Immunohistochemical Distribution of Myofibroblasts in Oral Squamous Cell Carcinoma, Verrucous Carcinoma and Oral Epithelial Dysplasia”

Abstract

Background: Squamous cell carcinoma (SCC) is the most frequent type of oral malignancy that exhibits certain histological variations
and is associated with a high mortality rate .Verrucous carcinoma (VC) is considered to be an uncommon exophytic distinctive
low-grade well differentiated pathological variant of OSCC. Several studies have shown that the microenvironment or stroma of
neoplastic tissues plays an active role in tumor progression. Concurrent with the conversion of non-diseased epithelial tissue to
pre-cancerous epithelium to carcinoma, the stroma also changes from normal to primed’ to activated or tumor associated’.
Objective: The aim of this study was to compare the distribution of myofibroblasts in normal oral mucosa, oral epithelial dysplasia,
verrucous carcinoma, and different histological grades of OSCC.
Materials and methods: Twenty four formalin –fixed, paraffin -embedded tissue blocks (10 cases oral squamous cell carcinoma, 8
cases oral epithelial dysplasia and 6 cases verrucous carcinoma) were included in this study. An immunohistochemical analysis was
performed using anti alpha - smooth muscle actin (a- SMA) monoclonal antibody.
Results: All cases of OSCC, intraoral dysplasia and verruous carcinoma, and normal oral mucosa showed positive reaction of actin in
the stromal smooth muscles surrounding blood and lymphatic vessels. All OSCCs demonstrated stromal immunostaining for a-SMA
with different scores indicating the presence of myofibroblast. There were no myofibroblasts in the stroma of normal mucosa,
epithelial dysplasia or verrucuos carcinoma samples indicated by negative a-SMA expression in them.
Conclusion: The lack of myofibroblasts in normal, dysplastic oral epithelium and VC and their appearance in OSCC, suggests that
the genetically altered epithelium (carcinomatous epithelium), besides the invasive behaviour of OSCC may have an inductive
effect on the adjacent stroma to produce myofibroblasts.
Key words: Dysplasia,Verrucous Carcuinoma, Oral Squamous Carcinoma, a-SMA