Potential use of monoclonal antibodies in the diagnostic distinction of gynecomastia from breast carcinoma in men.

Immunohistochemical (IHC) assays using the monoclonal antibodies (MoAbs) B72.3 and B6.2, recognizing two distinct and independently expressed breast tumor-associated antigens (BTAAs), recently have been shown to significantly improve the accuracy of cytodiagnosis of breast nodules by fine-needle aspiration (FNA). To evaluate whether the same method may be useful diagnostically in distinguishing gynecomastia from breast cancer in men, a retrospective avidin-biotin immunoperoxidase assay study was performed on 50 cases of gynecomastia and 30 cases of breast carcinoma in men, using a panel of five MoAbs known to recognize different BTAAs. The results of this study demonstrated that MoAbs B1.1, HMFG2, and MBr1 displayed a strong reactivity with gynecomastia and carcinoma, but MoAbs B72.3 and B6.2 separated benign and malignant lesions in a high percentage of cases. When used in combination, the latter two reagents reacted with 96% of the carcinomas that were analyzed but labeled only 67% of gynecomastia cases. Thus, the conjoint use of these two reagents may enhance the use of FNA biopsy as a valuable tool in the presurgical diagnosis of breast nodules in men.