Unusual hyperplasia of anogenital mammary-like glands

Anogenital mammary-like glands, although known to exist (as ectopic breast tissue) as early as 1872, have only recently been thoroughly studied and suggested to be the possible origin for various neoplastic (benign and malignant) and reactive conditions that show a striking homology with lesions in the breast. Reported herein is an unusual benign lesion involving anogenital mammary-like glands in the perineal area of a 41-year-old woman. The lesion is unique in that it does not fully fit into any of the previously recognized conditions affecting anogenital mammary-like glands nor has it an apparent well-defined mammary counterpart. Microscopically, at first glance the lesion appeared as a cluster of extended anogenital mammary-like glands of variable complexity and a lobular architecture, which probably resulted from a compact proliferation of closely situated ducts with small, round lumens (when cut transversally). When cut longitudinally, some of these tiny ducts appeared to bud from larger ductal structures, resembling so-called satellitosis in the breast and this gave a fibroadenomatous appearance to the areas. In addition, there were adenosis-like areas. This lesion extends the spectrum of changes seen in anogenital mammary-like glands.