This tumor occurs exclusively in females and is thought to represent an external genital equivalent to breast intraduct papilloma. It is probably derived from the ano-genital mammary-like glands

Clinical features

•Almost all cases have arisen in females, generally white & young-middle-aged

•Occasionally symptomatic- pruritus, pain etc

•Male cases represent misdiagnosed cystic apocrine hidradenoma

•Small, asymptomatic solid/cystic papule or nodule (0.3-2 cm) on vulva or in a perineal/perianal location

•Any vulval site may be affected

Histological features

•Circumscribed intradermal/lamina propria nodule

•Cystic or solid

•Papillae lined by myoepithelial cells with overlying epithelial cells with eosinophilic cytoplasm showing decapitation secretion

•+/- Oxyphil metaplasia

•Cribriform pattern sometimes evident

•Solid pattern

•Exceptionally, sebaceous differentiation

•DPAS +ve granules

•Mitoses can be absent or even brisk

•No pleomorphism or abnormal mitoses

•No necrosis, lymphovascular invasion or perineural infiltration

•CK7, EMA, CEA, ER, PR, GCDFP-15, HMFP-1 +ve

•Myoepithelial cells p63, S100, SMA +ve

Differential diagnosis

Malignant change is vanishingly rare. Features include an infiltrating margin, nuclear pleomorphism, abnormal mitoses & necrosis