Primary lymphoma of the breast: ultrastructural study of two cases.

Two cases of primary non-Hodgkin's lymphomas of the breast were studied with light and electron microscopy. By light microscopy, according to Rappaport's classification, one was a poorly differentiated lymphocytic lymphoma, the other a diffuse histiocytic lymphoma. However, the ultrastructural features of the latter were more consistent with transformed lymphocytes. The differential diagnosis with medullary and poorly differentiated carcinomas of the breast is discussed. The first case had rapid dissemination as did most of the cases reported in the literature.