Dermatológia pre prax 3/2014

Immunohistochemical expression of smooth muscle actin in basal cell carcinoma of the skin

Purpose: Smooth-muscle actin alpha (α-SMA) is a marker of mesenchymal (muscle) and myoepithelial origin of the cells, however, its expression may be occasionally also observed in some epithelial tissue and tumors derived therefrom. In our study, we evaluated an immunohistochemical expression of α-SMA in basal cell carcinoma (BCC) of the skin. Material and methods: Study group consisted of 22 cutaneous BCCs from 19 patients (11 men, 8 women), in which α-SMA was detected immunohistochemically in biopsy examination. Results: α-SMA positivity in tumor cells was found in 16 carcinomas (72,7 %) and it varied between 2 – 90 % of cancer tissue. Five cases (22,7 %) exhibited a significant α-SMA immunoreactivity in a surrounding peritumorous stroma. Coexpression of α-SMA in cancer and adajcent stroma was present in 3 carcinomas (13,6 %). In most cases, „α-SMA positive“ tumor cells were accentuated at the periphery of tumor nests. In mixed histological BCC types, an immunoreactivity was usually irregular and different in the individual compartments. Among eight BCCs, which had an infiltrative growth component, five of them (62,5 %) showed a marked α-SMA expression in the peritumorous stroma. Such stromal positivity was found only in BCCs with infiltrative growth features, while α-SMA immunoreactivity in tumor was more or less reduced. Conclusion: Expression of α-SMA in cancer cells of cutaneous BCC is a frequent finding. Although its biological significance is not yet definitively clarified, it most likely plays a role in acquiring of more aggressive tumor phenotype. The results of our study may suggest, that infiltrative growth of BCC is accompanied by more extensive production of α-SMA in the surrounding peritumorous stroma, which probably modifies a growth and biological behavior of cancer.

Keywords: basal cell carcinoma of the skin, alpha-smooth muscle actin.