HISTIOCYTOID BREAST-CARCINOMA - HISTOLOGICAL, IMMUNOHISTOCHEMICAL, ULTRASTRUCTURAL, CYTOLOGICAL AND CLINICOPATHOLOGICAL STUDIES

Histiocytoid breast carcinoma (HBC) is a rare variant of breast carcin oma and often causes a diagnostic dilemma because of its histological similarities to some types of breast cancer and benign lesions. To elu cidate the incidence of HBC and its biological properties, histologica l specimens from 1010 breast cancer patients treated at Yokohama Minam i Kyosai Hospital between 1972 and 1996 were reviewed, Three cases of pure HBC and three cases of combined HBC (two with pleomorphic lobular carcinoma and one with apocrine ductal carcinoma) were found, yieldin g an incidence of 0.3% for each, Two of the three pure HBC cases conta ined foci of in site lobular carcinoma. Targetoid and Indian file inva sive patterns, the features characteristic of lobular carcinoma, were present in all three pure HBC cases and in two of the three combined H BC with pleomorphic lobular carcinoma. These results, together with th ose of previous studies, suggested that the majority of HBC are of lob ular origin, although the apocrine ductal origin is also possible in a small number of HBC, Diastase-resistant periodic acid-Schiff-positive granules and granular immunoreactivities for gross cystic disease flu id protein-15 (GCDFP-15) were characteristic of the histiocytoid tumor cells in both the pure and combined HBC, suggesting the apocrine diff erentiation of tumor cells. All three pure HBC cases were in stage 1 a nd were free of the disease for up to 5 years and 1 month after the lu mpectomy, Thus, the prognosis of HBC appears to be dependent on the st age of the disease and may not always be poor, as indicated by the ori ginal report mentioning a preferential eyelid metastasis.