Eccrine Mucinous Metaplasia Associated with An Apocrine Cystadenoma

Abstract

Mucinous metaplasia occurs uncommonly in cutaneous pathology, usually at specialized anatomic locations (genitalia, palms, soles) and within restricted pathologic contexts (inflammation, trauma). Here we report a unique case of eccrine mucinous metaplasia associated with an apocrine cystadenoma. A 13‐year‐old girl had an asymptomatic, 4‐mm nodule on the chest. Histopathology demonstrated a typical apocrine cystadenoma in the upper and middle dermis. Adjacent to this neoplasm was a cluster of coiled eccrine secretory ducts, of which the inner layer was almost entirely replaced by benign‐appearing cells containing abundant, non‐sulfated acid mucopolysaccharides. At eight months’ follow‐up, there was no recurrence. Our case demonstrates that, very uncommonly, mucinous metaplasia may be associated with a pathogenetically separate, adjacent neoplasm, in this instance an apocrine cystadenoma.