Alpha smooth muscle actin (αSMA) immunohistochemistry use in the differentiation of pancreatic cancer from chronic pancreatitis

Aim: Fibrosis is observed both in pancreatic cancer (PDAC) and chronic pancreatitis (CP). The main cells involved in fibrosis are pancreatic stellate cells (PSCs), which activate alpha smooth muscle actin (alpha SMA), which is considered to be the best-known fibrosis marker. The aim of the study was to evaluate the expression of the alpha SMA in patients with PDAC and CP as the possible differentiation marker. Methods: We enrolled 114 patients undergoing pancreatic resection: 83 with PDAC and 31 with CP. Normal fragments of resected specimen from 21 patients represented the control tissue. The immunoexpressions of alpha SMA were detected in tissue specimens with immunohistochemistry (Abcam antibodies, GB). Results: Mean cytoplasmatic expression of alpha SMA protein in PDAC stromal cells was significantly higher compared to CP: 2.42 & PLUSMN; 0.37 vs 1.95 & PLUSMN; 0.45 (p < 0.01) and control group 0.61 & PLUSMN; 0.45 (p < 0.01). Strong immunoexpression of the alpha SMA protein was found in the vast majority (80.7%) of patients with PDAC, in about half (58%) of patients with CP, and not at all in healthy tissue. The expression of alpha SMA of different intensity was found in all patients with PDAC and CP, while in healthy tissue was minimal or absent. In PDAC patients, alpha SMA expression was significantly higher in tumors of diameter higher than 3 cm compared to smaller ones (p = 0.017). Conclusions: Presented findings confirm the significant role of fibrosis in both PDAC and CP; however, they do not confirm the role of alpha SMA as a marker of differentiation.