A Comparative Study of CD56 and Smooth Muscle Actin Expression in Basal and Squamous Cell Carcinomas

Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are the 2 most common types of nonmelanoma skin tumors. Clinical or histopathological diagnostic challenges are encountered on occasion. CD56 and smooth muscle actin (SMA) are highly expressed in BCCs. We aimed to investigate the frequency of these markers, along with B-cell lymphoma 2 (Bcl-2) and Ki67. This study was conducted to propose a method that could possibly be of diagnostic value. One hundred twenty-eight BCC and 39 SCC cases were included in this study. CD56, SMA, Bcl-2, and Ki67 immunohistochemical stains were applied. Ninety-nine (77.3%) BCC and 6 (15.4%) SCC cases showed CD56 immunoreactivity. SMA expression was detected in 78.1% of BCC and 5.1% of SCC cases. CD56, SMA, and Bcl-2 expressions were significantly higher in BCC cases. The Ki67 proliferation index was found significantly higher in SCC cases. When basosquamous carcinoma cases were compared with SCC cases, a significant correlation between tumors and expression of CD56, SMA, and Bcl-2 were obtained. CD56 and SMA, in addition to Bcl-2, favor BCC. Ki67 should also be included in the panel to demonstrate the proliferative activity.