Fibroadenoma and phyllodes tumors of anogenital mammary-like glands: a series of 13 neoplasms in 12 cases, including mammary-type juvenile fibroadenoma, fibroadenoma with lactation changes, and neurofibromatosis-associated pseudoangiomatous stromal hyperplasia with multinucleated giant cells.

The authors present a series of 13 fibroepithelial neoplasms involving anogenital mammary-like glands, all occurring in 12 female patients, whose age at diagnosis ranged from 30 to 51 years (mean, 38 y; median, 42 y). All women presented with a solitary asymptomatic nodule in the vulva (n=8), perineum (n=2), or near the anus (n=2) ranging in size from 1.5 to 4.5 cm. Microscopically, 8 lesions were classified as fibroadenoma, and 5, including 1 recurrent tumor, as phyllodes tumor, of which 1 was benign and 4 low-grade malignant. In addition to conventional findings, we describe several hitherto unreported features including juvenile fibroadenoma-like proliferation, fibroadenoma with lactation change, and pseudoangiomatous stromal hyperplasia with multinucleated stromal giant cells in a patient with neurofibromatosis, type 1 all constituting potential diagnostic pitfalls, which are best averted by using the same approach to diagnosis as for their analogous mammary counterparts.