Mammary diffuse fibroadenomatoid hyperplasia in water buffalo (Bubalus bubalis): three cases

The current report describes 3 rare cases of mammary diffuse fibroadenomatoid hyperplasia in water buffalo (Bubalus bubalis). All of the animals were between 10 and 12 months of age. Grossly, the lesions consisted of severe diffuse swelling with homogeneous large masses in the udder. Surgical removal of the masses was curative. Microscopically, there was severe hyperplasia of the mammary epithelium and numerous well-differentiated and mildly pleomorphic acini and their associated ducts. Moderate proliferation of the fibrous connective tissue and the myoepithelial cells near the proliferating acini was also evident. The hyperplastic epithelial cells exhibited positive immunostaining for cytokeratin, estrogen receptors, and progesterone receptors. In addition, the myoepithelial cells displayed moderate positivity for alpha smooth muscle actin. Based on the clinical, morphologic, and immunohistochemical findings, a diagnosis of mammary diffuse fibroadenomatoid hyperplasia with probable hormonal influence was made.