Phyllodes - like Tumor of the Anogenital Mammary - like Glands – A Rare Entity

Abstract Introduction/Objective Phyllodes tumor (PT), a biphasic fibroepithelial tumor typically found in the breast, is an exceedingly rare finding outside the mammary gland, with only about 160 cases reported to date. We describe a rare case of PT arising from anogenital mammary-like glands (AGMLG). Methods/Case Report A 68-year-old woman presented with a small perianal mass that was incidentally detected during hemorrhoidectomy procedure. It appeared as a pedunculated olive-sized mass on the perianal skin. A papillectomy was performed, and upon sectioning, a solid-cystic lesion measuring 2.0 x 1.4 x 0.9 cm was observed. Microscopic examination revealed a biphasic pattern comprising of glandular epithelium and a stromal component, with a predominance of the latter and together they formed leaf-like slits. These spaces were lined by a bilayered epithelium consisting of secretory (apocrine)-type cells and myoepithelial cells resembling mammary glandular epithelia. Focal clusters of benign glands, morphologically consistent with AGMLGs, were identified at the periphery of the tumor. Immunohistochemically, epithelial components reacted positively for GATA3, mammoglobin, CK7, estrogen receptor and progesterone receptor, while the myoepithelial cells were highlighted by calponin and p63. The AGMLGs in the periphery also stained for GATA3, estrogen receptor and progesterone receptor. The mitotic rate was low (1 to 2 per 50 high-power fields), without atypical mitoses. The lesion was diagnosed as a benign PT. Results (if a Case Study enter NA) NA Conclusion The current case highlights the importance of recognizing PT when it occurs at extra-mammary locations. The entity merits greater attention not only for its malignant potential but also due to the mystery surrounding its origin and the histogenetic link to breast tissue.