Eccrine syringofibroadenoma. Report of a case and immunohistochemical study of keratin expression.

We report a 49-year-old woman with an eccrine syringofibroadenoma. An asymptomatic nodule appeared on the right heel, and subsequently enlarged gradually. Histological examination revealed anastomosing strands of pale epithelial cells, with occasional duct formation and mucinous fibrovascular stroma. There were two types of strands: thick and thin. Immunohistochemical study, using a panel of monoclonal antikeratin antibodies, revealed that the immunoreactivity differed between the two types of strands. The thick strands showed a staining pattern similar to the uppermost portion of the intradermal duct, and the thin strands showed a pattern similar to the other portion of the duct. This observation suggests that the thick and thin strands differentiate towards the uppermost portion and the remainder of the duct, respectively.