Pleomorphic adenoma of the breast: case report and review of the literature.

A tumor of the right breast was noticed in a 70 year old female. The tumor was round, 1 x 1 cm, and was encapsulated with thin fibrous tissue. The boundary was clear. The cut surface showed a mosaic pattern of brown and white dots and the texture was gritty. Histologically, glandular structures, trabecular or solid epithelial cell nests, myxoid, cartilaginous and osteoid areas, and one ossifying focus were found. Round, polyhedral or fusiform myoepithelial cells proliferated around the glandular structures and were dispersing into the myxoid and cartilaginous tissue. Myoepithelial proliferation was especially marked around the small glandular structure. Immunohistochemically, S-100 protein was strongly positive for the myoepithelial cells around the glandular structures and in the cartilaginous tissue. Until now, 54 cases of pleomorphic adenoma of the breast have been reported. In those cases, the subareolar region was a common site for the tumor, and pleomorphic adenoma was thought to arise from large ducts in this region. No Oriental patients have been reported in the literature.