HISTOLOGIC SPECTRUM OF CARCINOMAS WITH ECCRINE DUCTAL DIFFERENTIATION(SWEAT-GLAND DUCTAL CARCINOMAS)

Seven cases of sweat-gland carcinomas showing eccrine ductal different iation (ductal carcinomas) are presented. The tumors had a variable hi stological appearance, but were basically characterized by the followi ng histological elements: (a) tubular structures, sometimes cystic or having a ''tadpole'' appearance; (b) solid islands of squamous, basalo id, or clear cells; (c) periodic acid-Schiff-positive endoluminal and/ or intracellular material; and (d) infiltrating growth. Immunocytochem ically, tumor cells were positive for keratin and negative for actin. Endoluminal material contained carcinoembryonic antigen in five of sev en cases. Although it is not yet clear whether carcinomas exhibiting e ccrine ductal differentiation may represent a specific histotype or a group encompassing several distinct clincopathological entities, the h istological analysis of the cases suggested that the wide spectrum of their histological appearances may be due to variable grades of differ entiation.