty culturing Corynebacterium and prophylactic antibiotic treatment. Given the association with Corynebacterium species, early diagnosis of CNGM is essential in offering patients the most appropriate treatment. Prolonged antibiotic therapy specifically directed to corynebacteria is required, sometimes even beyond resolution of clinical symptoms. The diagnosis of CNGM often is missed or delayed due to its rarity and many potential mimickers. Clinically, CNGM may be virtually impossible to discern from invasive carcinoma.¹

Our patient was treated with vancomycin and cefepime with incision and drainage as an inpatient. Upon discharge, she was started on prednisone 1 mg/kg daily tapered by 10 mg every 5 days over 1 month and doxycycline 100 mg twice daily. She was then transitioned to topical hydrocortisone and bacitracin; she reported decreased swelling and pain. No new lesions formed after the initiation of therapy; however, most lesions remained open. Cystic neutrophilic granulomatous mastitis remains a challenging entity to treat, with a variable response rate reported in the literature for antibiotics such as doxycycline and systemic and topical steroids as well as immunosuppressants including methotrexate.^2,3

Cystic neutrophilic granulomatous mastitis can be distinguished from hidradenitis suppurativa clinically because ulcerating lesions can involve the superior portions of the breast in CNGM, whereas hidradenitis suppurativa typically is restricted to the lower intertriginous parts of the breast. Other mimics of CNGM can be distinguished with biopsy. Histology of pyoderma gangrenosum lacks prominent granuloma formation. Although sarcoidosis and mycobacterial infection show prominent granulomas, neither show the characteristic lipogranulomas seen in CNGM. Additionally, the granulomas of sarcoidosis are much larger and deeper than CNGM. Mycobacterial granulomas also typically reveal bacilli with acid-fast bacilli staining or via wound culture.

The Diagnosis: Cystic Neutrophilic Granulomatous Mastitis

The histopathologic findings in our patient were characteristic of cystic neutrophilic granulomatous mastitis (CNGM), a rare granulomatous mastitis associated with Corynebacterium and suppurative lipogranulomas. Although not seen in our patient, the lipid vacuoles may contain gram-positive bacilli.¹ The surrounding mixed inflammatory infiltrate contains Langerhans giant cells, lymphocytes, and neutrophils. Cystic neutrophilic granulomatous mastitis is seen in parous women of reproductive age. Physical examination demonstrates a palpable painful mass on the breast. Wound cultures frequently are negative, likely due to difficulty culturing Corynebacterium and prophylactic antibiotic treatment. Given the association with Corynebacterium species, early diagnosis of CNGM is essential in offering patients the most appropriate treatment. Prolonged antibiotic therapy specifically directed to corynebacteria is required, sometimes even beyond resolution of clinical symptoms. The diagnosis of CNGM often is missed or delayed due to its rarity and many potential mimickers. Clinically, CNGM may be virtually impossible to discern from invasive carcinoma.¹

Our patient was treated with vancomycin and cefepime with incision and drainage as an inpatient. Upon discharge, she was started on prednisone 1 mg/kg daily tapered by 10 mg every 5 days over 1 month and doxycycline 100 mg twice daily. She was then transitioned to topical hydrocortisone and bacitracin; she reported decreased swelling and pain. No new lesions formed after the initiation of therapy; however, most lesions remained open. Cystic neutrophilic granulomatous mastitis remains a challenging entity to treat, with a variable response rate reported in the literature for antibiotics such as doxycycline and systemic and topical steroids as well as immunosuppressants including methotrexate.^2,3

Cystic neutrophilic granulomatous mastitis can be distinguished from hidradenitis suppurativa clinically because ulcerating lesions can involve the superior portions of the breast in CNGM, whereas hidradenitis suppurativa typically is restricted to the lower intertriginous parts of the breast. Other mimics of CNGM can be distinguished with biopsy. Histology of pyoderma gangrenosum lacks prominent granuloma formation. Although sarcoidosis and mycobacterial infection show prominent granulomas, neither show the characteristic lipogranulomas seen in CNGM. Additionally, the granulomas of sarcoidosis are much larger and deeper than CNGM. Mycobacterial granulomas also typically reveal bacilli with acid-fast bacilli staining or via wound culture.

The Diagnosis: Bullous Pyoderma Gangrenosum

A bone marrow biopsy revealed 60% myeloblasts, leading to a diagnosis of acute myeloid leukemia (AML). A biopsy obtained from the edge of the bullous plaque demonstrated a dense dermal neutrophilic infiltrate with extravasated erythrocytes (Figure). Fite, Gram, and Grocott-Gomori methenamine-silver staining failed to reveal infectious organisms. Tissue and blood cultures were negative. Given the pathologic findings, clinical presentation including recent diagnosis of AML, and exclusion of other underlying disease processes including infection, the diagnosis of bullous pyoderma gangrenosum (PG) was made. The lesion improved with systemic steroids and treatment of the underlying AML with fludarabine and venetoclax chemotherapy.

First recognized in 1916 by French dermatologist Louis Brocq, MD, PG is a sterile neutrophilic dermatosis that predominantly affects women older than 50 years.^1,2 This disorder can develop idiopathically; secondary to trauma; or in association with systemic diseases such as inflammatory bowel disease, rheumatoid arthritis, and hematologic malignancies. The pathogenesis of PG remains unclear; however, overexpression of inflammatory cytokines may mediate its development by stimulating T cells and promoting neutrophilic chemotaxis.³

Pyoderma gangrenosum classically presents as a rapidly enlarging ulcer with cribriform scarring but manifests variably. Four variants of the disorder exist: classic ulcerative, pustular, bullous, and vegetative PG. Ulcerative PG is the most common variant. Bullous PG is associated with hematologic malignancies such as primary myelofibrosis, myelodysplastic disease, and AML. In these patients, hematologic malignancy often exists prior to the development of PG and portends a poorer prognosis. This association underscores the importance of timely diagnosis and thorough hematologic evaluation by obtaining a complete blood cell count with differential, peripheral smear, serum protein electrophoresis with immunofixation, and quantitative immunoglobulins (IgA, IgG, IgM). If any of the results are positive, prompt referral to a hematologist and bone marrow biopsy are paramount.³

The diagnosis of PG remains elusive, as no validated clinical or pathological criteria exist. Histopathologic evaluation may be nonspecific and variable depending on the subtype. Biopsy results for classic ulcerative PG may reveal a neutrophilic infiltrate with leukocytoclasia. Bullous PG may include subepidermal hemorrhagic bullae. Notably, bullous PG appears histologically similar to the superficial bullous variant of Sweet syndrome.

Sweet syndrome (also known as acute febrile neutrophilic dermatosis) is a type of neutrophilic dermatosis characterized by fever, neutrophilia, and the sudden onset of tender erythematous lesions. Variations include idiopathic, subcutaneous, and bullous Sweet syndrome, which present as plaques, nodules, or bullae, respectively.⁴ Similar to PG, Sweet syndrome can manifest in patients with hematologic malignancies. Both PG and Sweet syndrome are thought to exist along a continuum and can be considered intersecting diagnoses in the setting of leukemia or other hematologic malignancies.⁵ There have been reports of the coexistence of distinct PG and Sweet syndrome lesions on a single patient, further supporting the belief that these entities share a common pathologic mechanism.⁶ Sweet syndrome also commonly can be associated with upper respiratory infections; pregnancy; and medications, with culprits including granulocyte colony-stimulating factor, azathioprine, vemurafenib, and isotretinoin.⁷

Other differential diagnoses include brown recluse spider bite, bullous fixed drug eruption (FDE), and necrotizing fasciitis (NF). Venom from the brown recluse spider (Loxosceles reclusa) can trigger toxin-mediated hemolysis, complement-mediated erythrocyte destruction, and basement membrane zone degradation due to the synergistic effects of the toxin’s sphingomyelinase D and protease content.⁸ The inciting bite is painless. After 8 hours, the site becomes painful and pruritic and presents with peripheral erythema and central pallor. After 24 hours, the lesion blisters. The blister ruptures within 3 to 4 days, resulting in eschar formation with the subsequent development of an indurated blue ulcer with a stellate center. Ulcers can take months to heal.⁹ Based on the clinical findings in our patient, this diagnosis was less likely.

Fixed drug eruption is a localized cutaneous reaction that manifests in fixed locations minutes to days after exposure to medications such as trimethoprimsulfamethoxazole, nonsteroidal anti-inflammatory drugs, salicylates, and oral contraceptives. Commonly affected areas include the hands, legs, genitals, and trunk. Lesions initially present as well-demarcated, erythematous to violaceous, round plaques. A rarer variant manifesting as bullae also has been described. Careful consideration of the patient’s history and physical examination findings is sufficient for establishing this diagnosis; however, a punch biopsy can provide clarity. Histopathology reveals a lichenoid tissue reaction with dyskeratosis, broad epidermal necrosis, and damage to the stratum basalis. A lymphocytic perivascular infiltrate also may appear in the dermis.¹⁰ Both the clinical findings and histopathology of our case were not characteristic of FDE.

Necrotizing fasciitis is a fulminant, life-threatening, soft-tissue infection precipitated by polymicrobial flora. Early recognition of NF is difficult, as in its early stages it can mimic cellulitis. As the infection takes its course, necrosis can extend from the skin and into the subcutaneous tissue. Patients also develop fever, leukocytosis, and signs of sepsis. Histopathology demonstrates neutrophilic infiltration with bacterial invasion as well as necrosis of the superficial fascia and subepidermal edema.¹¹ Pyoderma gangrenosum previously has been reported to mimic NF; however, lack of responsiveness to antibiotic therapy would favor a diagnosis of PG over NF.¹²

Treatment of PG is driven by the extent of cutaneous involvement. In mild cases, wound care and topical therapy with corticosteroids and tacrolimus may suffice. Severe cases necessitate systemic therapy with oral corticosteroids or cyclosporine; biologic therapy also may play a role in treatment.⁴ In patients with hematologic malignancy, chemotherapy alone may partially or completely resolve the lesion; however, systemic corticosteroids commonly are included in management.³

The Diagnosis: Bullous Pyoderma Gangrenosum

A bone marrow biopsy revealed 60% myeloblasts, leading to a diagnosis of acute myeloid leukemia (AML). A biopsy obtained from the edge of the bullous plaque demonstrated a dense dermal neutrophilic infiltrate with extravasated erythrocytes (Figure). Fite, Gram, and Grocott-Gomori methenamine-silver staining failed to reveal infectious organisms. Tissue and blood cultures were negative. Given the pathologic findings, clinical presentation including recent diagnosis of AML, and exclusion of other underlying disease processes including infection, the diagnosis of bullous pyoderma gangrenosum (PG) was made. The lesion improved with systemic steroids and treatment of the underlying AML with fludarabine and venetoclax chemotherapy.

First recognized in 1916 by French dermatologist Louis Brocq, MD, PG is a sterile neutrophilic dermatosis that predominantly affects women older than 50 years.^1,2 This disorder can develop idiopathically; secondary to trauma; or in association with systemic diseases such as inflammatory bowel disease, rheumatoid arthritis, and hematologic malignancies. The pathogenesis of PG remains unclear; however, overexpression of inflammatory cytokines may mediate its development by stimulating T cells and promoting neutrophilic chemotaxis.³

Pyoderma gangrenosum classically presents as a rapidly enlarging ulcer with cribriform scarring but manifests variably. Four variants of the disorder exist: classic ulcerative, pustular, bullous, and vegetative PG. Ulcerative PG is the most common variant. Bullous PG is associated with hematologic malignancies such as primary myelofibrosis, myelodysplastic disease, and AML. In these patients, hematologic malignancy often exists prior to the development of PG and portends a poorer prognosis. This association underscores the importance of timely diagnosis and thorough hematologic evaluation by obtaining a complete blood cell count with differential, peripheral smear, serum protein electrophoresis with immunofixation, and quantitative immunoglobulins (IgA, IgG, IgM). If any of the results are positive, prompt referral to a hematologist and bone marrow biopsy are paramount.³

The diagnosis of PG remains elusive, as no validated clinical or pathological criteria exist. Histopathologic evaluation may be nonspecific and variable depending on the subtype. Biopsy results for classic ulcerative PG may reveal a neutrophilic infiltrate with leukocytoclasia. Bullous PG may include subepidermal hemorrhagic bullae. Notably, bullous PG appears histologically similar to the superficial bullous variant of Sweet syndrome.

Sweet syndrome (also known as acute febrile neutrophilic dermatosis) is a type of neutrophilic dermatosis characterized by fever, neutrophilia, and the sudden onset of tender erythematous lesions. Variations include idiopathic, subcutaneous, and bullous Sweet syndrome, which present as plaques, nodules, or bullae, respectively.⁴ Similar to PG, Sweet syndrome can manifest in patients with hematologic malignancies. Both PG and Sweet syndrome are thought to exist along a continuum and can be considered intersecting diagnoses in the setting of leukemia or other hematologic malignancies.⁵ There have been reports of the coexistence of distinct PG and Sweet syndrome lesions on a single patient, further supporting the belief that these entities share a common pathologic mechanism.⁶ Sweet syndrome also commonly can be associated with upper respiratory infections; pregnancy; and medications, with culprits including granulocyte colony-stimulating factor, azathioprine, vemurafenib, and isotretinoin.⁷

Other differential diagnoses include brown recluse spider bite, bullous fixed drug eruption (FDE), and necrotizing fasciitis (NF). Venom from the brown recluse spider (Loxosceles reclusa) can trigger toxin-mediated hemolysis, complement-mediated erythrocyte destruction, and basement membrane zone degradation due to the synergistic effects of the toxin’s sphingomyelinase D and protease content.⁸ The inciting bite is painless. After 8 hours, the site becomes painful and pruritic and presents with peripheral erythema and central pallor. After 24 hours, the lesion blisters. The blister ruptures within 3 to 4 days, resulting in eschar formation with the subsequent development of an indurated blue ulcer with a stellate center. Ulcers can take months to heal.⁹ Based on the clinical findings in our patient, this diagnosis was less likely.

Fixed drug eruption is a localized cutaneous reaction that manifests in fixed locations minutes to days after exposure to medications such as trimethoprimsulfamethoxazole, nonsteroidal anti-inflammatory drugs, salicylates, and oral contraceptives. Commonly affected areas include the hands, legs, genitals, and trunk. Lesions initially present as well-demarcated, erythematous to violaceous, round plaques. A rarer variant manifesting as bullae also has been described. Careful consideration of the patient’s history and physical examination findings is sufficient for establishing this diagnosis; however, a punch biopsy can provide clarity. Histopathology reveals a lichenoid tissue reaction with dyskeratosis, broad epidermal necrosis, and damage to the stratum basalis. A lymphocytic perivascular infiltrate also may appear in the dermis.¹⁰ Both the clinical findings and histopathology of our case were not characteristic of FDE.

Necrotizing fasciitis is a fulminant, life-threatening, soft-tissue infection precipitated by polymicrobial flora. Early recognition of NF is difficult, as in its early stages it can mimic cellulitis. As the infection takes its course, necrosis can extend from the skin and into the subcutaneous tissue. Patients also develop fever, leukocytosis, and signs of sepsis. Histopathology demonstrates neutrophilic infiltration with bacterial invasion as well as necrosis of the superficial fascia and subepidermal edema.¹¹ Pyoderma gangrenosum previously has been reported to mimic NF; however, lack of responsiveness to antibiotic therapy would favor a diagnosis of PG over NF.¹²

Treatment of PG is driven by the extent of cutaneous involvement. In mild cases, wound care and topical therapy with corticosteroids and tacrolimus may suffice. Severe cases necessitate systemic therapy with oral corticosteroids or cyclosporine; biologic therapy also may play a role in treatment.⁴ In patients with hematologic malignancy, chemotherapy alone may partially or completely resolve the lesion; however, systemic corticosteroids commonly are included in management.³

The Diagnosis: Bullous Pyoderma Gangrenosum

A bone marrow biopsy revealed 60% myeloblasts, leading to a diagnosis of acute myeloid leukemia (AML). A biopsy obtained from the edge of the bullous plaque demonstrated a dense dermal neutrophilic infiltrate with extravasated erythrocytes (Figure). Fite, Gram, and Grocott-Gomori methenamine-silver staining failed to reveal infectious organisms. Tissue and blood cultures were negative. Given the pathologic findings, clinical presentation including recent diagnosis of AML, and exclusion of other underlying disease processes including infection, the diagnosis of bullous pyoderma gangrenosum (PG) was made. The lesion improved with systemic steroids and treatment of the underlying AML with fludarabine and venetoclax chemotherapy.

First recognized in 1916 by French dermatologist Louis Brocq, MD, PG is a sterile neutrophilic dermatosis that predominantly affects women older than 50 years.^1,2 This disorder can develop idiopathically; secondary to trauma; or in association with systemic diseases such as inflammatory bowel disease, rheumatoid arthritis, and hematologic malignancies. The pathogenesis of PG remains unclear; however, overexpression of inflammatory cytokines may mediate its development by stimulating T cells and promoting neutrophilic chemotaxis.³

Pyoderma gangrenosum classically presents as a rapidly enlarging ulcer with cribriform scarring but manifests variably. Four variants of the disorder exist: classic ulcerative, pustular, bullous, and vegetative PG. Ulcerative PG is the most common variant. Bullous PG is associated with hematologic malignancies such as primary myelofibrosis, myelodysplastic disease, and AML. In these patients, hematologic malignancy often exists prior to the development of PG and portends a poorer prognosis. This association underscores the importance of timely diagnosis and thorough hematologic evaluation by obtaining a complete blood cell count with differential, peripheral smear, serum protein electrophoresis with immunofixation, and quantitative immunoglobulins (IgA, IgG, IgM). If any of the results are positive, prompt referral to a hematologist and bone marrow biopsy are paramount.³

The diagnosis of PG remains elusive, as no validated clinical or pathological criteria exist. Histopathologic evaluation may be nonspecific and variable depending on the subtype. Biopsy results for classic ulcerative PG may reveal a neutrophilic infiltrate with leukocytoclasia. Bullous PG may include subepidermal hemorrhagic bullae. Notably, bullous PG appears histologically similar to the superficial bullous variant of Sweet syndrome.

Sweet syndrome (also known as acute febrile neutrophilic dermatosis) is a type of neutrophilic dermatosis characterized by fever, neutrophilia, and the sudden onset of tender erythematous lesions. Variations include idiopathic, subcutaneous, and bullous Sweet syndrome, which present as plaques, nodules, or bullae, respectively.⁴ Similar to PG, Sweet syndrome can manifest in patients with hematologic malignancies. Both PG and Sweet syndrome are thought to exist along a continuum and can be considered intersecting diagnoses in the setting of leukemia or other hematologic malignancies.⁵ There have been reports of the coexistence of distinct PG and Sweet syndrome lesions on a single patient, further supporting the belief that these entities share a common pathologic mechanism.⁶ Sweet syndrome also commonly can be associated with upper respiratory infections; pregnancy; and medications, with culprits including granulocyte colony-stimulating factor, azathioprine, vemurafenib, and isotretinoin.⁷

Other differential diagnoses include brown recluse spider bite, bullous fixed drug eruption (FDE), and necrotizing fasciitis (NF). Venom from the brown recluse spider (Loxosceles reclusa) can trigger toxin-mediated hemolysis, complement-mediated erythrocyte destruction, and basement membrane zone degradation due to the synergistic effects of the toxin’s sphingomyelinase D and protease content.⁸ The inciting bite is painless. After 8 hours, the site becomes painful and pruritic and presents with peripheral erythema and central pallor. After 24 hours, the lesion blisters. The blister ruptures within 3 to 4 days, resulting in eschar formation with the subsequent development of an indurated blue ulcer with a stellate center. Ulcers can take months to heal.⁹ Based on the clinical findings in our patient, this diagnosis was less likely.

Fixed drug eruption is a localized cutaneous reaction that manifests in fixed locations minutes to days after exposure to medications such as trimethoprimsulfamethoxazole, nonsteroidal anti-inflammatory drugs, salicylates, and oral contraceptives. Commonly affected areas include the hands, legs, genitals, and trunk. Lesions initially present as well-demarcated, erythematous to violaceous, round plaques. A rarer variant manifesting as bullae also has been described. Careful consideration of the patient’s history and physical examination findings is sufficient for establishing this diagnosis; however, a punch biopsy can provide clarity. Histopathology reveals a lichenoid tissue reaction with dyskeratosis, broad epidermal necrosis, and damage to the stratum basalis. A lymphocytic perivascular infiltrate also may appear in the dermis.¹⁰ Both the clinical findings and histopathology of our case were not characteristic of FDE.

Necrotizing fasciitis is a fulminant, life-threatening, soft-tissue infection precipitated by polymicrobial flora. Early recognition of NF is difficult, as in its early stages it can mimic cellulitis. As the infection takes its course, necrosis can extend from the skin and into the subcutaneous tissue. Patients also develop fever, leukocytosis, and signs of sepsis. Histopathology demonstrates neutrophilic infiltration with bacterial invasion as well as necrosis of the superficial fascia and subepidermal edema.¹¹ Pyoderma gangrenosum previously has been reported to mimic NF; however, lack of responsiveness to antibiotic therapy would favor a diagnosis of PG over NF.¹²

Treatment of PG is driven by the extent of cutaneous involvement. In mild cases, wound care and topical therapy with corticosteroids and tacrolimus may suffice. Severe cases necessitate systemic therapy with oral corticosteroids or cyclosporine; biologic therapy also may play a role in treatment.⁴ In patients with hematologic malignancy, chemotherapy alone may partially or completely resolve the lesion; however, systemic corticosteroids commonly are included in management.³

The Diagnosis: Leishmaniasis

Hematoxylin and eosin staining of the tissue specimen revealed a dense histiocytic infiltrate with scattered lymphocytes and neutrophils. There were round to oval basophilic structures within the macrophages consistent with amastigotes. Giemsa staining was not necessary to visualize the organisms. The infiltrate abutted the overlying epidermis, which was acanthotic with pseudoepitheliomatous hyperplasia. There were collections of neutrophils, parakeratosis, and a serum crust overlying the epidermis (Figure). Clinical and histologic findings, as well as travel history, led to a diagnosis of cutaneous leishmaniasis (CL).

Leishmaniases is a group of diseases caused by a parasitic infection with flagellated protozoa of the genus Leishmania. There are more than 20 different Leishmania species that are pathogenic to humans, all presenting with cutaneous findings. The presentation depends on the inoculating species and the host cellular immune response and includes cutaneous, mucosal, and visceral involvement. The disease is transmitted via the bite of an infected bloodsucking female sand fly.¹ There are approximately 30 different species of sand flies that are proven to be vectors of the disease, with up to 40 more suspected of involvement in transmission, predominantly from the genera Phlebotomus (Old World) and Lutzomyia (New World).^1,2 There are an estimated 1 to 2 million new cases of cutaneous leishmaniasis diagnosed annually in 70 endemic countries of the tropics, subtropics, and southern Europe.^1,3,4

The differential diagnosis included cutaneous tuberculosis, which can have a similar progression and clinical appearance. Cutaneous tuberculosis starts as firm, reddish-brown, painless papules that slowly enlarge and ulcerate.⁵ It may be further differentiated on histopathology by the presence of tuberculoid granulomas, caseating necrosis, and acid-fast bacilli, which are easily detected in early lesions but are less prevalent after the granuloma develops.⁶ Sporotrichosis presents as a nodule, which may or may not ulcerate, on the extremities. However, the classic morphology is a sporotrichoid pattern, which describes the initial lesion plus subcutaneous nodular spread along the lymphatics.⁷ On histology, sporotrichosis has a characteristic “sporotrichoid asteroid” comprised of the yeast form surrounded by eosinophilic hyaline material in raylike processes that are found in the center of suppurative granulomas or foci.⁸

Atypical mycobacteria, principally Mycobacterium marinum (swimming pool granuloma) and Mycobacterium ulcerans (Buruli ulcer), are capable of causing cutaneous infections. They may be differentiated histologically by a neutrophilic infiltrate of poorly formed granulomas without caseation and extensive coagulative necrosis with little cellular infiltrate, respectively.⁶ Histoplasma capsulatum also infects histiocytes and may appear similar in size and shape; however, histoplasmosis is surrounded by a pseudocapsule and evenly spaced.⁸

Conversely, the histology of leishmaniasis lacks a pseudocapsule. The amastigotes may form the classic marquee sign by lining the periphery of the macrophage or they can be randomly spaced. Classically, the epidermis shows hyperkeratosis and acanthosis. Sometimes atrophy, ulceration, or intraepidermal abscesses also can be observed. Pseudoepitheliomatous hyperplasia can be seen in some long-standing lesions.^1,4 Many of these findings were observed on hematoxylin and eosin staining from a punch biopsy obtained from the center of the lesion in our patient. For further delineation, a speciation kit was obtained from Walter Reed National Military Medical Center (Bethesda, Maryland). A second punch biopsy was obtained from the lesion edge, sectioned into 4 individual pieces, and placed in Schneider tissue culture medium. It was sent for tissue culture, polymerase chain reaction, and histology. Polymerase chain reaction analysis was positive for Leishmania, which was further identified as Leishmania tropica by tissue culture.

Leishmania tropica (Old World CL) commonly causes CL and is endemic to Central Asia, the Middle East, parts of North Africa, and Southeast Asia. Old and New World CL start as a small erythematous papule after a bite from an infected female sand fly. The papule develops into a nodule over weeks to months. The lesion may ulcerate and typically heals leaving an atrophic scar in months to years.¹ Speciation of CL is important to guide therapy.

Leishmania mexicana, a New World species that commonly causes CL, classically is found in Central and South America, but there also have been documented cases in Texas. A 2008 case series identified 9 cases in northern Texas in residents without a travel history to endemic locations.⁹ Similarly, a cross-sectional study identified 41 locally endemic cases of CL over a 10-year period (2007-2017) in Texas; 22 of these cases had speciation by polymerase chain reaction, and all cases were attributed to L mexicana.¹⁰

In the United States, CL classically has been associated with travelers and military personnel returning from the Middle East; however, a growing body of literature suggests that it may be endemic to Texas, where it is now a reportable disease. Physicians should have an increased awareness of this entity and a high index of suspicion when treating patients with nonhealing cutaneous lesions.

The Diagnosis: Leishmaniasis

Hematoxylin and eosin staining of the tissue specimen revealed a dense histiocytic infiltrate with scattered lymphocytes and neutrophils. There were round to oval basophilic structures within the macrophages consistent with amastigotes. Giemsa staining was not necessary to visualize the organisms. The infiltrate abutted the overlying epidermis, which was acanthotic with pseudoepitheliomatous hyperplasia. There were collections of neutrophils, parakeratosis, and a serum crust overlying the epidermis (Figure). Clinical and histologic findings, as well as travel history, led to a diagnosis of cutaneous leishmaniasis (CL).

Leishmaniases is a group of diseases caused by a parasitic infection with flagellated protozoa of the genus Leishmania. There are more than 20 different Leishmania species that are pathogenic to humans, all presenting with cutaneous findings. The presentation depends on the inoculating species and the host cellular immune response and includes cutaneous, mucosal, and visceral involvement. The disease is transmitted via the bite of an infected bloodsucking female sand fly.¹ There are approximately 30 different species of sand flies that are proven to be vectors of the disease, with up to 40 more suspected of involvement in transmission, predominantly from the genera Phlebotomus (Old World) and Lutzomyia (New World).^1,2 There are an estimated 1 to 2 million new cases of cutaneous leishmaniasis diagnosed annually in 70 endemic countries of the tropics, subtropics, and southern Europe.^1,3,4

The differential diagnosis included cutaneous tuberculosis, which can have a similar progression and clinical appearance. Cutaneous tuberculosis starts as firm, reddish-brown, painless papules that slowly enlarge and ulcerate.⁵ It may be further differentiated on histopathology by the presence of tuberculoid granulomas, caseating necrosis, and acid-fast bacilli, which are easily detected in early lesions but are less prevalent after the granuloma develops.⁶ Sporotrichosis presents as a nodule, which may or may not ulcerate, on the extremities. However, the classic morphology is a sporotrichoid pattern, which describes the initial lesion plus subcutaneous nodular spread along the lymphatics.⁷ On histology, sporotrichosis has a characteristic “sporotrichoid asteroid” comprised of the yeast form surrounded by eosinophilic hyaline material in raylike processes that are found in the center of suppurative granulomas or foci.⁸

Atypical mycobacteria, principally Mycobacterium marinum (swimming pool granuloma) and Mycobacterium ulcerans (Buruli ulcer), are capable of causing cutaneous infections. They may be differentiated histologically by a neutrophilic infiltrate of poorly formed granulomas without caseation and extensive coagulative necrosis with little cellular infiltrate, respectively.⁶ Histoplasma capsulatum also infects histiocytes and may appear similar in size and shape; however, histoplasmosis is surrounded by a pseudocapsule and evenly spaced.⁸

Conversely, the histology of leishmaniasis lacks a pseudocapsule. The amastigotes may form the classic marquee sign by lining the periphery of the macrophage or they can be randomly spaced. Classically, the epidermis shows hyperkeratosis and acanthosis. Sometimes atrophy, ulceration, or intraepidermal abscesses also can be observed. Pseudoepitheliomatous hyperplasia can be seen in some long-standing lesions.^1,4 Many of these findings were observed on hematoxylin and eosin staining from a punch biopsy obtained from the center of the lesion in our patient. For further delineation, a speciation kit was obtained from Walter Reed National Military Medical Center (Bethesda, Maryland). A second punch biopsy was obtained from the lesion edge, sectioned into 4 individual pieces, and placed in Schneider tissue culture medium. It was sent for tissue culture, polymerase chain reaction, and histology. Polymerase chain reaction analysis was positive for Leishmania, which was further identified as Leishmania tropica by tissue culture.

Leishmania tropica (Old World CL) commonly causes CL and is endemic to Central Asia, the Middle East, parts of North Africa, and Southeast Asia. Old and New World CL start as a small erythematous papule after a bite from an infected female sand fly. The papule develops into a nodule over weeks to months. The lesion may ulcerate and typically heals leaving an atrophic scar in months to years.¹ Speciation of CL is important to guide therapy.

Leishmania mexicana, a New World species that commonly causes CL, classically is found in Central and South America, but there also have been documented cases in Texas. A 2008 case series identified 9 cases in northern Texas in residents without a travel history to endemic locations.⁹ Similarly, a cross-sectional study identified 41 locally endemic cases of CL over a 10-year period (2007-2017) in Texas; 22 of these cases had speciation by polymerase chain reaction, and all cases were attributed to L mexicana.¹⁰

In the United States, CL classically has been associated with travelers and military personnel returning from the Middle East; however, a growing body of literature suggests that it may be endemic to Texas, where it is now a reportable disease. Physicians should have an increased awareness of this entity and a high index of suspicion when treating patients with nonhealing cutaneous lesions.

The Diagnosis: Leishmaniasis

Hematoxylin and eosin staining of the tissue specimen revealed a dense histiocytic infiltrate with scattered lymphocytes and neutrophils. There were round to oval basophilic structures within the macrophages consistent with amastigotes. Giemsa staining was not necessary to visualize the organisms. The infiltrate abutted the overlying epidermis, which was acanthotic with pseudoepitheliomatous hyperplasia. There were collections of neutrophils, parakeratosis, and a serum crust overlying the epidermis (Figure). Clinical and histologic findings, as well as travel history, led to a diagnosis of cutaneous leishmaniasis (CL).

Leishmaniases is a group of diseases caused by a parasitic infection with flagellated protozoa of the genus Leishmania. There are more than 20 different Leishmania species that are pathogenic to humans, all presenting with cutaneous findings. The presentation depends on the inoculating species and the host cellular immune response and includes cutaneous, mucosal, and visceral involvement. The disease is transmitted via the bite of an infected bloodsucking female sand fly.¹ There are approximately 30 different species of sand flies that are proven to be vectors of the disease, with up to 40 more suspected of involvement in transmission, predominantly from the genera Phlebotomus (Old World) and Lutzomyia (New World).^1,2 There are an estimated 1 to 2 million new cases of cutaneous leishmaniasis diagnosed annually in 70 endemic countries of the tropics, subtropics, and southern Europe.^1,3,4

The differential diagnosis included cutaneous tuberculosis, which can have a similar progression and clinical appearance. Cutaneous tuberculosis starts as firm, reddish-brown, painless papules that slowly enlarge and ulcerate.⁵ It may be further differentiated on histopathology by the presence of tuberculoid granulomas, caseating necrosis, and acid-fast bacilli, which are easily detected in early lesions but are less prevalent after the granuloma develops.⁶ Sporotrichosis presents as a nodule, which may or may not ulcerate, on the extremities. However, the classic morphology is a sporotrichoid pattern, which describes the initial lesion plus subcutaneous nodular spread along the lymphatics.⁷ On histology, sporotrichosis has a characteristic “sporotrichoid asteroid” comprised of the yeast form surrounded by eosinophilic hyaline material in raylike processes that are found in the center of suppurative granulomas or foci.⁸

Atypical mycobacteria, principally Mycobacterium marinum (swimming pool granuloma) and Mycobacterium ulcerans (Buruli ulcer), are capable of causing cutaneous infections. They may be differentiated histologically by a neutrophilic infiltrate of poorly formed granulomas without caseation and extensive coagulative necrosis with little cellular infiltrate, respectively.⁶ Histoplasma capsulatum also infects histiocytes and may appear similar in size and shape; however, histoplasmosis is surrounded by a pseudocapsule and evenly spaced.⁸

Conversely, the histology of leishmaniasis lacks a pseudocapsule. The amastigotes may form the classic marquee sign by lining the periphery of the macrophage or they can be randomly spaced. Classically, the epidermis shows hyperkeratosis and acanthosis. Sometimes atrophy, ulceration, or intraepidermal abscesses also can be observed. Pseudoepitheliomatous hyperplasia can be seen in some long-standing lesions.^1,4 Many of these findings were observed on hematoxylin and eosin staining from a punch biopsy obtained from the center of the lesion in our patient. For further delineation, a speciation kit was obtained from Walter Reed National Military Medical Center (Bethesda, Maryland). A second punch biopsy was obtained from the lesion edge, sectioned into 4 individual pieces, and placed in Schneider tissue culture medium. It was sent for tissue culture, polymerase chain reaction, and histology. Polymerase chain reaction analysis was positive for Leishmania, which was further identified as Leishmania tropica by tissue culture.

Leishmania tropica (Old World CL) commonly causes CL and is endemic to Central Asia, the Middle East, parts of North Africa, and Southeast Asia. Old and New World CL start as a small erythematous papule after a bite from an infected female sand fly. The papule develops into a nodule over weeks to months. The lesion may ulcerate and typically heals leaving an atrophic scar in months to years.¹ Speciation of CL is important to guide therapy.

Leishmania mexicana, a New World species that commonly causes CL, classically is found in Central and South America, but there also have been documented cases in Texas. A 2008 case series identified 9 cases in northern Texas in residents without a travel history to endemic locations.⁹ Similarly, a cross-sectional study identified 41 locally endemic cases of CL over a 10-year period (2007-2017) in Texas; 22 of these cases had speciation by polymerase chain reaction, and all cases were attributed to L mexicana.¹⁰

In the United States, CL classically has been associated with travelers and military personnel returning from the Middle East; however, a growing body of literature suggests that it may be endemic to Texas, where it is now a reportable disease. Physicians should have an increased awareness of this entity and a high index of suspicion when treating patients with nonhealing cutaneous lesions.

The Diagnosis: Basal Cell Carcinoma

Histopathology was consistent with fungating basal cell carcinoma (BCC). The nodules were comprised of syncytial basaloid cells with high nuclear to cytoplasmic ratios, numerous mitotic figures, fibromyxoid stroma, and peripheral nuclear palisading (Figure). Fortunately, no perineural or lymphovascular invasion was identified, and the margins of the specimen were negative. Despite the high-risk nature of giant BCC, the mass was solitary without notable local invasion, leaving it amendable to surgery. On follow-up, the patient has remained recurrence free, and her hemoglobin level has since stabilized.

Skin cancer is the most common malignancy worldwide, and BCC accounts for more than 80% of nonmelanoma skin cancers in the United States. The incidence is on the rise due to the aging population and increasing cumulative skin exposure.¹ Risk factors include both individual physical characteristics and environmental exposures. Individuals with lighter skin tones, red and blonde hair, and blue and green eyes are at an increased risk.² UV radiation exposure is the most important cause of BCC.³ Chronic immunosuppression and exposure to arsenic, ionizing radiation, and psoralen plus UVA radiation also have been linked to the development of BCC.^4-6 Basal cell carcinomas most commonly arise on sun-exposed areas such as the face, though more than 10% of cases appear on the trunk.⁷ Lesions characteristically remain localized, and growth rate is variable; however, when left untreated, BCCs have the potential to become locally destructive and difficult to treat.

Advanced BCCs are tumors that penetrate deeply into the skin. They often are not amenable to traditional therapy and/ or metastasize. Those that grow to a diameter greater than 5 cm, as in our patient, are known as giant BCCs. Only 0.5% to 1% of BCCs are giant BCCs⁸ ; they typically are more aggressive in nature with higher rates of local recurrence and metastasis. Individuals who develop giant BCCs either have had a delay in access to medical care or a history of BCC that was inadequately managed.^9,10 During the COVID-19 pandemic, patient access to health care was substantially impacted during lockdowns. As in our patient, skin neoplasms and other medical conditions may present in later stages due to medical neglect.^11,12 Metastasis is rare, even in advanced BCCs. A review of the literature from 1984 estimated that the incidence of metastasis of BCCs is 1 in 1000 to 35,000. Metastasis portends a poor prognosis with a median overall survival of 8 to 14 months.¹³ An updated review in 2013 found similar outcomes.¹⁴

The choice of management for BCCs depends on the risk for recurrence as well as individual patient factors. Characteristics such as tumor size, location, histology, whether it is a primary or recurrent lesion, and the presence of chronic skin disease determine the recurrence rate.¹⁵ The management of advanced BCCs often requires a multidisciplinary approach, as these neoplasms may not be amenable to local therapy without causing substantial morbidity. Mohs micrographic surgery is the treatment of choice for BCCs at high risk for recurrence.¹⁶ Standard surgical excision with postoperative margin assessment is acceptable when Mohs micrographic surgery is not available.¹⁷ Radiation therapy is an alternative for patients who are not candidates for surgery.¹⁸

Recently, improved understanding of the molecular pathogenesis of BCCs has led to the development of novel systemic therapies. The Hedgehog signaling pathway has been found to play a critical role in the development of most BCCs.¹⁹ Vismodegib and sonidegib are small-molecule inhibitors of the Hedgehog signaling pathway approved for the treatment of locally advanced and metastatic BCCs that are not amenable to surgery or radiation. Approximately 50% of advanced BCCs respond to these therapies; however, long-term treatment may be limited by intolerable side effects and the development of resistance.²⁰ Basal cell carcinomas that spread to lymph nodes or distant sites are treated with traditional systemic therapy. Historically, conventional cytotoxic chemotherapies, such as platinum-containing regimens, were employed with limited benefit and notable morbidity.²¹

The differential diagnosis for our patient included several other cutaneous neoplasms. Squamous cell carcinoma is the second most common type of skin cancer. Similar to BCC, it can reach a substantial size if left untreated. Risk factors include chronic inflammation, exposure to radiation or chemical carcinogens, burns, human papillomavirus, and other chronic infections. Giant squamous cell carcinomas have high malignant potential and require imaging to assess the extent of invasion and for metastasis. Surgery typically is necessary for both staging and treatment. Adjuvant therapy also may be necessary.^22,23

Internal malignant neoplasms rarely present as cutaneous metastases. Breast cancer, melanoma, and cancers of the upper respiratory tract most frequently metastasize to the skin. Although colorectal cancer (CRC) rarely metastasizes to the skin, it is an important cause of cutaneous metastasis due to its high incidence in the general population. When it does spread to the skin, CRC preferentially affects the abdominal wall. Lesions typically resemble the primary tumor but may appear anaplastic. The occurrence of cutaneous metastasis suggests latestage disease and carries a poor prognosis.²⁴

Merkel cell carcinoma and melanoma are aggressive skin cancers with high mortality rates. The former is rarer but more lethal. Merkel cell carcinomas typically occur in elderly white men on sun-exposed areas of the skin. Tumors present as asymptomatic, rapidly expanding, blue-red, firm nodules. Immunosuppression and UV light exposure are notable risk factors.²⁵ Of the 4 major subtypes of cutaneous melanoma, superficial spreading is the most common, followed by nodular, lentigo maligna, and acral lentiginous.²⁶ Superficial spreading melanoma characteristically presents as an expanding asymmetric macule or thin plaque with irregular borders and variation in size and color (black, brown, or red). Nodular melanoma usually presents as symmetric in shape and color (amelanotic, black, or brown). Early recognition by both the patient and clinician is essential in preventing tumor growth and progression.²⁷

Our patient’s presentation was highly concerning for cutaneous metastasis given her history of CRC. Furthermore, the finding of severe anemia was atypical for skin cancer and more characteristic of the prior malignancy. Imaging revealed a locally confined mass with no evidence of extension, lymph node involvement, or additional lesions. The diagnosis was clinched with histopathologic examination.

The Diagnosis: Basal Cell Carcinoma

Histopathology was consistent with fungating basal cell carcinoma (BCC). The nodules were comprised of syncytial basaloid cells with high nuclear to cytoplasmic ratios, numerous mitotic figures, fibromyxoid stroma, and peripheral nuclear palisading (Figure). Fortunately, no perineural or lymphovascular invasion was identified, and the margins of the specimen were negative. Despite the high-risk nature of giant BCC, the mass was solitary without notable local invasion, leaving it amendable to surgery. On follow-up, the patient has remained recurrence free, and her hemoglobin level has since stabilized.

Skin cancer is the most common malignancy worldwide, and BCC accounts for more than 80% of nonmelanoma skin cancers in the United States. The incidence is on the rise due to the aging population and increasing cumulative skin exposure.¹ Risk factors include both individual physical characteristics and environmental exposures. Individuals with lighter skin tones, red and blonde hair, and blue and green eyes are at an increased risk.² UV radiation exposure is the most important cause of BCC.³ Chronic immunosuppression and exposure to arsenic, ionizing radiation, and psoralen plus UVA radiation also have been linked to the development of BCC.^4-6 Basal cell carcinomas most commonly arise on sun-exposed areas such as the face, though more than 10% of cases appear on the trunk.⁷ Lesions characteristically remain localized, and growth rate is variable; however, when left untreated, BCCs have the potential to become locally destructive and difficult to treat.

Advanced BCCs are tumors that penetrate deeply into the skin. They often are not amenable to traditional therapy and/ or metastasize. Those that grow to a diameter greater than 5 cm, as in our patient, are known as giant BCCs. Only 0.5% to 1% of BCCs are giant BCCs⁸ ; they typically are more aggressive in nature with higher rates of local recurrence and metastasis. Individuals who develop giant BCCs either have had a delay in access to medical care or a history of BCC that was inadequately managed.^9,10 During the COVID-19 pandemic, patient access to health care was substantially impacted during lockdowns. As in our patient, skin neoplasms and other medical conditions may present in later stages due to medical neglect.^11,12 Metastasis is rare, even in advanced BCCs. A review of the literature from 1984 estimated that the incidence of metastasis of BCCs is 1 in 1000 to 35,000. Metastasis portends a poor prognosis with a median overall survival of 8 to 14 months.¹³ An updated review in 2013 found similar outcomes.¹⁴

The choice of management for BCCs depends on the risk for recurrence as well as individual patient factors. Characteristics such as tumor size, location, histology, whether it is a primary or recurrent lesion, and the presence of chronic skin disease determine the recurrence rate.¹⁵ The management of advanced BCCs often requires a multidisciplinary approach, as these neoplasms may not be amenable to local therapy without causing substantial morbidity. Mohs micrographic surgery is the treatment of choice for BCCs at high risk for recurrence.¹⁶ Standard surgical excision with postoperative margin assessment is acceptable when Mohs micrographic surgery is not available.¹⁷ Radiation therapy is an alternative for patients who are not candidates for surgery.¹⁸

Recently, improved understanding of the molecular pathogenesis of BCCs has led to the development of novel systemic therapies. The Hedgehog signaling pathway has been found to play a critical role in the development of most BCCs.¹⁹ Vismodegib and sonidegib are small-molecule inhibitors of the Hedgehog signaling pathway approved for the treatment of locally advanced and metastatic BCCs that are not amenable to surgery or radiation. Approximately 50% of advanced BCCs respond to these therapies; however, long-term treatment may be limited by intolerable side effects and the development of resistance.²⁰ Basal cell carcinomas that spread to lymph nodes or distant sites are treated with traditional systemic therapy. Historically, conventional cytotoxic chemotherapies, such as platinum-containing regimens, were employed with limited benefit and notable morbidity.²¹

The differential diagnosis for our patient included several other cutaneous neoplasms. Squamous cell carcinoma is the second most common type of skin cancer. Similar to BCC, it can reach a substantial size if left untreated. Risk factors include chronic inflammation, exposure to radiation or chemical carcinogens, burns, human papillomavirus, and other chronic infections. Giant squamous cell carcinomas have high malignant potential and require imaging to assess the extent of invasion and for metastasis. Surgery typically is necessary for both staging and treatment. Adjuvant therapy also may be necessary.^22,23

Internal malignant neoplasms rarely present as cutaneous metastases. Breast cancer, melanoma, and cancers of the upper respiratory tract most frequently metastasize to the skin. Although colorectal cancer (CRC) rarely metastasizes to the skin, it is an important cause of cutaneous metastasis due to its high incidence in the general population. When it does spread to the skin, CRC preferentially affects the abdominal wall. Lesions typically resemble the primary tumor but may appear anaplastic. The occurrence of cutaneous metastasis suggests latestage disease and carries a poor prognosis.²⁴

Merkel cell carcinoma and melanoma are aggressive skin cancers with high mortality rates. The former is rarer but more lethal. Merkel cell carcinomas typically occur in elderly white men on sun-exposed areas of the skin. Tumors present as asymptomatic, rapidly expanding, blue-red, firm nodules. Immunosuppression and UV light exposure are notable risk factors.²⁵ Of the 4 major subtypes of cutaneous melanoma, superficial spreading is the most common, followed by nodular, lentigo maligna, and acral lentiginous.²⁶ Superficial spreading melanoma characteristically presents as an expanding asymmetric macule or thin plaque with irregular borders and variation in size and color (black, brown, or red). Nodular melanoma usually presents as symmetric in shape and color (amelanotic, black, or brown). Early recognition by both the patient and clinician is essential in preventing tumor growth and progression.²⁷

Our patient’s presentation was highly concerning for cutaneous metastasis given her history of CRC. Furthermore, the finding of severe anemia was atypical for skin cancer and more characteristic of the prior malignancy. Imaging revealed a locally confined mass with no evidence of extension, lymph node involvement, or additional lesions. The diagnosis was clinched with histopathologic examination.

The Diagnosis: Basal Cell Carcinoma

Histopathology was consistent with fungating basal cell carcinoma (BCC). The nodules were comprised of syncytial basaloid cells with high nuclear to cytoplasmic ratios, numerous mitotic figures, fibromyxoid stroma, and peripheral nuclear palisading (Figure). Fortunately, no perineural or lymphovascular invasion was identified, and the margins of the specimen were negative. Despite the high-risk nature of giant BCC, the mass was solitary without notable local invasion, leaving it amendable to surgery. On follow-up, the patient has remained recurrence free, and her hemoglobin level has since stabilized.

Skin cancer is the most common malignancy worldwide, and BCC accounts for more than 80% of nonmelanoma skin cancers in the United States. The incidence is on the rise due to the aging population and increasing cumulative skin exposure.¹ Risk factors include both individual physical characteristics and environmental exposures. Individuals with lighter skin tones, red and blonde hair, and blue and green eyes are at an increased risk.² UV radiation exposure is the most important cause of BCC.³ Chronic immunosuppression and exposure to arsenic, ionizing radiation, and psoralen plus UVA radiation also have been linked to the development of BCC.^4-6 Basal cell carcinomas most commonly arise on sun-exposed areas such as the face, though more than 10% of cases appear on the trunk.⁷ Lesions characteristically remain localized, and growth rate is variable; however, when left untreated, BCCs have the potential to become locally destructive and difficult to treat.

Advanced BCCs are tumors that penetrate deeply into the skin. They often are not amenable to traditional therapy and/ or metastasize. Those that grow to a diameter greater than 5 cm, as in our patient, are known as giant BCCs. Only 0.5% to 1% of BCCs are giant BCCs⁸ ; they typically are more aggressive in nature with higher rates of local recurrence and metastasis. Individuals who develop giant BCCs either have had a delay in access to medical care or a history of BCC that was inadequately managed.^9,10 During the COVID-19 pandemic, patient access to health care was substantially impacted during lockdowns. As in our patient, skin neoplasms and other medical conditions may present in later stages due to medical neglect.^11,12 Metastasis is rare, even in advanced BCCs. A review of the literature from 1984 estimated that the incidence of metastasis of BCCs is 1 in 1000 to 35,000. Metastasis portends a poor prognosis with a median overall survival of 8 to 14 months.¹³ An updated review in 2013 found similar outcomes.¹⁴

The choice of management for BCCs depends on the risk for recurrence as well as individual patient factors. Characteristics such as tumor size, location, histology, whether it is a primary or recurrent lesion, and the presence of chronic skin disease determine the recurrence rate.¹⁵ The management of advanced BCCs often requires a multidisciplinary approach, as these neoplasms may not be amenable to local therapy without causing substantial morbidity. Mohs micrographic surgery is the treatment of choice for BCCs at high risk for recurrence.¹⁶ Standard surgical excision with postoperative margin assessment is acceptable when Mohs micrographic surgery is not available.¹⁷ Radiation therapy is an alternative for patients who are not candidates for surgery.¹⁸

Recently, improved understanding of the molecular pathogenesis of BCCs has led to the development of novel systemic therapies. The Hedgehog signaling pathway has been found to play a critical role in the development of most BCCs.¹⁹ Vismodegib and sonidegib are small-molecule inhibitors of the Hedgehog signaling pathway approved for the treatment of locally advanced and metastatic BCCs that are not amenable to surgery or radiation. Approximately 50% of advanced BCCs respond to these therapies; however, long-term treatment may be limited by intolerable side effects and the development of resistance.²⁰ Basal cell carcinomas that spread to lymph nodes or distant sites are treated with traditional systemic therapy. Historically, conventional cytotoxic chemotherapies, such as platinum-containing regimens, were employed with limited benefit and notable morbidity.²¹

The differential diagnosis for our patient included several other cutaneous neoplasms. Squamous cell carcinoma is the second most common type of skin cancer. Similar to BCC, it can reach a substantial size if left untreated. Risk factors include chronic inflammation, exposure to radiation or chemical carcinogens, burns, human papillomavirus, and other chronic infections. Giant squamous cell carcinomas have high malignant potential and require imaging to assess the extent of invasion and for metastasis. Surgery typically is necessary for both staging and treatment. Adjuvant therapy also may be necessary.^22,23

Internal malignant neoplasms rarely present as cutaneous metastases. Breast cancer, melanoma, and cancers of the upper respiratory tract most frequently metastasize to the skin. Although colorectal cancer (CRC) rarely metastasizes to the skin, it is an important cause of cutaneous metastasis due to its high incidence in the general population. When it does spread to the skin, CRC preferentially affects the abdominal wall. Lesions typically resemble the primary tumor but may appear anaplastic. The occurrence of cutaneous metastasis suggests latestage disease and carries a poor prognosis.²⁴

Merkel cell carcinoma and melanoma are aggressive skin cancers with high mortality rates. The former is rarer but more lethal. Merkel cell carcinomas typically occur in elderly white men on sun-exposed areas of the skin. Tumors present as asymptomatic, rapidly expanding, blue-red, firm nodules. Immunosuppression and UV light exposure are notable risk factors.²⁵ Of the 4 major subtypes of cutaneous melanoma, superficial spreading is the most common, followed by nodular, lentigo maligna, and acral lentiginous.²⁶ Superficial spreading melanoma characteristically presents as an expanding asymmetric macule or thin plaque with irregular borders and variation in size and color (black, brown, or red). Nodular melanoma usually presents as symmetric in shape and color (amelanotic, black, or brown). Early recognition by both the patient and clinician is essential in preventing tumor growth and progression.²⁷

Our patient’s presentation was highly concerning for cutaneous metastasis given her history of CRC. Furthermore, the finding of severe anemia was atypical for skin cancer and more characteristic of the prior malignancy. Imaging revealed a locally confined mass with no evidence of extension, lymph node involvement, or additional lesions. The diagnosis was clinched with histopathologic examination.

The Diagnosis: Histiocytoid Sweet Syndrome

The patient was admitted for clinical study and treatment monitoring. During the first 72 hours of admittance, the lesions and general malaise further developed along with C-reactive protein elevation (126 mg/L). Administration of intravenous prednisone at a dosage of 1 mg/kg daily was accompanied by substantial improvement after 1 week of treatment, with subsequent follow-up and outpatient monitoring. An underlying neoplasia was ruled out after review of medical history, physical examination, complete blood cell count, chest radiography, abdominal ultrasonography, colonoscopy, and bone marrow aspiration.

A 4-mm skin biopsy was performed from a lesion on the neck (Figure 1). Histology revealed a dermis with prominent edema alongside superficial, deep, and periadnexal perivascular inflammatory infiltrates, as well as predominant lymphocytes and cells with a histiocytoid profile (Figure 2). These findings were accompanied by isolated neutrophil foci. The absence of leukocytoclastic vasculitis was noted. Immunohistochemistry demonstrated that the histiocyte population was positive for myeloperoxidase and CD68, which categorized them as immature cells of myeloid origin (Figure 3). Clinical and histopathologic findings led to a definitive diagnosis of histiocytoid Sweet syndrome (SS). Sweet syndrome consists of a neutrophilic dermatosis profile. Clinically, it manifests as a sudden onset of painful nodules and plaques accompanied by fever, malaise, and leukocytosis.

Histiocytoid SS is a rare histologic variant of SS initially described by Requena et al1 in 2005. In histiocytoid SS, the main inflammatory infiltrates are promyelocytes and myelocytes.² Immunohistochemistry shows positivity for myeloperoxidase, CD15, CD43, CD45, CD68, MAC-386, and HAM56.¹ The diagnosis is determined by exclusion after adequate clinical and histopathologic correlation, which also should exclude other diagnoses such as leukemia cutis and interstitial granulomatous dermatitis.³ Histiocytoid SS may be related to an increased risk for underlying malignancy. Haber et al⁴ performed a systematic review in which they concluded that approximately 40% of patients newly diagnosed with histiocytoid SS subsequently were diagnosed or already were diagnosed with a hematologic or solid cancer vs 21% in the classical neutrophilic infiltrate of SS (NSS). Histiocytoid SS more commonly was associated with myelodysplastic syndrome (46% vs 2.5% in NSS) and hematologic malignancies (42.5% vs 25% in SS).

The initial differential diagnoses include inflammatory dermatoses, infections, neoplasms, and systemic diseases. In exudative erythema multiforme, early lesions are composed of typical target lesions with mucosal involvement in 25% to 60% of patients.⁵ Erythema elevatum diutinum is a chronic dermatosis characterized by asymptomatic papules and red-violet nodules. The most characteristic histologic finding is leukocytoclastic vasculitis.⁶ The absence of vasculitis is part of the major diagnostic criteria for SS.⁷ Wells syndrome is associated with general malaise, and edematous and erythematous-violet plaques or nodules appear on the limbs; however, it frequently is associated with eosinophilia in peripheral blood, and histology shows that the main cell population of the inflammatory infiltrate also is eosinophilic.⁸ Painful, superficial, and erosive blisters appear preferentially on the face and backs of the arms in bullous pyoderma gangrenosum. It usually is not associated with the typical systemic manifestations of SS (ie, fever, arthralgia, damage to target organs). On histopathology, the neutrophilic infiltrate is accompanied by subepidermal vesicles.⁹

Histiocytoid SS responds dramatically to corticosteroids. Other first-line treatments that avoid use of corticosteroids are colchicine, dapsone, and potassium iodide. Multiple treatments were attempted in our patient, including corticosteroids, methotrexate, dapsone, colchicine, and anakinra. Despite patients responding well to treatment, a possible underlying neoplasm, most frequently of hematologic origin, must be excluded.¹⁰

The Diagnosis: Histiocytoid Sweet Syndrome

The patient was admitted for clinical study and treatment monitoring. During the first 72 hours of admittance, the lesions and general malaise further developed along with C-reactive protein elevation (126 mg/L). Administration of intravenous prednisone at a dosage of 1 mg/kg daily was accompanied by substantial improvement after 1 week of treatment, with subsequent follow-up and outpatient monitoring. An underlying neoplasia was ruled out after review of medical history, physical examination, complete blood cell count, chest radiography, abdominal ultrasonography, colonoscopy, and bone marrow aspiration.

A 4-mm skin biopsy was performed from a lesion on the neck (Figure 1). Histology revealed a dermis with prominent edema alongside superficial, deep, and periadnexal perivascular inflammatory infiltrates, as well as predominant lymphocytes and cells with a histiocytoid profile (Figure 2). These findings were accompanied by isolated neutrophil foci. The absence of leukocytoclastic vasculitis was noted. Immunohistochemistry demonstrated that the histiocyte population was positive for myeloperoxidase and CD68, which categorized them as immature cells of myeloid origin (Figure 3). Clinical and histopathologic findings led to a definitive diagnosis of histiocytoid Sweet syndrome (SS). Sweet syndrome consists of a neutrophilic dermatosis profile. Clinically, it manifests as a sudden onset of painful nodules and plaques accompanied by fever, malaise, and leukocytosis.

Histiocytoid SS is a rare histologic variant of SS initially described by Requena et al1 in 2005. In histiocytoid SS, the main inflammatory infiltrates are promyelocytes and myelocytes.² Immunohistochemistry shows positivity for myeloperoxidase, CD15, CD43, CD45, CD68, MAC-386, and HAM56.¹ The diagnosis is determined by exclusion after adequate clinical and histopathologic correlation, which also should exclude other diagnoses such as leukemia cutis and interstitial granulomatous dermatitis.³ Histiocytoid SS may be related to an increased risk for underlying malignancy. Haber et al⁴ performed a systematic review in which they concluded that approximately 40% of patients newly diagnosed with histiocytoid SS subsequently were diagnosed or already were diagnosed with a hematologic or solid cancer vs 21% in the classical neutrophilic infiltrate of SS (NSS). Histiocytoid SS more commonly was associated with myelodysplastic syndrome (46% vs 2.5% in NSS) and hematologic malignancies (42.5% vs 25% in SS).

The initial differential diagnoses include inflammatory dermatoses, infections, neoplasms, and systemic diseases. In exudative erythema multiforme, early lesions are composed of typical target lesions with mucosal involvement in 25% to 60% of patients.⁵ Erythema elevatum diutinum is a chronic dermatosis characterized by asymptomatic papules and red-violet nodules. The most characteristic histologic finding is leukocytoclastic vasculitis.⁶ The absence of vasculitis is part of the major diagnostic criteria for SS.⁷ Wells syndrome is associated with general malaise, and edematous and erythematous-violet plaques or nodules appear on the limbs; however, it frequently is associated with eosinophilia in peripheral blood, and histology shows that the main cell population of the inflammatory infiltrate also is eosinophilic.⁸ Painful, superficial, and erosive blisters appear preferentially on the face and backs of the arms in bullous pyoderma gangrenosum. It usually is not associated with the typical systemic manifestations of SS (ie, fever, arthralgia, damage to target organs). On histopathology, the neutrophilic infiltrate is accompanied by subepidermal vesicles.⁹

Histiocytoid SS responds dramatically to corticosteroids. Other first-line treatments that avoid use of corticosteroids are colchicine, dapsone, and potassium iodide. Multiple treatments were attempted in our patient, including corticosteroids, methotrexate, dapsone, colchicine, and anakinra. Despite patients responding well to treatment, a possible underlying neoplasm, most frequently of hematologic origin, must be excluded.¹⁰

The Diagnosis: Histiocytoid Sweet Syndrome

The patient was admitted for clinical study and treatment monitoring. During the first 72 hours of admittance, the lesions and general malaise further developed along with C-reactive protein elevation (126 mg/L). Administration of intravenous prednisone at a dosage of 1 mg/kg daily was accompanied by substantial improvement after 1 week of treatment, with subsequent follow-up and outpatient monitoring. An underlying neoplasia was ruled out after review of medical history, physical examination, complete blood cell count, chest radiography, abdominal ultrasonography, colonoscopy, and bone marrow aspiration.

A 4-mm skin biopsy was performed from a lesion on the neck (Figure 1). Histology revealed a dermis with prominent edema alongside superficial, deep, and periadnexal perivascular inflammatory infiltrates, as well as predominant lymphocytes and cells with a histiocytoid profile (Figure 2). These findings were accompanied by isolated neutrophil foci. The absence of leukocytoclastic vasculitis was noted. Immunohistochemistry demonstrated that the histiocyte population was positive for myeloperoxidase and CD68, which categorized them as immature cells of myeloid origin (Figure 3). Clinical and histopathologic findings led to a definitive diagnosis of histiocytoid Sweet syndrome (SS). Sweet syndrome consists of a neutrophilic dermatosis profile. Clinically, it manifests as a sudden onset of painful nodules and plaques accompanied by fever, malaise, and leukocytosis.

Histiocytoid SS is a rare histologic variant of SS initially described by Requena et al1 in 2005. In histiocytoid SS, the main inflammatory infiltrates are promyelocytes and myelocytes.² Immunohistochemistry shows positivity for myeloperoxidase, CD15, CD43, CD45, CD68, MAC-386, and HAM56.¹ The diagnosis is determined by exclusion after adequate clinical and histopathologic correlation, which also should exclude other diagnoses such as leukemia cutis and interstitial granulomatous dermatitis.³ Histiocytoid SS may be related to an increased risk for underlying malignancy. Haber et al⁴ performed a systematic review in which they concluded that approximately 40% of patients newly diagnosed with histiocytoid SS subsequently were diagnosed or already were diagnosed with a hematologic or solid cancer vs 21% in the classical neutrophilic infiltrate of SS (NSS). Histiocytoid SS more commonly was associated with myelodysplastic syndrome (46% vs 2.5% in NSS) and hematologic malignancies (42.5% vs 25% in SS).

The initial differential diagnoses include inflammatory dermatoses, infections, neoplasms, and systemic diseases. In exudative erythema multiforme, early lesions are composed of typical target lesions with mucosal involvement in 25% to 60% of patients.⁵ Erythema elevatum diutinum is a chronic dermatosis characterized by asymptomatic papules and red-violet nodules. The most characteristic histologic finding is leukocytoclastic vasculitis.⁶ The absence of vasculitis is part of the major diagnostic criteria for SS.⁷ Wells syndrome is associated with general malaise, and edematous and erythematous-violet plaques or nodules appear on the limbs; however, it frequently is associated with eosinophilia in peripheral blood, and histology shows that the main cell population of the inflammatory infiltrate also is eosinophilic.⁸ Painful, superficial, and erosive blisters appear preferentially on the face and backs of the arms in bullous pyoderma gangrenosum. It usually is not associated with the typical systemic manifestations of SS (ie, fever, arthralgia, damage to target organs). On histopathology, the neutrophilic infiltrate is accompanied by subepidermal vesicles.⁹

Histiocytoid SS responds dramatically to corticosteroids. Other first-line treatments that avoid use of corticosteroids are colchicine, dapsone, and potassium iodide. Multiple treatments were attempted in our patient, including corticosteroids, methotrexate, dapsone, colchicine, and anakinra. Despite patients responding well to treatment, a possible underlying neoplasm, most frequently of hematologic origin, must be excluded.¹⁰

The Diagnosis: Kaposi Sarcoma

A punch biopsy of a lesion on the right side of the back revealed a diffuse, poorly circumscribed, spindle cell neoplasm of the papillary and reticular dermis with associated vascular and pseudovascular spaces distended by erythrocytes (Figure 1). Immunostaining was positive for human herpesvirus 8 (HHV-8)(Figure 2), ETS-related gene, CD31, and CD34 and negative for pan cytokeratin, confirming the diagnosis of Kaposi sarcoma (KS). Bacterial, fungal, and mycobacterial tissue cultures were negative. The patient was tested for HIV and referred to infectious disease and oncology. He subsequently was found to have HIV with a viral load greater than 1 million copies. He was started on antiretroviral therapy and Pneumocystis jirovecii pneumonia prophylaxis. Computed tomography of the chest, abdomen, and pelvis showed bilateral, multifocal, perihilar, flame-shaped consolidations suggestive of KS. The patient later disclosed having an intermittent dry cough of more than a year’s duration with occasional bright red blood per rectum after bowel movements. After workup, the patient was found to have cytomegalovirus esophagitis/gastritis and candidal esophagitis that were treated with valganciclovir and fluconazole, respectively.

Kaposi sarcoma is an angioproliferative, AIDSdefining disease associated with HHV-8. There are 4 types of KS as defined by the populations they affect. AIDS-associated KS occurs in individuals with HIV, as seen in our patient. It often is accompanied by extensive mucocutaneous and visceral lesions, as well as systemic symptoms such as fever, weight loss, and diarrhea.¹ Classic KS is a variant that presents in older men of Mediterranean, Eastern European, and South American descent. Cutaneous lesions typically are distributed on the lower extremities.^2,3 Endemic (African) KS is seen in HIV-negative children and young adults in equatorial Africa. It most commonly affects the lower extremities or lymph nodes and usually follows a more aggressive course.² Lastly, iatrogenic KS is associated with immunosuppressive medications or conditions, such as organ transplantation, chemotherapy, and rheumatologic disorders.^3,4

Kaposi sarcoma commonly presents as violaceous or dark red macules, patches, papules, plaques, and nodules on various parts of the body (Figure 3). Lesions typically begin as macules and progress into plaques or nodules. Our patient presented as a deceptively healthy young man with lesions at various stages of development. In addition to the skin and oral mucosa, the lungs, lymph nodes, and gastrointestinal tract commonly are involved in AIDS-associated KS.⁵ Patients may experience symptoms of internal involvement, including bleeding, hematochezia, odynophagia, or dyspnea.

The differential diagnosis includes conditions that can mimic KS, including bacillary angiomatosis, angioinvasive fungal disease, sarcoid, and other malignancies. A skin biopsy is the gold standard for definitive diagnosis of KS. Histopathology shows a vascular proliferation in the dermis and spindle cell proliferation.⁶ Kaposi sarcoma stains positively for factor VIII–related antigen, CD31, and CD34.² Additionally, staining for HHV-8 gene products, such as latency-associated nuclear antigen 1, is helpful in differentiating KS from other conditions.⁷

In HIV-associated KS, the mainstay of treatment is initiation of highly active antiretroviral therapy. Typically, as the CD4 count rises with treatment, the tumor burden classic KS, effective treatment options include recurrent cryotherapy or intralesional chemotherapeutics, such as vincristine, for localized lesions; for widespread disease, pegylated liposomal doxorubicin or radiation have been found to be effective options. Lastly, for patients with iatrogenic KS, reducing immunosuppressive medications is a reasonable first step in management. If this does not yield adequate improvement, transitioning from calcineurin inhibitors (eg, cyclosporine) to proliferation signal inhibitors (eg, sirolimus) may lead to resolution.⁷

The Diagnosis: Kaposi Sarcoma

A punch biopsy of a lesion on the right side of the back revealed a diffuse, poorly circumscribed, spindle cell neoplasm of the papillary and reticular dermis with associated vascular and pseudovascular spaces distended by erythrocytes (Figure 1). Immunostaining was positive for human herpesvirus 8 (HHV-8)(Figure 2), ETS-related gene, CD31, and CD34 and negative for pan cytokeratin, confirming the diagnosis of Kaposi sarcoma (KS). Bacterial, fungal, and mycobacterial tissue cultures were negative. The patient was tested for HIV and referred to infectious disease and oncology. He subsequently was found to have HIV with a viral load greater than 1 million copies. He was started on antiretroviral therapy and Pneumocystis jirovecii pneumonia prophylaxis. Computed tomography of the chest, abdomen, and pelvis showed bilateral, multifocal, perihilar, flame-shaped consolidations suggestive of KS. The patient later disclosed having an intermittent dry cough of more than a year’s duration with occasional bright red blood per rectum after bowel movements. After workup, the patient was found to have cytomegalovirus esophagitis/gastritis and candidal esophagitis that were treated with valganciclovir and fluconazole, respectively.

Kaposi sarcoma is an angioproliferative, AIDSdefining disease associated with HHV-8. There are 4 types of KS as defined by the populations they affect. AIDS-associated KS occurs in individuals with HIV, as seen in our patient. It often is accompanied by extensive mucocutaneous and visceral lesions, as well as systemic symptoms such as fever, weight loss, and diarrhea.¹ Classic KS is a variant that presents in older men of Mediterranean, Eastern European, and South American descent. Cutaneous lesions typically are distributed on the lower extremities.^2,3 Endemic (African) KS is seen in HIV-negative children and young adults in equatorial Africa. It most commonly affects the lower extremities or lymph nodes and usually follows a more aggressive course.² Lastly, iatrogenic KS is associated with immunosuppressive medications or conditions, such as organ transplantation, chemotherapy, and rheumatologic disorders.^3,4

Kaposi sarcoma commonly presents as violaceous or dark red macules, patches, papules, plaques, and nodules on various parts of the body (Figure 3). Lesions typically begin as macules and progress into plaques or nodules. Our patient presented as a deceptively healthy young man with lesions at various stages of development. In addition to the skin and oral mucosa, the lungs, lymph nodes, and gastrointestinal tract commonly are involved in AIDS-associated KS.⁵ Patients may experience symptoms of internal involvement, including bleeding, hematochezia, odynophagia, or dyspnea.

The differential diagnosis includes conditions that can mimic KS, including bacillary angiomatosis, angioinvasive fungal disease, sarcoid, and other malignancies. A skin biopsy is the gold standard for definitive diagnosis of KS. Histopathology shows a vascular proliferation in the dermis and spindle cell proliferation.⁶ Kaposi sarcoma stains positively for factor VIII–related antigen, CD31, and CD34.² Additionally, staining for HHV-8 gene products, such as latency-associated nuclear antigen 1, is helpful in differentiating KS from other conditions.⁷

In HIV-associated KS, the mainstay of treatment is initiation of highly active antiretroviral therapy. Typically, as the CD4 count rises with treatment, the tumor burden classic KS, effective treatment options include recurrent cryotherapy or intralesional chemotherapeutics, such as vincristine, for localized lesions; for widespread disease, pegylated liposomal doxorubicin or radiation have been found to be effective options. Lastly, for patients with iatrogenic KS, reducing immunosuppressive medications is a reasonable first step in management. If this does not yield adequate improvement, transitioning from calcineurin inhibitors (eg, cyclosporine) to proliferation signal inhibitors (eg, sirolimus) may lead to resolution.⁷

The Diagnosis: Kaposi Sarcoma

A punch biopsy of a lesion on the right side of the back revealed a diffuse, poorly circumscribed, spindle cell neoplasm of the papillary and reticular dermis with associated vascular and pseudovascular spaces distended by erythrocytes (Figure 1). Immunostaining was positive for human herpesvirus 8 (HHV-8)(Figure 2), ETS-related gene, CD31, and CD34 and negative for pan cytokeratin, confirming the diagnosis of Kaposi sarcoma (KS). Bacterial, fungal, and mycobacterial tissue cultures were negative. The patient was tested for HIV and referred to infectious disease and oncology. He subsequently was found to have HIV with a viral load greater than 1 million copies. He was started on antiretroviral therapy and Pneumocystis jirovecii pneumonia prophylaxis. Computed tomography of the chest, abdomen, and pelvis showed bilateral, multifocal, perihilar, flame-shaped consolidations suggestive of KS. The patient later disclosed having an intermittent dry cough of more than a year’s duration with occasional bright red blood per rectum after bowel movements. After workup, the patient was found to have cytomegalovirus esophagitis/gastritis and candidal esophagitis that were treated with valganciclovir and fluconazole, respectively.

Kaposi sarcoma is an angioproliferative, AIDSdefining disease associated with HHV-8. There are 4 types of KS as defined by the populations they affect. AIDS-associated KS occurs in individuals with HIV, as seen in our patient. It often is accompanied by extensive mucocutaneous and visceral lesions, as well as systemic symptoms such as fever, weight loss, and diarrhea.¹ Classic KS is a variant that presents in older men of Mediterranean, Eastern European, and South American descent. Cutaneous lesions typically are distributed on the lower extremities.^2,3 Endemic (African) KS is seen in HIV-negative children and young adults in equatorial Africa. It most commonly affects the lower extremities or lymph nodes and usually follows a more aggressive course.² Lastly, iatrogenic KS is associated with immunosuppressive medications or conditions, such as organ transplantation, chemotherapy, and rheumatologic disorders.^3,4

Kaposi sarcoma commonly presents as violaceous or dark red macules, patches, papules, plaques, and nodules on various parts of the body (Figure 3). Lesions typically begin as macules and progress into plaques or nodules. Our patient presented as a deceptively healthy young man with lesions at various stages of development. In addition to the skin and oral mucosa, the lungs, lymph nodes, and gastrointestinal tract commonly are involved in AIDS-associated KS.⁵ Patients may experience symptoms of internal involvement, including bleeding, hematochezia, odynophagia, or dyspnea.

The differential diagnosis includes conditions that can mimic KS, including bacillary angiomatosis, angioinvasive fungal disease, sarcoid, and other malignancies. A skin biopsy is the gold standard for definitive diagnosis of KS. Histopathology shows a vascular proliferation in the dermis and spindle cell proliferation.⁶ Kaposi sarcoma stains positively for factor VIII–related antigen, CD31, and CD34.² Additionally, staining for HHV-8 gene products, such as latency-associated nuclear antigen 1, is helpful in differentiating KS from other conditions.⁷

In HIV-associated KS, the mainstay of treatment is initiation of highly active antiretroviral therapy. Typically, as the CD4 count rises with treatment, the tumor burden classic KS, effective treatment options include recurrent cryotherapy or intralesional chemotherapeutics, such as vincristine, for localized lesions; for widespread disease, pegylated liposomal doxorubicin or radiation have been found to be effective options. Lastly, for patients with iatrogenic KS, reducing immunosuppressive medications is a reasonable first step in management. If this does not yield adequate improvement, transitioning from calcineurin inhibitors (eg, cyclosporine) to proliferation signal inhibitors (eg, sirolimus) may lead to resolution.⁷

The Diagnosis: Pemphigoid Gestationis

A lesional biopsy showed a subepidermal split with eosinophils and neutrophils. Perilesional biopsy for direct immunofluorescence (DIF) showed linear deposition of 3+ C3 along the basement membrane zone. The clinical, histopathologic, and immunofluorescent findings were consistent with pemphigoid gestationis (PG). Prednisone 1 mg/kg daily was initiated. Her condition continued to worsen, and cyclosporine 250 mg daily was added while prednisone was tapered, with remission of disease.

Pemphigoid gestationis is an autoimmune bullous dermatosis that occurs in the second or third trimester of pregnancy, with an incidence of 1 in 50,000 to 60,000 pregnancies.¹ In terms of pathogenesis, aberrant expression of major histocompatibility complex class II molecules on placental tissues causes the loss of immune tolerance of the placenta, which leads to the production of antibodies against the placental protein bullous pemphigoid 180.² Bullous pemphigoid 180 also is a hemidesmosomal protein found in the skin of the mother; therefore, the presence of the circulating antibodies leads to separation at the dermoepidermal junction and vesiculation.

Pemphigoid gestationis is characterized by the sudden eruption of intensely pruritic urticarial papules and plaques, classically with periumbilical involvement. Tense vesicles and bullae can develop. Women with PG have an increased risk for development of Graves disease. Histopathology shows subepidermal vesiculation with a predominance of eosinophils. Direct immunofluorescence classically shows linear deposition of C3 along the basement membrane zone. Fetal complications include prematurity and small size for gestational age. Additionally, blisters can be seen in 5% to 10% of neonates due to placental transmission of autoantibodies.³

Frequently PG flares shortly postpartum. Pemphigoid gestationis resolves within 6 months postdelivery but frequently reoccurs in subsequent pregnancies. Mild disease can be treated with mid- to high-potency topical corticosteroids. Severe disease is managed with oral corticosteroids, most commonly prednisone. Refractory disease is managed with azathioprine, cyclosporine, intravenous immunoglobulin, or plasmapheresis.

The differential diagnosis of PG includes other pregnancy-associated dermatoses such as atopic eruption of pregnancy, impetigo herpetiformis, intrahepatic cholestasis of pregnancy, and polymorphous eruption of pregnancy. Atopic eruption of pregnancy is the most common dermatosis of pregnancy and is characterized by an eczematous eruption in patients with an atopic history, typically in the first trimester. Blisters are not seen, and DIF is negative. Impetigo herpetiformis, or pustular psoriasis of pregnancy, is a variant of generalized pustular psoriasis that occurs during pregnancy. Diffuse erythematous patches studded with pustules, rather than vesicles, are seen; DIF is negative. Intrahepatic cholestasis of pregnancy presents without primary skin findings and severe pruritus predominantly on the palms and soles, often with secondary excoriations. Polymorphous eruption of pregnancy presents as a polymorphous eruption of urticarial to erythematous papules and plaques commonly originating in striae. In contrast to PG, there is periumbilical sparing, vesiculation is rare, and DIF is negative.

The Diagnosis: Pemphigoid Gestationis

A lesional biopsy showed a subepidermal split with eosinophils and neutrophils. Perilesional biopsy for direct immunofluorescence (DIF) showed linear deposition of 3+ C3 along the basement membrane zone. The clinical, histopathologic, and immunofluorescent findings were consistent with pemphigoid gestationis (PG). Prednisone 1 mg/kg daily was initiated. Her condition continued to worsen, and cyclosporine 250 mg daily was added while prednisone was tapered, with remission of disease.

Pemphigoid gestationis is an autoimmune bullous dermatosis that occurs in the second or third trimester of pregnancy, with an incidence of 1 in 50,000 to 60,000 pregnancies.¹ In terms of pathogenesis, aberrant expression of major histocompatibility complex class II molecules on placental tissues causes the loss of immune tolerance of the placenta, which leads to the production of antibodies against the placental protein bullous pemphigoid 180.² Bullous pemphigoid 180 also is a hemidesmosomal protein found in the skin of the mother; therefore, the presence of the circulating antibodies leads to separation at the dermoepidermal junction and vesiculation.

Pemphigoid gestationis is characterized by the sudden eruption of intensely pruritic urticarial papules and plaques, classically with periumbilical involvement. Tense vesicles and bullae can develop. Women with PG have an increased risk for development of Graves disease. Histopathology shows subepidermal vesiculation with a predominance of eosinophils. Direct immunofluorescence classically shows linear deposition of C3 along the basement membrane zone. Fetal complications include prematurity and small size for gestational age. Additionally, blisters can be seen in 5% to 10% of neonates due to placental transmission of autoantibodies.³

Frequently PG flares shortly postpartum. Pemphigoid gestationis resolves within 6 months postdelivery but frequently reoccurs in subsequent pregnancies. Mild disease can be treated with mid- to high-potency topical corticosteroids. Severe disease is managed with oral corticosteroids, most commonly prednisone. Refractory disease is managed with azathioprine, cyclosporine, intravenous immunoglobulin, or plasmapheresis.

The differential diagnosis of PG includes other pregnancy-associated dermatoses such as atopic eruption of pregnancy, impetigo herpetiformis, intrahepatic cholestasis of pregnancy, and polymorphous eruption of pregnancy. Atopic eruption of pregnancy is the most common dermatosis of pregnancy and is characterized by an eczematous eruption in patients with an atopic history, typically in the first trimester. Blisters are not seen, and DIF is negative. Impetigo herpetiformis, or pustular psoriasis of pregnancy, is a variant of generalized pustular psoriasis that occurs during pregnancy. Diffuse erythematous patches studded with pustules, rather than vesicles, are seen; DIF is negative. Intrahepatic cholestasis of pregnancy presents without primary skin findings and severe pruritus predominantly on the palms and soles, often with secondary excoriations. Polymorphous eruption of pregnancy presents as a polymorphous eruption of urticarial to erythematous papules and plaques commonly originating in striae. In contrast to PG, there is periumbilical sparing, vesiculation is rare, and DIF is negative.

The Diagnosis: Pemphigoid Gestationis

A lesional biopsy showed a subepidermal split with eosinophils and neutrophils. Perilesional biopsy for direct immunofluorescence (DIF) showed linear deposition of 3+ C3 along the basement membrane zone. The clinical, histopathologic, and immunofluorescent findings were consistent with pemphigoid gestationis (PG). Prednisone 1 mg/kg daily was initiated. Her condition continued to worsen, and cyclosporine 250 mg daily was added while prednisone was tapered, with remission of disease.

Pemphigoid gestationis is an autoimmune bullous dermatosis that occurs in the second or third trimester of pregnancy, with an incidence of 1 in 50,000 to 60,000 pregnancies.¹ In terms of pathogenesis, aberrant expression of major histocompatibility complex class II molecules on placental tissues causes the loss of immune tolerance of the placenta, which leads to the production of antibodies against the placental protein bullous pemphigoid 180.² Bullous pemphigoid 180 also is a hemidesmosomal protein found in the skin of the mother; therefore, the presence of the circulating antibodies leads to separation at the dermoepidermal junction and vesiculation.

Pemphigoid gestationis is characterized by the sudden eruption of intensely pruritic urticarial papules and plaques, classically with periumbilical involvement. Tense vesicles and bullae can develop. Women with PG have an increased risk for development of Graves disease. Histopathology shows subepidermal vesiculation with a predominance of eosinophils. Direct immunofluorescence classically shows linear deposition of C3 along the basement membrane zone. Fetal complications include prematurity and small size for gestational age. Additionally, blisters can be seen in 5% to 10% of neonates due to placental transmission of autoantibodies.³

Frequently PG flares shortly postpartum. Pemphigoid gestationis resolves within 6 months postdelivery but frequently reoccurs in subsequent pregnancies. Mild disease can be treated with mid- to high-potency topical corticosteroids. Severe disease is managed with oral corticosteroids, most commonly prednisone. Refractory disease is managed with azathioprine, cyclosporine, intravenous immunoglobulin, or plasmapheresis.

The differential diagnosis of PG includes other pregnancy-associated dermatoses such as atopic eruption of pregnancy, impetigo herpetiformis, intrahepatic cholestasis of pregnancy, and polymorphous eruption of pregnancy. Atopic eruption of pregnancy is the most common dermatosis of pregnancy and is characterized by an eczematous eruption in patients with an atopic history, typically in the first trimester. Blisters are not seen, and DIF is negative. Impetigo herpetiformis, or pustular psoriasis of pregnancy, is a variant of generalized pustular psoriasis that occurs during pregnancy. Diffuse erythematous patches studded with pustules, rather than vesicles, are seen; DIF is negative. Intrahepatic cholestasis of pregnancy presents without primary skin findings and severe pruritus predominantly on the palms and soles, often with secondary excoriations. Polymorphous eruption of pregnancy presents as a polymorphous eruption of urticarial to erythematous papules and plaques commonly originating in striae. In contrast to PG, there is periumbilical sparing, vesiculation is rare, and DIF is negative.

The Diagnosis: Gamasoidosis

An entomologist confirmed the specimen as an avian mite in either the Dermanyssus or Ornithonyssus genera (quiz image [bottom]). The patient was asked whether any bird had nested around her bedroom, and she affirmed that a woodpecker had nested outside her bedroom closet that spring. She subsequently discovered it had burrowed a hole into her closet wall. She and her husband removed the nest, and within 4 weeks, the eruption permanently cleared.

Gamasoidosis, or avian mite dermatitis, often is an overlooked, difficult-to-make diagnosis that is increasing in prevalence.¹ Bird mites are ectoparasitic arthropods that are 0.3 to 1 mm in length. They have egg-shaped bodies with 4 pairs of legs; they are a translucent brown color before feeding and red after feeding.² Although most avian mites cannot subsist off human blood, if the mites are without an avian host, such as after affected birds abandon their nests, the mites will bite humans.³ Studies have discovered the presence of mammalian erythrocytes in the digestive tracts of one species of bird mite, Dermanyssus gallinae, suggesting that at least one form of avian mite may feed off humans but typically cannot reproduce without an avian blood meal.⁴ Individuals with gamasoidosis often are exposed to avian mites by owning birds as pets, rearing chickens or messenger pigeons, or having bird’s nests around their bedrooms or air conditioning units.¹

Most people who develop avian mite dermatitis are the only affected member of the family to develop pruritus and papules since the reaction requires both bites and hypersensitivity to them; however, there are cases of nuclear families all reacting to avian mite bites.^2,4 As in this case, hypersensitivity to avian mite bites causes exquisitely pruritic 2- to 5-mm papules, vesicles, or urticarial lesions that may be diagnosed as papular urticaria or misdiagnosed as scabies. Although bird mites may carry bacteria such as Salmonella, Spirochaete, Rickettsia, and Pasteurella, they have not demonstrated an ability to pass these on to human vectors.^5,6

Bird mites will spend most of their lives on avian hosts but can spread to humans through direct contact or through air.⁷ Mites can go through floors, walls, ceilings, or most commonly through ventilation or air conditioning units. Increasing urbanization, especially in warmer climates where avian mites thrive, has increased the prevalence of gamasoidosis.¹

Avian mite dermatitis commonly can be mistaken for scabies, but the mites can be seen with the naked eye and cannot form burrows, unlike scabies.^4,8 Avian mites usually are not found on human skin since they leave the host after feeding and move with surprising speed.⁸ Pediculosis corporis (body lice) results from an infestation of Pediculus humanus corporis. At 2- to 4-mm long, this louse is much larger than a bird mite. Body lice rarely are found on the skin but rather live and lay eggs on clothing, particularly along the seams. The body louse has an elongated body with 3 segments and short antennae. Pthirus pubis (pubic lice) measure 1.5 to 2.0 mm in adulthood and have wider, more crablike bodies compared to body or hair lice or avian mites. Lice, being insects, have 6 legs as opposed to mites, being arachnids, having 8 legs. Cheyletiella are 0.5-mm long, nonburrowing mites commonly found on cats, dogs, and rabbits. Cheyletiella blakei affects cats. They look somewhat similar to bird mites but have hooklike palps extending from their heads instead of antennae.

Antihistamines and topical corticosteroids may reduce discomfort from avian bites but are not curative.^2,9 The most efficient way to treat gamasoidosis is to remove any affected birds or nearby bird’s nests, as the mites cannot survive more than a few weeks to months without feeding on an avian host.⁸ It also may be necessary to fumigate infested rooms.¹⁰

The diagnosis of avian mite dermatitis often is missed to the frustration of the patient and clinician alike. Becoming familiar with this bite reaction will help clinicians diagnose this dermatologic conundrum.

The Diagnosis: Gamasoidosis

An entomologist confirmed the specimen as an avian mite in either the Dermanyssus or Ornithonyssus genera (quiz image [bottom]). The patient was asked whether any bird had nested around her bedroom, and she affirmed that a woodpecker had nested outside her bedroom closet that spring. She subsequently discovered it had burrowed a hole into her closet wall. She and her husband removed the nest, and within 4 weeks, the eruption permanently cleared.

Gamasoidosis, or avian mite dermatitis, often is an overlooked, difficult-to-make diagnosis that is increasing in prevalence.¹ Bird mites are ectoparasitic arthropods that are 0.3 to 1 mm in length. They have egg-shaped bodies with 4 pairs of legs; they are a translucent brown color before feeding and red after feeding.² Although most avian mites cannot subsist off human blood, if the mites are without an avian host, such as after affected birds abandon their nests, the mites will bite humans.³ Studies have discovered the presence of mammalian erythrocytes in the digestive tracts of one species of bird mite, Dermanyssus gallinae, suggesting that at least one form of avian mite may feed off humans but typically cannot reproduce without an avian blood meal.⁴ Individuals with gamasoidosis often are exposed to avian mites by owning birds as pets, rearing chickens or messenger pigeons, or having bird’s nests around their bedrooms or air conditioning units.¹

Most people who develop avian mite dermatitis are the only affected member of the family to develop pruritus and papules since the reaction requires both bites and hypersensitivity to them; however, there are cases of nuclear families all reacting to avian mite bites.^2,4 As in this case, hypersensitivity to avian mite bites causes exquisitely pruritic 2- to 5-mm papules, vesicles, or urticarial lesions that may be diagnosed as papular urticaria or misdiagnosed as scabies. Although bird mites may carry bacteria such as Salmonella, Spirochaete, Rickettsia, and Pasteurella, they have not demonstrated an ability to pass these on to human vectors.^5,6

Bird mites will spend most of their lives on avian hosts but can spread to humans through direct contact or through air.⁷ Mites can go through floors, walls, ceilings, or most commonly through ventilation or air conditioning units. Increasing urbanization, especially in warmer climates where avian mites thrive, has increased the prevalence of gamasoidosis.¹

Avian mite dermatitis commonly can be mistaken for scabies, but the mites can be seen with the naked eye and cannot form burrows, unlike scabies.^4,8 Avian mites usually are not found on human skin since they leave the host after feeding and move with surprising speed.⁸ Pediculosis corporis (body lice) results from an infestation of Pediculus humanus corporis. At 2- to 4-mm long, this louse is much larger than a bird mite. Body lice rarely are found on the skin but rather live and lay eggs on clothing, particularly along the seams. The body louse has an elongated body with 3 segments and short antennae. Pthirus pubis (pubic lice) measure 1.5 to 2.0 mm in adulthood and have wider, more crablike bodies compared to body or hair lice or avian mites. Lice, being insects, have 6 legs as opposed to mites, being arachnids, having 8 legs. Cheyletiella are 0.5-mm long, nonburrowing mites commonly found on cats, dogs, and rabbits. Cheyletiella blakei affects cats. They look somewhat similar to bird mites but have hooklike palps extending from their heads instead of antennae.

Antihistamines and topical corticosteroids may reduce discomfort from avian bites but are not curative.^2,9 The most efficient way to treat gamasoidosis is to remove any affected birds or nearby bird’s nests, as the mites cannot survive more than a few weeks to months without feeding on an avian host.⁸ It also may be necessary to fumigate infested rooms.¹⁰

The diagnosis of avian mite dermatitis often is missed to the frustration of the patient and clinician alike. Becoming familiar with this bite reaction will help clinicians diagnose this dermatologic conundrum.

The Diagnosis: Gamasoidosis

An entomologist confirmed the specimen as an avian mite in either the Dermanyssus or Ornithonyssus genera (quiz image [bottom]). The patient was asked whether any bird had nested around her bedroom, and she affirmed that a woodpecker had nested outside her bedroom closet that spring. She subsequently discovered it had burrowed a hole into her closet wall. She and her husband removed the nest, and within 4 weeks, the eruption permanently cleared.

Gamasoidosis, or avian mite dermatitis, often is an overlooked, difficult-to-make diagnosis that is increasing in prevalence.¹ Bird mites are ectoparasitic arthropods that are 0.3 to 1 mm in length. They have egg-shaped bodies with 4 pairs of legs; they are a translucent brown color before feeding and red after feeding.² Although most avian mites cannot subsist off human blood, if the mites are without an avian host, such as after affected birds abandon their nests, the mites will bite humans.³ Studies have discovered the presence of mammalian erythrocytes in the digestive tracts of one species of bird mite, Dermanyssus gallinae, suggesting that at least one form of avian mite may feed off humans but typically cannot reproduce without an avian blood meal.⁴ Individuals with gamasoidosis often are exposed to avian mites by owning birds as pets, rearing chickens or messenger pigeons, or having bird’s nests around their bedrooms or air conditioning units.¹

Most people who develop avian mite dermatitis are the only affected member of the family to develop pruritus and papules since the reaction requires both bites and hypersensitivity to them; however, there are cases of nuclear families all reacting to avian mite bites.^2,4 As in this case, hypersensitivity to avian mite bites causes exquisitely pruritic 2- to 5-mm papules, vesicles, or urticarial lesions that may be diagnosed as papular urticaria or misdiagnosed as scabies. Although bird mites may carry bacteria such as Salmonella, Spirochaete, Rickettsia, and Pasteurella, they have not demonstrated an ability to pass these on to human vectors.^5,6

Bird mites will spend most of their lives on avian hosts but can spread to humans through direct contact or through air.⁷ Mites can go through floors, walls, ceilings, or most commonly through ventilation or air conditioning units. Increasing urbanization, especially in warmer climates where avian mites thrive, has increased the prevalence of gamasoidosis.¹

Avian mite dermatitis commonly can be mistaken for scabies, but the mites can be seen with the naked eye and cannot form burrows, unlike scabies.^4,8 Avian mites usually are not found on human skin since they leave the host after feeding and move with surprising speed.⁸ Pediculosis corporis (body lice) results from an infestation of Pediculus humanus corporis. At 2- to 4-mm long, this louse is much larger than a bird mite. Body lice rarely are found on the skin but rather live and lay eggs on clothing, particularly along the seams. The body louse has an elongated body with 3 segments and short antennae. Pthirus pubis (pubic lice) measure 1.5 to 2.0 mm in adulthood and have wider, more crablike bodies compared to body or hair lice or avian mites. Lice, being insects, have 6 legs as opposed to mites, being arachnids, having 8 legs. Cheyletiella are 0.5-mm long, nonburrowing mites commonly found on cats, dogs, and rabbits. Cheyletiella blakei affects cats. They look somewhat similar to bird mites but have hooklike palps extending from their heads instead of antennae.

Antihistamines and topical corticosteroids may reduce discomfort from avian bites but are not curative.^2,9 The most efficient way to treat gamasoidosis is to remove any affected birds or nearby bird’s nests, as the mites cannot survive more than a few weeks to months without feeding on an avian host.⁸ It also may be necessary to fumigate infested rooms.¹⁰

The diagnosis of avian mite dermatitis often is missed to the frustration of the patient and clinician alike. Becoming familiar with this bite reaction will help clinicians diagnose this dermatologic conundrum.