Poroma with sebaceous differentiation: report of three cases.

We herein report three cases of poroma, which showed sebaceous differentiation. The patients were two men and one woman, and the involved sites were the thigh, head and back. In all three cases, histopathological examination revealed anastomosing nests consisting of poroid cells proliferating into the dermis. Tubular structures lined by eosinophilic cuticular cells were scattered in the tumour nests. Furthermore, aggregations of mature sebocytes with vacuolated cytoplasm were also observed forming clusters, or intermingled with the poroma cells. Focal calcification was found within the nests in two cases. Sebaceous component were recognized in the presented three cases among the 62 cases (4.8%) examined in our department within the past 10 years. We also include a review of the 31 reported cases of poroma with sebaceous differentiation. None of them occurred in acral regions, where typical eccrine poromas predominate. The majority of cases were benign. This review indicates that some poromas may show sebaceous differentiation and be of apocrine lineage.