Apocrine Carcinoma of the Breast: Clinicopathological Analysis and Histological Subclassification of 12 Cases

BACKGROUND: Apocrine carcinoma is rare and most of its clinicopathological features are still unknown. The purpose of this study was to identify the clinicopathological characteristics of apocrine carcinoma. METHODS: We clinicopathologically analyzed apocrine breast carcinomas resected from 12 Japanese women and subclassified them histopathologically. RESULTS: The average age of the patients at diagnosis was 60.1 years (range: 38-78). Tumor diameters ranged from 0.5 to 4.5 cm (median 2.4). Mammography revealed tumor shadows without microcalcifications in all patients. Two (17%) of the12 patients were lymph node metastasis-positive, and lymphatic permeation by tumor cells was observed in 3 (25%). Apocrine carcinoma in this study could be classified into three subtypes according to predominant histopathological growth pattern: type I, intraductal spreading type (4 patients); type II, adenosis-associated type (3 patients); and type III, infiltrating type (5 patients). Types I and II showed no lymph node metastasis and had an excellent prognosis, whereas theinfiltrating type was associated with lymph node metastasis and death from cancer. Estrogen receptors and progesterone receptors were positive in 17% (1/6) and 60% (3/5), respectively, of the tumors tested. CONCLUSION: In the present study, apocrine carcinoma of the breast was characterized by higher patient age and tumor shadows without microcalcifications on mammography. However, the tumors were heterogenous with regard to pattern of local spread.