Squamoid eccrine ductal carcinoma of the ear helix

Abstract

Key Clinical Message Chronic cutaneous ulcer on the ear helix of 80‐year‐old male was diagnosed with squamoid eccrine ductal carcinoma (SEDC). SEDC is characterized by both atypical squamous and ductal differentiation. SEDC frequently appears on sun‐exposed areas. It could show local recurrence despite complete resection. These characteristics demand cautious attention to SEDC.

Squamoid Eccrine Ductal Carcinoma

“…Our review yielded 56 cases of SEDC. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] The mean age of patients with SEDC was 72 years. The number of male and female cases was 52% (29/56) and 48% (27/56), respectively.…”

“…The combination of histologic features with the immunoexpression profile of carcinoembryonic antigen (CEA), epithelial membrane antigen (EMA), cytokeratin (CK) 5/6, and p63 can effectively exclude the other entities in the differential and confirm the diagnosis of SEDC. 1,3,4 While the diagnosis of SEDC relies on the specific histologic features of multiple surface attachments and superficial squamoid changes with deep ductular elements, immunohistochemistry can nonetheless be adjunctive in difficult cases. Positive immunohistochemical staining for CEA and EMA can help to highlight and delineate true glandular elements, whereas CK5/6 highlights the overall contour of the tumor, displaying more clearly the multiple epidermal attachments and the subtle infiltrative nature of the deeper components of invasive cords and ducts.…”

“…Risk factors include male sex, increased age, and chronic immunosuppression. [1][2][3][4] Current reports suggest that SEDC is likely a high-grade subtype of squamous cell carcinoma (SCC) with a high risk for local recurrence (25%) and metastasis (13%). 1,3,5,6 There are as few as 56 cases of SEDC reported in the literature; however, the number of cases may be closer to 100 due to SEDC being classified as either adenosquamous carcinoma of the skin or ductal eccrine carcinoma with squamous differentiation.…”

“…Multiple connections to the overlying epidermis also can be seen, serving as a subtle clue to the diagnosis on broad superficial specimens. [1][2][3] Due to superficial sampling, approximately 50% of reported cases are misdiagnosed as SCC during the initial biopsy. 4 The diagnosis of SEDC often is made during complete excision when deeper tissue is sampled.…”

“…Establishing an accurate diagnosis is important given the more aggressive nature of SEDC compared with SCC and its proclivity for PNI. 1,3,6 The purpose of this review is to increase awareness of this underrecognized entity and describe the histologic findings that help distinguish SEDC from SCC.…”