Extramammary Paget’s Disease

Abstract

Extramammary Paget’s disease, originally described by Crocker in 1889, is a rare apocrine adenocarcinoma that appears in the epidermis and from there may extend into the epithelial structures of adnexa and dermis. The pathogenesis of EMPD is still controversial. There are two different forms of EMPD with distinct pathogenetic mechanisms. The “primary” form represents the majority of the cases and is considered the only true EMPD. It originates in the skin, presumably from an undifferentiated pluripotent cell of the epidermis and/or its adnexa. It has also been suggested that Toker cells, intraepidermal cells with abundant clear to pale cytoplasm present in the nipple, along the milk line and in the vulva, are the benign precursors of Paget cells. The “secondary” EMPD form constitutes about 25 % of cases and is considered to represent an epidermotropic spread from an underlying adnexal or visceral adenocarcinoma (genitourinary, gastrointestinal, or another distant site).