Extraskeletal osteosarcoma in the axilla associated with breast carcinoma

A case of extraskeletal osteosarcoma arising in the axilla in a 77-year-old woman is described. Because of its association with an ipsilateral breast carcinoma, the axillary mass was at first assumed to be a lymph node with metastatic breast carcinoma. The occurrence of extraskeletal osteosarcoma in the axillary is rare and association with breast carcinoma has never, to our knowledge, been described.