Alveolar variant of infiltrating lobular carcinoma of the breast with stromal osteoclast-like giant cells.

An alveolar variant of infiltrating lobular carcinoma of the breast in which a prominent feature was the presence of numerous osteoclast-like giant cells in a richly vascularized stroma is described. A similar stromal reaction has previously been reported in 46 breast carcinomas of various histologic types, but only once in a pure infiltrating lobular carcinoma. The fine needle aspiration cytological and histological appearances and the immunohistochemical and ultrastructural features of this tumor are reported. Our study confirms the histiocytic nature of the multinucleated giant cells and their similarity to normal osteoclasts.