Fibroadenoma of the vulva with pseudoangiomatous stromal hyperplasia: A common neoplasm in uncommon site

Abstract

Mammary‐type tissue in the vulva was first described in 1872 but has been rarely reported in the literature. This tissue was previously considered as ectopic breast tissue that occurs as a result of incomplete regression of the milk line. Similar to native breast tissue, ectopic mammary tissue is hormone‐sensitive and can develop benign changes, such as fibroadenoma, as well as malignant changes. A more recent theory suggests that these benign and malignant mammary‐type entities arise from mammary‐like anogenital glands, which constitute normal vulvar components. We report a case of a 41‐year‐old woman who presented with a chronic asymptomatic cyst on the left vulva that eventually became uncomfortable, especially on standing. The cyst was located on the labium minus, measuring 1.0 × 0.5 cm, with no identified erythema or other skin abnormalities. Excision of the lesion and subsequent microscopic examination showed a circumscribed mass with a nodular overgrowth of epithelial and stromal components, resembling a mammary fibroadenoma with pseudoangiomatous stromal hyperplasia. We bring to attention this rare diagnosis and the importance of considering it in the presence of a vulvar lesion. The malignant and recurrence potential of mammary‐type tissue necessitates excision with clear margins and close monitoring of these patients.