During the past century an interesting literature pertaining to a group of rare tumors of the breast has developed. Collectively they are characterized by the presence of bone, cartilage, fibrous tissue and pleomorphic cells, and, depending on whether these elements are found alone or in combination, the tumors have been reported as chondroma, osteochondroma, chondrosarcoma, osteochondrosarcoma, osteosarcoma, osteoid sarcoma, giant cell sarcoma, myeloid sarcoma, mixed tumor, osteoclastoma and teratoma. In 1700 Bonet1 reported bbserving in a female breast a stony hard mass "which could not be cut with a knife." Since at this period microscopic study of tissue had not evolved and also because stony hard tumors were called bony or cartilaginous, it would be inaccurate to refer to this early contribution as the first example of the tumors under discussion. The same critical attitude must be maintained toward the bony and cartilaginous tumors reported by Morgagni,2 Reil,