Syringocystadenoma papilliferum associated with apocrine poroma.

A 65-year-old Japanese man presented with a gradually enlarging mass on the right side of the abdomen, which he had first noticed about 4 years previously. He was otherwise asymptomatic. Histopathological examination of the mass revealed an aggregation of neoplastic cells (tumor cell nests) with cellular proliferation extending from the epidermis to the dermis. The tumor consisted of two histologically distinct parts. One part was composed of uniformly small cells with a cuboidal appearance. Some ductal structures were visualized, and some of the cells lining the ductal lumina contained decapitation secretions. These histological changes were consistent with the diagnosis of apocrine poroma. The remaining part of the tumor was composed of cystic invaginations with numerous projections oriented toward the lumen. There were two rows of cells in the projections; the cells on the luminal side were columnar, and those at the apical aspect were small cuboidal cells. These histological changes were characteristic of syringocystadenoma papilliferum (SCAP). Based on these findings, a diagnosis of SCAP associated with apocrine poroma was made. To the best of our knowledge, there have been no previous reports of such a case in the published work.