The role of α-smooth muscle actin in confirming the microinvasion of laryngeal squamous cell carcinoma

Abstract

BackgroundThe diagnosis of microinvasive laryngeal squamous cell carcinoma (mLSCC) is not always straightforward and sometimes can be very challenge in daily clinical practice, particularly in the circumstances with differentials such as SIL with inverted growth pattern and PEH. The focus of the diagnosis is the con rmation of microinvasion. Cancer-associated broblasts (CAFs), as the major element of tumor microenvironment, are believed to participate actively in the invasion of tumor cells. In this study, we sought to evaluate the diagnostic role of α-SMA labelling CAFs in mLSCC, with comparison of laryngeal squamous intraepithelial lesion (SIL) and benign pseudoepitheliomatous hyperplasia (PEH). MethodsA total of 81 laryngeal biopsy specimens were retrieved, including 41 cases of mLSCC with depth of invasion no more than 3 mm, 20 laryngeal SIL, and 20 PEH. All tissues were stained for immunohistochemistry, using antibody against the α-SMA antigen. We observed the presence of α-SMA positive broblasts in mLSCC, compared the results with that of laryngeal SIL and benign PEH by Chisquare statistics test, and investigated the correlation between tumor histological characteristics and the presence of CAFs in mLSCC. ResultsImmunoreactivity of α-SMA was detected in twenty-nine mLSCC (29/41, 70.7%), while no reactivity was observed in laryngeal SIL (0/20, 0%), and few in PEH (2/20, 10%). The α-SMA expression pattern in stromal broblasts of mLSCC were signi cantly different from those of SIL (χ 2 = 26.966, p=0.000) and PEH (χ 2 = 19.838, p=0.000). This support that, α-SMA as an immunolabeling of CAFs plays a reliable role in con rming the microinvasion of LSCC. In addition , we nds that there is dense lymphoplasmacytic in ltration in the stroma of a few mLSCC (7/41, 17.1% ) cases rather than tumor-related desmoplastic hyperplasia. And it seems that there is a negative correlation between dense lymphoplasmacytic in ltration and the presence of CAFs in LSCC. ConclusionsOur study highlights practical role of utilizing α-SMA in the diagnosis of microinvasive laryngeal squamous cell carcinoma, with emphasis on variable histomorphologic features of mLSCCs.