Immunohistochemical staining patterns of type VI collagen in the normal, hyperplastic, and neoplastic adult male breast.

Ten cases of primary invasive male breast ductal carcinomas (N.O.S.), one case of male breast fibroadenoma, seven cases of pure florid gynecomastia and four cases of normal mammary glands were examined immunohistochemically for type VI collagen expression and distribution. In normal male breast type VI collagen was absent in the whole fibrous stroma. On the contrary this collagen was markedly expressed in the stroma of invasive carcinoma as well as fibroadenoma and gynecomastia. In all these proliferative diseases, type VI collagen gave a distinct basement membrane-like deposition at the epithelial-stromal junctions while organized a fibrillar network in the interstitium. Our immunohistochemical findings showed that type VI collagens is involved in the stromal response of benign and malignant male breast proliferative diseases.