Squamoid Eccrine Ductal Carcinoma: A Case Report and Review of the Literature

Abstract

Eccrine ductal carcinoma is a rare adnexal tumor. Squamoid eccrine ductal carcinoma (SEDC) represents an exceptionally rare variant with only 6 cases reported to date. This neoplasm is deeply infiltrative and may provide a diagnostic challenge in superficial shave biopsies of skin. We present a case of SEDC in an immunocompromised patient, who, after an initial shave biopsy for diagnostic purposes, underwent a complete excision of his tumor by Mohs micrographic surgery. A combined histologic and immunohistochemical approach is necessary to identify and confirm the unique characteristics of SEDC. Because this cancer is very rare and little is known about its biologic behavior, optimal diagnostic and treatment guidelines need to be developed.

Squamoid eccrine ductal carcinoma of the scalp

“…The superficially located squamous aggregates, focal ductal differentiation and lack of histological stratification and keratinous cystic structures help to differentiate SEDC from microcystic adnexal carcinoma with squamous features, although these differences are not always obvious. 1 The superficial squamatisation and ductal differentiation that are positive for epithelial membrane antigen seen in SEDC are often not as prominent in adenosquamous carcinoma (ASC). 1 Focal luminal positivity with CK7 may also be a more notable feature of ASC than SEDC.…”

“…1 The superficial squamatisation and ductal differentiation that are positive for epithelial membrane antigen seen in SEDC are often not as prominent in adenosquamous carcinoma (ASC). 1 Focal luminal positivity with CK7 may also be a more notable feature of ASC than SEDC. 1,[12][13][14][15] The rarity of MEC makes it difficult to analyse whether histological differences, such as squamoid differentiation, translate to specific clinical behaviour.…”

“…[1][2][3][4][5][6][7] The first 3 cases were reported in 1997, and focal ductal differentiation, intracytoplasmic lumina formation, focal continuity with eccrine ductal epithelium, and atypical squamoid components are features that differentiate SEDC from squamous cell carcinoma. 8 A further case is reported.…”

Who should have Mohs micrographic surgery?

“…Extramamary Paget's disease has a contiguous growth pattern [38] and wide subclinical extensions with better results reported when treated by MMS [39 ]. Squamous eccrine duct carcinoma [40], adenosquamous carcinoma of the skin [41], adenoid cystic carcinoma [42], hidradenocarcinoma [43] and myoepithelioma [44] have all been successfully managed with MMS. Very large head and neck nonmelanoma skin cancer can use MMS to gain peripheral margin control as part of a multidisciplinary approach [45 ] but long-term outcome may be affected by inability to completely extirpate the deeper parts of the tumour even with a multidisciplinary team.…”

PET/CT Imaging of Squamoid Eccrine Ductal Carcinoma

“…[2][3][4] This is only the tenth reported case of SEDC, and the first case of 18 F-FDG PET/CT evaluation of SEDC in literature. [2][3][4][5][6][7][8] FIGURE 2. The patient returned to the dermatology clinic 2 months after amputation/resection and noted an enlarging skin lesion over her left distal triceps for 2 weeks.…”