A case of primary malignant fibrous histiocytoma (MFH) of the breast

We report a rare case of primary mammary malignant fibrous histiocytoma (MFH). A 57-year-old woman was found in aspiration cytology to have a cluster of markedly pleomorphic tumor cells, consisting of atypical fibroblastic and histiocytic cells, in a right breast mass, together with giant cells with bizarre nuclei and inflammatory cells. Histopathologically, tumor cells showed storiform pattern and were immunohistochemically positive for vimentin, KP-1, and α1-antitrypsin, yielding an MFH diagnosis. Cytological findings were thus found useful in diagnosing primary mammary MFH.