Carcinoma in a fibroadenoma.

A carcinoma arising within a fibroadenoma is an unusual occurrence, with only a little over 100 reported cases. The purpose of this report is to increase the awareness of this entity and to discourage the practice of rendering a diagnosis on gross examination of the tumor. We are reporting a case with two distinct primary tumors within the same breast, one of which was arising within the fibroadenoma.