Stromal immunohistochemistry of the smooth muscle actin expression in indolent versus aggressive basal cell carcinoma

Background Basal cell carcinoma (BCC) is often locally aggressive but rarely metastasizes. Detection of aggressive BCCs at an early stage is mandatory to avoid localized destruction, which causes disabilities to patients; several factors are associated with a more aggressive clinical course. Actin, which is found exclusively in normal epithelial cells, is substantially responsible for cell motility. The actin expression of some cancers may be changed, allowing for more aggressive invasion. Objective To evaluate the relevance of alpha-smooth muscle actin (α-SMA) as a BCC aggressiveness marker, regarding its expression in tumor cells as well as the surrounding stroma. Patients and methods This cross-sectional descriptive study was carried out on skin biopsies that were obtained from 36 patients with BCC for routine histopathological and immunohistochemical study to evaluate the reactivity of α-SMA. Results The reactivity of α-SMA was noticed in 88.9% of BCC cases. Tumoral α-SMA positivity was found in 63.2% of indolent BCCs and in 76.5% of aggressive BCCs. Stromal reactivity was found in 31.6% of indolent BCC cases and in 76.5% of aggressive BCC cases. There was a statistically significant difference between the indolent and aggressive groups in terms of stromal positive α-SMA. However, there was no statistically significant difference between the indolent and aggressive groups in terms of the intensity of expression of tumoral α-SMA. Conclusion Our study findings suggested that stromal α-SMA expression is an accurate and reliable marker of aggressiveness in BCC.