Squamoid eccrine ductal carcinoma.

Squamoid eccrine ductal carcinoma (SEDC) is an extremely rare cutaneous tumor of unknown etiology. We report the case of a 77-year-old man with a history of treated chronic lymphocytic leukemia along with numerous basal cell and squamous cell carcinomas who presented for evaluation of a 5-cm, stellate, sclerotic plaque on the left chest of approximately 2 years' duration and a suspicious 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 that extended from the undersurface of the epidermis, favoring a diagnosis of SEDC. It was later determined that the patient had distant metastasis of SEDC. This report of an immunocompromised patient with SEDC is a rare case of distant metastasis of SEDC. A review of the literature on the diagnosis, treatment, and surveillance of SEDC also is provided.