Vulvar Lactating Adenoma: A Rare Representation of Mammary-Like Anogenital Glands

Mammary-like anogenital glands are considered a normal constituent of the anogenital area. These glands can have epithelial components with eccrine or apocrine features. They often undergo transformation into mammary-like lesions, including lactational changes that occur during pregnancy and the breastfeeding period. When they form mass lesions they are referred to as lactating adenomas. Their appearance can clinically be mistaken for other more common benign and malignant entities in the vulva. We describe a vulvar lesion in a 26-year-old woman. The lesion was excised and determined by histologic examination to be a benign lactating adenoma. Subsequent immunohistochemistry was performed. The epithelial cells were positive for GATA3 and estrogen receptor while negative for PAX8, supporting mammary-like differentiation. The myoepithelial markers p63 and calponin were positive at the periphery of the ducts, supporting the benign nature of this lesion.