Abstract

Squamoid eccrine ductal carcinoma (SEDC) is a rare primary cutaneous adnexal malignancy that has the potential for an aggressive clinical course, particularly a high rate of local recurrence, lymphovascular invasion, perineural invasion, and metastases. First described by Wong et al in 1997, SEDC typically has a biphasic histologic appearance comprising of a superficial portion similar to squamous cell carcinoma (SCC) and a deeper portion with eccrine ductal differentiation. Due to superficial sampling, SEDC is sometimes misdiagnosed as SCC during the initial biopsy. The diagnosis is later established with complete excision. Confirmation of the diagnosis can be made by immunohistochemical positivity for carcinoembryonic antigen (CEA), epithelial membrane antigen (EMA), cytokeratin (CK) 5/6, and p63. Herein, we describe a case of SEDC in the left malar area of a 73 year old male which had initial predominant squamous differentiation in the biopsy while the excision specimen had the classical bi-phasic pattern with superficial squamoid differentiation and deeper levels showing ductal morphology with perineural infiltration. The aim of this report is to emphasize the importance of recoginition of this entity as there could be extensive perineural invasion with the possibility of positive margins on frozen section.

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