Monoclonal antibody Ber-EP4 reliably discriminates between microcystic adnexal carcinoma and basal cell carcinoma

Background: Sclerosing cutaneous neoplasms often represent a diagnostic challenge. The monoclonal antibody Ber-EP4 recognizes two glycopolypeptides found in most human epithelial cells. It is diagnostically highly reliable in the differentiation between basal cell carcinoma and cutaneous squamous cell carcinoma. In this study, we report its application in the differential diagnosis of microcystic adnexal carcinoma, desmoplastic trichoepithelioma and basal cell carcinoma. Methods: Biopsy samples from 28 sclerosing and infiltrating basal cell carcinomas, 13 microcystic adnexal carcinomas and 16 desmoplastic trichoepitheliomas were examined after immunohistochemical staining with Ber-EP4. Results: Ber-EP4 did not label any of the microcystic adnexal carcinomas, whereas all 28 basal cell carcinomas were Ber-EP4 positive. Twenty-seven of the 28 showed moderate or strong staining intensity, with the majority being strong. Only one basal cell carcinoma was weakly positive. Twelve of the 16 desmoplastic trichoepitheliomas were immunoreactive with Ber-EP4 and the staining was more variable than those of basal cell carcinomas. Conclusions: Ber-EP4 reliably differentiates microcystic adnexal carcinoma from basal cell carcinoma to the same extent as it distinguishes the latter tumor from squamous cell carcinoma. While it stains the majority of desmoplastic trichoepitheliomas, these tumors still have to be considered in the differential diagnosis with microcystic adnexal carcinoma, when Ber-EP4 is applied. Krahl D, Sellheyer K. Monoclonal antibody Ber-EP4 reliably discriminates between microcystic adnexal carcinoma and basal cell carcinoma.