Extramammary Paget's disease of the perianal and perineal regions. Evidence of apocrine derivation.

A case of perianal and perineal extramammary Paget's disease in a male is reported. The presence of gross cystic disease fluid protein--a new marker of apocrine epithelia--in Paget's cells provides additional insight into the histopathogenesis of this condition. This marker may be a valuable diagnostic adjunct in evaluating intra-epithelial malignancies at a variety of anatomic sites.