Male breast carcinoma: a clinicopathological and immunohistochemical characterization study.

Male breast carcinoma is a relatively rare disease. This study retrospectively investigated the clinicopathological features of 73 cases of male breast carcinoma in Chinese population, and classified the molecular subtype based on surrogate immunohistochemical definitions. The expression of GCDFP15, MGB, AR and FOXP1 were evaluated. Invasive carcinoma of no special type was the most common histological type in the study group (71.2%, 52/73). The luminal A and B subtypes were the major types of male breast carcinoma (60.9%, 34.8% respectively). AR and FOXP1 are expressed in 84.2% (48/57) and 71.9% (41/57) of the studied cases. Carcinoma of the luminal A subtype expressed GCDFP15 (73.5%, 25/34) and MGB (58.8%, 20/34) more frequently than cases of the luminal B subtypes (34.8%, 8/23 and 43.5%, 10/23, respectively; P = 0.004, P = 0.255, respectively). In conclusion, invasive carcinoma of no special type was the most common histological type in male breast carcinoma among Chinese population. Our study revealed that the luminal A and B subtypes were the major types of male breast carcinoma. AR and FOXP1 are highly expressed in male breast cancer. The luminal A subtype tends to express GCDFP15 and MGB more frequently than the luminal B subtype.