CEACAM5 and squamous cell carcinoma: EMA is a strong marker for ductal structures.[8] Among the most commonly used CK markers, positive CK15 may help distinguish MAC from invasive BCC and squamous cell carcinoma.[9] Carcinoembryonic antigen is considered to be a selective marker for demonstrating ductal differentiation in MAC, which is beneficial for eccrine and apocrine ducts in MAC.[6] Ber-EP4, a monoclonal antibody, is believed to be useful for distinguishing between MAC (Ber-EP4 negative) and BCC (Ber-EP4 positive).[9]