Ber-EP4 is a useful marker for follicular germinative cell differentiation of cutaneous epithelial neoplasms.

Ber-EP4 is a monoclonal antibody that recognizes 34-kDa and 39-kDa non-covalently linked glycopolypeptides expressed by most human epithelial cells and carcinomas. In this study, we performed immunohistochemical staining of 31 cases of basal cell carcinoma (BCC); 20 cases of trichoblastoma (TB), including ten cases of nodular type, eight cases of cribriform type (trichoepithelioma) and two cases of columnar type (desmoplastic trichoepithelioma); 16 cases of actinic keratosis (AK); and 10 cases each of Bowen's disease, poroma and seborrheic keratosis. Six cases of BCC and AK were co-lesions of both neoplasms. In normal skin tissue, Ber-EP4 reacted positively with the secretory portion of eccrine glands and follicular germinative cells at the lower end of catagen hairs. Neoplastic cells in 97% of cases with BCC reacted positively with Ber-EP4 in at least 5% of neoplastic cells. Those in 90% with nodular type TB and 50% with trichoepithelioma also reacted positively in at least 5% of neoplastic cells. No cases of poroma, seborrheic keratosis, AK or Bowen's disease were immunohistochemically positive for Ber-EP4 in neoplastic cells. In all six cases with co-lesions of BCC and AK, neoplastic cells of BCC reacted positively with Ber-EP4 and those of AK were negative. Immunohistochemical examination using the Ber-EP4 antibody is a useful tool for diagnosing neoplasms with follicular germinative differentiation, such as TB, TE or BCC, and for differentiating those from squamous cell carcinoma in situ, poroma or seborrheic keratosis.