[Extramammary Paget's disease with an underlying mucinous adenocarcinoma of the buttocks].

A 67-year-old woman with extramammary Paget's disease of the buttocks is reported. She manifested an eczematous skin lesion of both sides of the buttock and had an intradermal tumor of the right side. Resected specimens revealed widely spreading Paget's cells (15.5 X 15 cm), an intraepidermal adenocarcinoma (1 X 0.6 cm) in the eczematous epidermis, and an intradermal mucinous adenocarcinoma (3.3 X 2 X 2.5 cm). The intraepidermal adenocarcinoma was located just above the intradermal mucinous adenocarcinoma. From the histological localization of these lesions, and the electron microscopical findings of the Paget's cells and the intraepidermal adenocarcinoma, this case was thought to have started as an intraepidermal adenocarcinoma, which might have originated from the intraepidermal eccrine gland.