Jason Jacob, MD

Eccrine carcinomas are uncommon cutaneous neoplasms demonstrating nonuniform histologic features, behavior, and nomenclature. Given the rarity of these tumors, no known criteria by which to diagnose the tumor or guidelines for treatment have been proposed. We report a rare case of an immunocompromised patient with a primary squamoid eccrine ductal carcinoma (SEDC) who was subsequently treated with radical resection and axillary dissection. It was later determined that the patient had distant metastasis of SEDC. A review of the literature on the diagnosis, treatment, and surveillance of SEDC also is provided.

Case Report

A 77-year-old man whose medical history was remarkable for chronic lymphocytic leukemia (CLL) and numerous previous basal cell carcinomas and squamous cell carcinomas (SCCs) presented with a 5-cm, stellate, sclerotic plaque on the left chest of approximately 2 years’ duration (Figure 1) and a 3-mm pink papule on the right nasal sidewall of 2 months’ duration. Initial histology of both lesions revealed carcinoma with squamous and ductal differentiation extending from the undersurface of the epidermis, favoring a diagnosis of SEDC (Figure 2). At the time of initial presentation, the patient also had a 6-mm pink papule on the right chest of several months duration that was consistent with a well-differentiated sebaceous carcinoma on histology.

Further analysis of the lesion on the left chest revealed positive staining for cytokeratin (CK) 5/14 and p63, suggestive of a cutaneous malignancy. Staining for S100 protein highlighted rare cells in the basal layer of tumor aggregates. The immunohistochemical profile showed negative staining for CK7, CK5D3, epithelial membrane antigen (EMA), estrogen receptor, progesterone receptor, and human epidermal growth factor 2.

Diagnosis of SEDC of the chest and nasal lesions was based on the morphologic architecture, which included ductal formation noted within the tumor. The chest lesion also had prominent squamoid differentiation. Another histologic feature consistent with SEDC was poorly demarcated, infiltrative neoplastic cells extending into the dermis and subcutis. Although there was some positive focal staining for carcinoembryonic antigen (CEA), variegation within the tumor and the prominent squamoid component might have contributed to this unexpected staining pattern.

The patient was admitted to the hospital for excision of the lesion on the chest wall. Initial workup revealed macrocytic anemia, which required transfusion, and an incidental finding of non–small-cell lung cancer. The chest lesion was unrelated to the non–small-cell lung cancer based on the staining profile. Material from the lung stained positive for thyroid transcription factor 1 (TTF-1) and exhibited rare staining for p63; however, the chest lesion did not stain positive for TTF-1 and had strong staining affinity for p63, indicative of a cutaneous malignancy.

The lesion on the chest wall was definitively excised. Pathologic analysis revealed a dermal-based infiltrative tumor of irregular nests and cords of squamoid cells with focal ductal formation in a fibromyxoid background stroma, suggestive of an adnexal carcinoma with a considerable degree of squamous differentiation and favoring a diagnosis of SEDC. Focal perineural invasion was noted, but no lymphovascular spread was identified; however, metastasis was identified in 1 of 26 axillary lymph nodes. The patient underwent 9 sessions of radiation therapy for the lung cancer and also was given cetuximab.

Three months later, the nasal tumor was subsequently excised in an outpatient procedure, and the final biopsy report indicated a diagnosis of basal cell carcinoma. One-and-a-half years later, in follow-up with surgery after removal of the chest lesion, a 2×3-cm mass was excised from the left neck that demonstrated lymph nodes consistent with metastatic SEDC. Careful evaluation of this patient, including family history and genetic screening, was considered. Our patient continues to follow-up with the dermatology department every 3 months. He has been doing well and has had multiple additional primary SCCs in the subsequent 5 years of follow-up.

Comment

Eccrine carcinoma is the most common subtype of adnexal carcinoma, representing 0.01% of all cutaneous tumors.¹ Squamoid eccrine ductal carcinoma is rare, with as few as 13 cases reported in the literature; 3 of these patients were treated with Mohs micrographic surgery (MMS).^1,2 Recently, two series of 7 and 30 cases, respectively, were longitudinally followed and described.^3,4 We report an additional rare case of SEDC in an immunocompromised patient with distant metastases that was treated with radical resection and axillary dissection.

Eccrine carcinoma is observed clinically as a slow-growing, nodular plaque on the scalp, arms, legs, or trunk in middle-aged and elderly individuals.¹ Squamoid eccrine ductal carcinoma also has been reported in a young woman.⁵ Another immunocompromised patient was identified in the literature with a great toe lesion that showed follicular differentiation along with the usual SEDC features of squamoid and ductal differentiation.⁶ The etiology of SEDC is controversial but is thought to be an SCC arising from eccrine glands, a subtype of eccrine carcinoma with extensive squamoid differentiation, or a biphenotypic carcinoma.^1,7

Histologically, SEDC is poorly circumscribed with an infiltrative growth pattern and deep extension into the dermis and subcutaneous tissue. The lesion is characterized by prominent squamous epithelial proliferation superficially with cellular atypia, keratinous cyst formation, squamous eddies, and eccrine ductal differentiation.¹

The differential diagnosis of SEDC includes SCC; metastatic carcinoma with squamoid features; and eccrine tumors, including eccrine poroma, microcystic adnexal carcinoma, and porocarcinoma with squamous differentiation.¹

Immunohistochemistry has a role in the diagnosis of SEDC. Findings include positive staining for S100 protein, EMA, CKs, and CEA. Glandular tissue stains positive for EMA and CEA, supporting an adnexal origin.¹ Positivity for p63 and CK5/6 supports the conclusion that this is a primary cutaneous malignancy, not a metastatic disease.¹

Squamoid eccrine ductal carcinoma has an indeterminate malignant potential. There is a disparity of clinical behavior between SCC and eccrine cancers; however, because squamous differentiation sometimes dominates the histological picture, eccrine carcinomas can be misdiagnosed as SCC.^1,8 Eccrine adnexal tumors are characterized by multiple local recurrences (70%–80% of cases); perineural invasion; and metastasis (50% of cases) to regional lymph nodes and viscera, including the lungs, liver, bones, and brain.¹ Squamous cell carcinoma, however, has a markedly lower recurrence rate (3.1%–18.7% of cases) and rate of metastasis (5.2%–37.8%).¹

Squamoid eccrine ductal carcinoma is classified as one of the less aggressive eccrine tumors, although the low number of cases makes it a controversial conclusion.¹ To our knowledge, no cases of SEDC metastasis have been reported with SEDC. Recurrence of SEDC has been reported locally, and perineural or perivascular invasion (or both) has been demonstrated in 3 cases.¹

Since SEDC has invasive and metastatic potential, as demonstrated in our case, along with elevated local recurrence rates, physicians must be able to properly diagnose this rare entity and recommend an appropriate surgical modality. Due to the low incidence of SEDC, there are no known randomized studies comparing treatment modalities.¹ Other works in the literature have suggested treating SEDC with the same approach as lesions with similar histologic features and behavior, such as eccrine carcinoma and SCC.^1,5-7

Surgical extirpation with complete margin examination is recommended, as SEDC tends to be underestimated in size, is aggressive in its infiltration, and is predisposed to perineural and perivascular invasion. The literature has shown that MMS has demonstrated lower recurrence rates (3.1%–5%) than other treatments at 5-year follow-up for SCC and (0%–5%) for eccrine carcinoma (average follow-up, 31 months).^1,5 Further studies are needed to understand the clinical progression of SEDC, and more experience is necessary with close follow-up of this subset of patients. Follow-up is determined at the present time from anecdotal experience and patient history.

Along with the rarity of SEDC in our patient, the simultaneous occurrence of 3 primary malignancies also is unusual. Patients with CLL have progressive defects of cell- and humoral-mediated immunity, causing immunosuppression. In a retrospective study, Tsimberidou et al⁹ reviewed the records of 2028 untreated CLL patients and determined that 27% had another primary malignancy, including skin (30%) and lung cancers (6%), which were two of the malignancies seen in our patient. The investigators concluded that patients with CLL have more than twice the risk of developing a second primary malignancy and an increased frequency of certain cancer types.⁹ Furthermore, treatment regimens for CLL have been considered to increase cell- and humoral-mediated immune defects at specific cancer sites,¹⁰ although the exact mechanism of this action is unknown. Development of a second primary malignancy (or even a third) in patients with SEDC is increasingly being reported in CLL patients.^9,10

A high index of suspicion with SEDC in the differential diagnosis should be maintained in elderly men with slow-growing, solitary, nodular lesions of the scalp, nose, arms, legs, or trunk.

Eccrine carcinomas are uncommon cutaneous neoplasms demonstrating nonuniform histologic features, behavior, and nomenclature. Given the rarity of these tumors, no known criteria by which to diagnose the tumor or guidelines for treatment have been proposed. We report a rare case of an immunocompromised patient with a primary squamoid eccrine ductal carcinoma (SEDC) who was subsequently treated with radical resection and axillary dissection. It was later determined that the patient had distant metastasis of SEDC. A review of the literature on the diagnosis, treatment, and surveillance of SEDC also is provided.

Case Report

A 77-year-old man whose medical history was remarkable for chronic lymphocytic leukemia (CLL) and numerous previous basal cell carcinomas and squamous cell carcinomas (SCCs) presented with a 5-cm, stellate, sclerotic plaque on the left chest of approximately 2 years’ duration (Figure 1) and a 3-mm pink papule on the right nasal sidewall of 2 months’ duration. Initial histology of both lesions revealed carcinoma with squamous and ductal differentiation extending from the undersurface of the epidermis, favoring a diagnosis of SEDC (Figure 2). At the time of initial presentation, the patient also had a 6-mm pink papule on the right chest of several months duration that was consistent with a well-differentiated sebaceous carcinoma on histology.

Further analysis of the lesion on the left chest revealed positive staining for cytokeratin (CK) 5/14 and p63, suggestive of a cutaneous malignancy. Staining for S100 protein highlighted rare cells in the basal layer of tumor aggregates. The immunohistochemical profile showed negative staining for CK7, CK5D3, epithelial membrane antigen (EMA), estrogen receptor, progesterone receptor, and human epidermal growth factor 2.

Diagnosis of SEDC of the chest and nasal lesions was based on the morphologic architecture, which included ductal formation noted within the tumor. The chest lesion also had prominent squamoid differentiation. Another histologic feature consistent with SEDC was poorly demarcated, infiltrative neoplastic cells extending into the dermis and subcutis. Although there was some positive focal staining for carcinoembryonic antigen (CEA), variegation within the tumor and the prominent squamoid component might have contributed to this unexpected staining pattern.

The patient was admitted to the hospital for excision of the lesion on the chest wall. Initial workup revealed macrocytic anemia, which required transfusion, and an incidental finding of non–small-cell lung cancer. The chest lesion was unrelated to the non–small-cell lung cancer based on the staining profile. Material from the lung stained positive for thyroid transcription factor 1 (TTF-1) and exhibited rare staining for p63; however, the chest lesion did not stain positive for TTF-1 and had strong staining affinity for p63, indicative of a cutaneous malignancy.

The lesion on the chest wall was definitively excised. Pathologic analysis revealed a dermal-based infiltrative tumor of irregular nests and cords of squamoid cells with focal ductal formation in a fibromyxoid background stroma, suggestive of an adnexal carcinoma with a considerable degree of squamous differentiation and favoring a diagnosis of SEDC. Focal perineural invasion was noted, but no lymphovascular spread was identified; however, metastasis was identified in 1 of 26 axillary lymph nodes. The patient underwent 9 sessions of radiation therapy for the lung cancer and also was given cetuximab.

Three months later, the nasal tumor was subsequently excised in an outpatient procedure, and the final biopsy report indicated a diagnosis of basal cell carcinoma. One-and-a-half years later, in follow-up with surgery after removal of the chest lesion, a 2×3-cm mass was excised from the left neck that demonstrated lymph nodes consistent with metastatic SEDC. Careful evaluation of this patient, including family history and genetic screening, was considered. Our patient continues to follow-up with the dermatology department every 3 months. He has been doing well and has had multiple additional primary SCCs in the subsequent 5 years of follow-up.

Comment

Eccrine carcinoma is the most common subtype of adnexal carcinoma, representing 0.01% of all cutaneous tumors.¹ Squamoid eccrine ductal carcinoma is rare, with as few as 13 cases reported in the literature; 3 of these patients were treated with Mohs micrographic surgery (MMS).^1,2 Recently, two series of 7 and 30 cases, respectively, were longitudinally followed and described.^3,4 We report an additional rare case of SEDC in an immunocompromised patient with distant metastases that was treated with radical resection and axillary dissection.

Eccrine carcinoma is observed clinically as a slow-growing, nodular plaque on the scalp, arms, legs, or trunk in middle-aged and elderly individuals.¹ Squamoid eccrine ductal carcinoma also has been reported in a young woman.⁵ Another immunocompromised patient was identified in the literature with a great toe lesion that showed follicular differentiation along with the usual SEDC features of squamoid and ductal differentiation.⁶ The etiology of SEDC is controversial but is thought to be an SCC arising from eccrine glands, a subtype of eccrine carcinoma with extensive squamoid differentiation, or a biphenotypic carcinoma.^1,7

Histologically, SEDC is poorly circumscribed with an infiltrative growth pattern and deep extension into the dermis and subcutaneous tissue. The lesion is characterized by prominent squamous epithelial proliferation superficially with cellular atypia, keratinous cyst formation, squamous eddies, and eccrine ductal differentiation.¹

The differential diagnosis of SEDC includes SCC; metastatic carcinoma with squamoid features; and eccrine tumors, including eccrine poroma, microcystic adnexal carcinoma, and porocarcinoma with squamous differentiation.¹

Immunohistochemistry has a role in the diagnosis of SEDC. Findings include positive staining for S100 protein, EMA, CKs, and CEA. Glandular tissue stains positive for EMA and CEA, supporting an adnexal origin.¹ Positivity for p63 and CK5/6 supports the conclusion that this is a primary cutaneous malignancy, not a metastatic disease.¹

Squamoid eccrine ductal carcinoma has an indeterminate malignant potential. There is a disparity of clinical behavior between SCC and eccrine cancers; however, because squamous differentiation sometimes dominates the histological picture, eccrine carcinomas can be misdiagnosed as SCC.^1,8 Eccrine adnexal tumors are characterized by multiple local recurrences (70%–80% of cases); perineural invasion; and metastasis (50% of cases) to regional lymph nodes and viscera, including the lungs, liver, bones, and brain.¹ Squamous cell carcinoma, however, has a markedly lower recurrence rate (3.1%–18.7% of cases) and rate of metastasis (5.2%–37.8%).¹

Squamoid eccrine ductal carcinoma is classified as one of the less aggressive eccrine tumors, although the low number of cases makes it a controversial conclusion.¹ To our knowledge, no cases of SEDC metastasis have been reported with SEDC. Recurrence of SEDC has been reported locally, and perineural or perivascular invasion (or both) has been demonstrated in 3 cases.¹

Since SEDC has invasive and metastatic potential, as demonstrated in our case, along with elevated local recurrence rates, physicians must be able to properly diagnose this rare entity and recommend an appropriate surgical modality. Due to the low incidence of SEDC, there are no known randomized studies comparing treatment modalities.¹ Other works in the literature have suggested treating SEDC with the same approach as lesions with similar histologic features and behavior, such as eccrine carcinoma and SCC.^1,5-7

Surgical extirpation with complete margin examination is recommended, as SEDC tends to be underestimated in size, is aggressive in its infiltration, and is predisposed to perineural and perivascular invasion. The literature has shown that MMS has demonstrated lower recurrence rates (3.1%–5%) than other treatments at 5-year follow-up for SCC and (0%–5%) for eccrine carcinoma (average follow-up, 31 months).^1,5 Further studies are needed to understand the clinical progression of SEDC, and more experience is necessary with close follow-up of this subset of patients. Follow-up is determined at the present time from anecdotal experience and patient history.

Along with the rarity of SEDC in our patient, the simultaneous occurrence of 3 primary malignancies also is unusual. Patients with CLL have progressive defects of cell- and humoral-mediated immunity, causing immunosuppression. In a retrospective study, Tsimberidou et al⁹ reviewed the records of 2028 untreated CLL patients and determined that 27% had another primary malignancy, including skin (30%) and lung cancers (6%), which were two of the malignancies seen in our patient. The investigators concluded that patients with CLL have more than twice the risk of developing a second primary malignancy and an increased frequency of certain cancer types.⁹ Furthermore, treatment regimens for CLL have been considered to increase cell- and humoral-mediated immune defects at specific cancer sites,¹⁰ although the exact mechanism of this action is unknown. Development of a second primary malignancy (or even a third) in patients with SEDC is increasingly being reported in CLL patients.^9,10

A high index of suspicion with SEDC in the differential diagnosis should be maintained in elderly men with slow-growing, solitary, nodular lesions of the scalp, nose, arms, legs, or trunk.

Eccrine carcinomas are uncommon cutaneous neoplasms demonstrating nonuniform histologic features, behavior, and nomenclature. Given the rarity of these tumors, no known criteria by which to diagnose the tumor or guidelines for treatment have been proposed. We report a rare case of an immunocompromised patient with a primary squamoid eccrine ductal carcinoma (SEDC) who was subsequently treated with radical resection and axillary dissection. It was later determined that the patient had distant metastasis of SEDC. A review of the literature on the diagnosis, treatment, and surveillance of SEDC also is provided.

Case Report

A 77-year-old man whose medical history was remarkable for chronic lymphocytic leukemia (CLL) and numerous previous basal cell carcinomas and squamous cell carcinomas (SCCs) presented with a 5-cm, stellate, sclerotic plaque on the left chest of approximately 2 years’ duration (Figure 1) and a 3-mm pink papule on the right nasal sidewall of 2 months’ duration. Initial histology of both lesions revealed carcinoma with squamous and ductal differentiation extending from the undersurface of the epidermis, favoring a diagnosis of SEDC (Figure 2). At the time of initial presentation, the patient also had a 6-mm pink papule on the right chest of several months duration that was consistent with a well-differentiated sebaceous carcinoma on histology.

Further analysis of the lesion on the left chest revealed positive staining for cytokeratin (CK) 5/14 and p63, suggestive of a cutaneous malignancy. Staining for S100 protein highlighted rare cells in the basal layer of tumor aggregates. The immunohistochemical profile showed negative staining for CK7, CK5D3, epithelial membrane antigen (EMA), estrogen receptor, progesterone receptor, and human epidermal growth factor 2.

Diagnosis of SEDC of the chest and nasal lesions was based on the morphologic architecture, which included ductal formation noted within the tumor. The chest lesion also had prominent squamoid differentiation. Another histologic feature consistent with SEDC was poorly demarcated, infiltrative neoplastic cells extending into the dermis and subcutis. Although there was some positive focal staining for carcinoembryonic antigen (CEA), variegation within the tumor and the prominent squamoid component might have contributed to this unexpected staining pattern.

The patient was admitted to the hospital for excision of the lesion on the chest wall. Initial workup revealed macrocytic anemia, which required transfusion, and an incidental finding of non–small-cell lung cancer. The chest lesion was unrelated to the non–small-cell lung cancer based on the staining profile. Material from the lung stained positive for thyroid transcription factor 1 (TTF-1) and exhibited rare staining for p63; however, the chest lesion did not stain positive for TTF-1 and had strong staining affinity for p63, indicative of a cutaneous malignancy.

The lesion on the chest wall was definitively excised. Pathologic analysis revealed a dermal-based infiltrative tumor of irregular nests and cords of squamoid cells with focal ductal formation in a fibromyxoid background stroma, suggestive of an adnexal carcinoma with a considerable degree of squamous differentiation and favoring a diagnosis of SEDC. Focal perineural invasion was noted, but no lymphovascular spread was identified; however, metastasis was identified in 1 of 26 axillary lymph nodes. The patient underwent 9 sessions of radiation therapy for the lung cancer and also was given cetuximab.

Three months later, the nasal tumor was subsequently excised in an outpatient procedure, and the final biopsy report indicated a diagnosis of basal cell carcinoma. One-and-a-half years later, in follow-up with surgery after removal of the chest lesion, a 2×3-cm mass was excised from the left neck that demonstrated lymph nodes consistent with metastatic SEDC. Careful evaluation of this patient, including family history and genetic screening, was considered. Our patient continues to follow-up with the dermatology department every 3 months. He has been doing well and has had multiple additional primary SCCs in the subsequent 5 years of follow-up.

Comment

Eccrine carcinoma is the most common subtype of adnexal carcinoma, representing 0.01% of all cutaneous tumors.¹ Squamoid eccrine ductal carcinoma is rare, with as few as 13 cases reported in the literature; 3 of these patients were treated with Mohs micrographic surgery (MMS).^1,2 Recently, two series of 7 and 30 cases, respectively, were longitudinally followed and described.^3,4 We report an additional rare case of SEDC in an immunocompromised patient with distant metastases that was treated with radical resection and axillary dissection.

Eccrine carcinoma is observed clinically as a slow-growing, nodular plaque on the scalp, arms, legs, or trunk in middle-aged and elderly individuals.¹ Squamoid eccrine ductal carcinoma also has been reported in a young woman.⁵ Another immunocompromised patient was identified in the literature with a great toe lesion that showed follicular differentiation along with the usual SEDC features of squamoid and ductal differentiation.⁶ The etiology of SEDC is controversial but is thought to be an SCC arising from eccrine glands, a subtype of eccrine carcinoma with extensive squamoid differentiation, or a biphenotypic carcinoma.^1,7

Histologically, SEDC is poorly circumscribed with an infiltrative growth pattern and deep extension into the dermis and subcutaneous tissue. The lesion is characterized by prominent squamous epithelial proliferation superficially with cellular atypia, keratinous cyst formation, squamous eddies, and eccrine ductal differentiation.¹

The differential diagnosis of SEDC includes SCC; metastatic carcinoma with squamoid features; and eccrine tumors, including eccrine poroma, microcystic adnexal carcinoma, and porocarcinoma with squamous differentiation.¹

Immunohistochemistry has a role in the diagnosis of SEDC. Findings include positive staining for S100 protein, EMA, CKs, and CEA. Glandular tissue stains positive for EMA and CEA, supporting an adnexal origin.¹ Positivity for p63 and CK5/6 supports the conclusion that this is a primary cutaneous malignancy, not a metastatic disease.¹

Squamoid eccrine ductal carcinoma has an indeterminate malignant potential. There is a disparity of clinical behavior between SCC and eccrine cancers; however, because squamous differentiation sometimes dominates the histological picture, eccrine carcinomas can be misdiagnosed as SCC.^1,8 Eccrine adnexal tumors are characterized by multiple local recurrences (70%–80% of cases); perineural invasion; and metastasis (50% of cases) to regional lymph nodes and viscera, including the lungs, liver, bones, and brain.¹ Squamous cell carcinoma, however, has a markedly lower recurrence rate (3.1%–18.7% of cases) and rate of metastasis (5.2%–37.8%).¹

Squamoid eccrine ductal carcinoma is classified as one of the less aggressive eccrine tumors, although the low number of cases makes it a controversial conclusion.¹ To our knowledge, no cases of SEDC metastasis have been reported with SEDC. Recurrence of SEDC has been reported locally, and perineural or perivascular invasion (or both) has been demonstrated in 3 cases.¹

Since SEDC has invasive and metastatic potential, as demonstrated in our case, along with elevated local recurrence rates, physicians must be able to properly diagnose this rare entity and recommend an appropriate surgical modality. Due to the low incidence of SEDC, there are no known randomized studies comparing treatment modalities.¹ Other works in the literature have suggested treating SEDC with the same approach as lesions with similar histologic features and behavior, such as eccrine carcinoma and SCC.^1,5-7

Surgical extirpation with complete margin examination is recommended, as SEDC tends to be underestimated in size, is aggressive in its infiltration, and is predisposed to perineural and perivascular invasion. The literature has shown that MMS has demonstrated lower recurrence rates (3.1%–5%) than other treatments at 5-year follow-up for SCC and (0%–5%) for eccrine carcinoma (average follow-up, 31 months).^1,5 Further studies are needed to understand the clinical progression of SEDC, and more experience is necessary with close follow-up of this subset of patients. Follow-up is determined at the present time from anecdotal experience and patient history.

Along with the rarity of SEDC in our patient, the simultaneous occurrence of 3 primary malignancies also is unusual. Patients with CLL have progressive defects of cell- and humoral-mediated immunity, causing immunosuppression. In a retrospective study, Tsimberidou et al⁹ reviewed the records of 2028 untreated CLL patients and determined that 27% had another primary malignancy, including skin (30%) and lung cancers (6%), which were two of the malignancies seen in our patient. The investigators concluded that patients with CLL have more than twice the risk of developing a second primary malignancy and an increased frequency of certain cancer types.⁹ Furthermore, treatment regimens for CLL have been considered to increase cell- and humoral-mediated immune defects at specific cancer sites,¹⁰ although the exact mechanism of this action is unknown. Development of a second primary malignancy (or even a third) in patients with SEDC is increasingly being reported in CLL patients.^9,10

A high index of suspicion with SEDC in the differential diagnosis should be maintained in elderly men with slow-growing, solitary, nodular lesions of the scalp, nose, arms, legs, or trunk.

The Diagnosis: Nonuremic Calciphylaxis

Histopathologic findings revealed ischemic necrosis and a subepidermal blister (Figure 1) with arteriosclerotic changes and fat necrosis. Foci of calcification were noted within the fat lobules. Arterioles within the deeper dermis and subcutis showed thickened hyalinized walls, narrowed lumina, and medial calcification (Figure 2). Multiple sections did not reveal any granulomatous inflammation. Periodic acid-Schiff and Gram stains were negative for fungal and bacterial elements, respectively. No dense neutrophilic infiltrate was seen. Multifocal calcific deposits within fat lobules and vessel walls (endothelium highlighted by the CD31 stain) suggested calciphylaxis.

Laboratory test results revealed a normal white blood cell count, international normalized ratio level of 4 (on warfarin), and an elevated sedimentation rate at 72 mm/h (reference range, 0-20 mm/h). Serum creatinine was 1.1 mg/dL (reference range, 0.6-1.2 mg/dL) and the calcium-phosphorous product was 40.8 mg²/dL (reference range, <55 mg²/dL). Hemoglobin A_1C (glycated hemoglobin) was 8.2% (reference range, 4%-7%). Wound cultures grew Proteus mirabilis sensitive to cefazolin. Acid-fast bacilli and fungal cultures were negative. Computed tomography of the left lower leg without contrast showed no evidence of osteomyelitis. Of note, the popliteal arteries and distal vessels showed moderate vascular calcification.

Histopathology findings as well as a clinical picture of painful ulceration on the distal extremities and uncontrolled diabetes with normal renal function favored a diagnosis of nonuremic calciphylaxis (NUC). The patient was treated with intravenous infusions of sodium thiosulfate 25 mg 3 times weekly and oral cefazolin for superadded bacterial infection. Local wound care included collagenase dressings with light compression. Warfarin was discontinued, as it can worsen calciphylaxis. Complete reepithelialization of the ulcer along with substantial reduction in pain was noted within 4 weeks.

Ulceration of the lower legs is a relatively common condition in the Western world, the prevalence of which increases up to 5% in patients older than 65 years.¹ Of the myriad of causes that lead to ulceration of the distal aspect of the leg, NUC is a rare but known phenomenon. The pathogenesis of NUC is complicated based on theories of derangement of receptor activator of nuclear factor κβ, receptor activator of nuclear factor κβ ligand, and osteoprotegerin, leading to calcium deposits in the media of the arteries.² This deposition precipitates vascular occlusion coupled with ischemic necrosis of the subcutaneous tissue and skin.³ Some of the more common causes of NUC are primary hyperparathyroidism, malignancy, and rheumatoid arthritis. Type 2 diabetes mellitus is a less common cause but often is found in association with NUC, as noted by Nigwekar et al.² According to their study, the laboratory parameters commonly found in NUC included a calcium-phosphorous product greater than 50 mg²/dL and serum creatinine of 1.2 mg/dL or less.²

Our patient displayed these laboratory findings. However, distinguishing NUC from other atypical lower extremity ulcers such as Martorell hypertensive ischemic ulcer, pyoderma gangrenosum, and warfarin necrosis can pose a challenge to the dermatologist. Martorell hypertensive ischemic ulcer is excruciatingly painful and occurs more frequently near the Achilles tendon, responding well to surgical debridement. Histopathologically, medial calcinosis and arteriosclerosis are seen.⁴

Pyoderma gangrenosum is a neutrophilic dermatosis wherein the classical ulcerative variant is painful. It occurs mostly on the pretibial area and worsens after debridement.⁵ Clinically and histopathologically, it is a diagnosis of exclusion in which a dense neutrophilic to mixed lymphocytic infiltrate is seen with necrosis of dermal vessels.⁶ 

Warfarin necrosis is extremely rare, affecting 0.01% to 0.1% of patients on warfarin-derived anticoagulant therapy.⁷ Necrosis occurs mostly on fat-bearing areas such as the breasts, abdomen, and thighs 3 to 5 days after initiating treatment. Histologically, fibrin deposits occlude dermal vessels without perivascular inflammation.⁸

Necrobiosis lipoidica is a rare cutaneous entity seen in 0.3% of diabetic patients.⁹ The exact pathogenesis is unknown; however, microangiopathy in collaboration with cross-linking of abnormal collagen fibers play a role. These lesions appear as erythematous plaques with a slightly depressed to atrophic center, ultimately taking on a waxy porcelain appearance. Although most of these lesions either resolve or become chronically persistent, approximately 15% undergo ulceration, which can be painful. Histologically, with hematoxylin and eosin staining, areas of necrobiosis are seen surrounded by an inflammatory infiltrate comprised mainly of histiocytes along with lymphocytes and plasma cells.⁹

Nonuremic calciphylaxis can mimic the aforementioned conditions to a greater extent in female patients with obesity, diabetes mellitus, and hypertension. However, microscopic calcium deposition in the media of dermal arterioles, extravascular calcification within fat lobules, and cutaneous necrosis, along with remarkable response to intravenous sodium thiosulfate, confirmed a diagnosis of NUC in our patient. Sodium thiosulfate scavenges reactive oxygen species and promotes nitric oxygen generation, thereby reducing endothelial damage.¹⁰ Although there are no randomized controlled trials to support its use, sodium thiosulfate has been successfully used to treat established cases of NUC.¹¹

The Diagnosis: Nonuremic Calciphylaxis

Histopathologic findings revealed ischemic necrosis and a subepidermal blister (Figure 1) with arteriosclerotic changes and fat necrosis. Foci of calcification were noted within the fat lobules. Arterioles within the deeper dermis and subcutis showed thickened hyalinized walls, narrowed lumina, and medial calcification (Figure 2). Multiple sections did not reveal any granulomatous inflammation. Periodic acid-Schiff and Gram stains were negative for fungal and bacterial elements, respectively. No dense neutrophilic infiltrate was seen. Multifocal calcific deposits within fat lobules and vessel walls (endothelium highlighted by the CD31 stain) suggested calciphylaxis.

Laboratory test results revealed a normal white blood cell count, international normalized ratio level of 4 (on warfarin), and an elevated sedimentation rate at 72 mm/h (reference range, 0-20 mm/h). Serum creatinine was 1.1 mg/dL (reference range, 0.6-1.2 mg/dL) and the calcium-phosphorous product was 40.8 mg²/dL (reference range, <55 mg²/dL). Hemoglobin A_1C (glycated hemoglobin) was 8.2% (reference range, 4%-7%). Wound cultures grew Proteus mirabilis sensitive to cefazolin. Acid-fast bacilli and fungal cultures were negative. Computed tomography of the left lower leg without contrast showed no evidence of osteomyelitis. Of note, the popliteal arteries and distal vessels showed moderate vascular calcification.

Histopathology findings as well as a clinical picture of painful ulceration on the distal extremities and uncontrolled diabetes with normal renal function favored a diagnosis of nonuremic calciphylaxis (NUC). The patient was treated with intravenous infusions of sodium thiosulfate 25 mg 3 times weekly and oral cefazolin for superadded bacterial infection. Local wound care included collagenase dressings with light compression. Warfarin was discontinued, as it can worsen calciphylaxis. Complete reepithelialization of the ulcer along with substantial reduction in pain was noted within 4 weeks.

Ulceration of the lower legs is a relatively common condition in the Western world, the prevalence of which increases up to 5% in patients older than 65 years.¹ Of the myriad of causes that lead to ulceration of the distal aspect of the leg, NUC is a rare but known phenomenon. The pathogenesis of NUC is complicated based on theories of derangement of receptor activator of nuclear factor κβ, receptor activator of nuclear factor κβ ligand, and osteoprotegerin, leading to calcium deposits in the media of the arteries.² This deposition precipitates vascular occlusion coupled with ischemic necrosis of the subcutaneous tissue and skin.³ Some of the more common causes of NUC are primary hyperparathyroidism, malignancy, and rheumatoid arthritis. Type 2 diabetes mellitus is a less common cause but often is found in association with NUC, as noted by Nigwekar et al.² According to their study, the laboratory parameters commonly found in NUC included a calcium-phosphorous product greater than 50 mg²/dL and serum creatinine of 1.2 mg/dL or less.²

Our patient displayed these laboratory findings. However, distinguishing NUC from other atypical lower extremity ulcers such as Martorell hypertensive ischemic ulcer, pyoderma gangrenosum, and warfarin necrosis can pose a challenge to the dermatologist. Martorell hypertensive ischemic ulcer is excruciatingly painful and occurs more frequently near the Achilles tendon, responding well to surgical debridement. Histopathologically, medial calcinosis and arteriosclerosis are seen.⁴

Pyoderma gangrenosum is a neutrophilic dermatosis wherein the classical ulcerative variant is painful. It occurs mostly on the pretibial area and worsens after debridement.⁵ Clinically and histopathologically, it is a diagnosis of exclusion in which a dense neutrophilic to mixed lymphocytic infiltrate is seen with necrosis of dermal vessels.⁶ 

Warfarin necrosis is extremely rare, affecting 0.01% to 0.1% of patients on warfarin-derived anticoagulant therapy.⁷ Necrosis occurs mostly on fat-bearing areas such as the breasts, abdomen, and thighs 3 to 5 days after initiating treatment. Histologically, fibrin deposits occlude dermal vessels without perivascular inflammation.⁸

Necrobiosis lipoidica is a rare cutaneous entity seen in 0.3% of diabetic patients.⁹ The exact pathogenesis is unknown; however, microangiopathy in collaboration with cross-linking of abnormal collagen fibers play a role. These lesions appear as erythematous plaques with a slightly depressed to atrophic center, ultimately taking on a waxy porcelain appearance. Although most of these lesions either resolve or become chronically persistent, approximately 15% undergo ulceration, which can be painful. Histologically, with hematoxylin and eosin staining, areas of necrobiosis are seen surrounded by an inflammatory infiltrate comprised mainly of histiocytes along with lymphocytes and plasma cells.⁹

Nonuremic calciphylaxis can mimic the aforementioned conditions to a greater extent in female patients with obesity, diabetes mellitus, and hypertension. However, microscopic calcium deposition in the media of dermal arterioles, extravascular calcification within fat lobules, and cutaneous necrosis, along with remarkable response to intravenous sodium thiosulfate, confirmed a diagnosis of NUC in our patient. Sodium thiosulfate scavenges reactive oxygen species and promotes nitric oxygen generation, thereby reducing endothelial damage.¹⁰ Although there are no randomized controlled trials to support its use, sodium thiosulfate has been successfully used to treat established cases of NUC.¹¹

The Diagnosis: Nonuremic Calciphylaxis

Histopathologic findings revealed ischemic necrosis and a subepidermal blister (Figure 1) with arteriosclerotic changes and fat necrosis. Foci of calcification were noted within the fat lobules. Arterioles within the deeper dermis and subcutis showed thickened hyalinized walls, narrowed lumina, and medial calcification (Figure 2). Multiple sections did not reveal any granulomatous inflammation. Periodic acid-Schiff and Gram stains were negative for fungal and bacterial elements, respectively. No dense neutrophilic infiltrate was seen. Multifocal calcific deposits within fat lobules and vessel walls (endothelium highlighted by the CD31 stain) suggested calciphylaxis.

Laboratory test results revealed a normal white blood cell count, international normalized ratio level of 4 (on warfarin), and an elevated sedimentation rate at 72 mm/h (reference range, 0-20 mm/h). Serum creatinine was 1.1 mg/dL (reference range, 0.6-1.2 mg/dL) and the calcium-phosphorous product was 40.8 mg²/dL (reference range, <55 mg²/dL). Hemoglobin A_1C (glycated hemoglobin) was 8.2% (reference range, 4%-7%). Wound cultures grew Proteus mirabilis sensitive to cefazolin. Acid-fast bacilli and fungal cultures were negative. Computed tomography of the left lower leg without contrast showed no evidence of osteomyelitis. Of note, the popliteal arteries and distal vessels showed moderate vascular calcification.

Histopathology findings as well as a clinical picture of painful ulceration on the distal extremities and uncontrolled diabetes with normal renal function favored a diagnosis of nonuremic calciphylaxis (NUC). The patient was treated with intravenous infusions of sodium thiosulfate 25 mg 3 times weekly and oral cefazolin for superadded bacterial infection. Local wound care included collagenase dressings with light compression. Warfarin was discontinued, as it can worsen calciphylaxis. Complete reepithelialization of the ulcer along with substantial reduction in pain was noted within 4 weeks.

Ulceration of the lower legs is a relatively common condition in the Western world, the prevalence of which increases up to 5% in patients older than 65 years.¹ Of the myriad of causes that lead to ulceration of the distal aspect of the leg, NUC is a rare but known phenomenon. The pathogenesis of NUC is complicated based on theories of derangement of receptor activator of nuclear factor κβ, receptor activator of nuclear factor κβ ligand, and osteoprotegerin, leading to calcium deposits in the media of the arteries.² This deposition precipitates vascular occlusion coupled with ischemic necrosis of the subcutaneous tissue and skin.³ Some of the more common causes of NUC are primary hyperparathyroidism, malignancy, and rheumatoid arthritis. Type 2 diabetes mellitus is a less common cause but often is found in association with NUC, as noted by Nigwekar et al.² According to their study, the laboratory parameters commonly found in NUC included a calcium-phosphorous product greater than 50 mg²/dL and serum creatinine of 1.2 mg/dL or less.²

Our patient displayed these laboratory findings. However, distinguishing NUC from other atypical lower extremity ulcers such as Martorell hypertensive ischemic ulcer, pyoderma gangrenosum, and warfarin necrosis can pose a challenge to the dermatologist. Martorell hypertensive ischemic ulcer is excruciatingly painful and occurs more frequently near the Achilles tendon, responding well to surgical debridement. Histopathologically, medial calcinosis and arteriosclerosis are seen.⁴

Pyoderma gangrenosum is a neutrophilic dermatosis wherein the classical ulcerative variant is painful. It occurs mostly on the pretibial area and worsens after debridement.⁵ Clinically and histopathologically, it is a diagnosis of exclusion in which a dense neutrophilic to mixed lymphocytic infiltrate is seen with necrosis of dermal vessels.⁶ 

Warfarin necrosis is extremely rare, affecting 0.01% to 0.1% of patients on warfarin-derived anticoagulant therapy.⁷ Necrosis occurs mostly on fat-bearing areas such as the breasts, abdomen, and thighs 3 to 5 days after initiating treatment. Histologically, fibrin deposits occlude dermal vessels without perivascular inflammation.⁸

Necrobiosis lipoidica is a rare cutaneous entity seen in 0.3% of diabetic patients.⁹ The exact pathogenesis is unknown; however, microangiopathy in collaboration with cross-linking of abnormal collagen fibers play a role. These lesions appear as erythematous plaques with a slightly depressed to atrophic center, ultimately taking on a waxy porcelain appearance. Although most of these lesions either resolve or become chronically persistent, approximately 15% undergo ulceration, which can be painful. Histologically, with hematoxylin and eosin staining, areas of necrobiosis are seen surrounded by an inflammatory infiltrate comprised mainly of histiocytes along with lymphocytes and plasma cells.⁹

Nonuremic calciphylaxis can mimic the aforementioned conditions to a greater extent in female patients with obesity, diabetes mellitus, and hypertension. However, microscopic calcium deposition in the media of dermal arterioles, extravascular calcification within fat lobules, and cutaneous necrosis, along with remarkable response to intravenous sodium thiosulfate, confirmed a diagnosis of NUC in our patient. Sodium thiosulfate scavenges reactive oxygen species and promotes nitric oxygen generation, thereby reducing endothelial damage.¹⁰ Although there are no randomized controlled trials to support its use, sodium thiosulfate has been successfully used to treat established cases of NUC.¹¹