Stromal myofibroblasts in oral squamous cell carcinoma and potentially malignant disorders

Concurrent with the progression of a non- diseased epithelium to the pre-cancerous epithelium to carcinoma, the stroma also undergoes modifications. Myofibroblasts are important stromal cells that play a crucial role in carcinogenesis. The current study investigated the presence of myofibroblasts in healthy oral mucosa, potentially malignant disorders (PMDs) and squamous cell carcinoma (SCC).

The study material consisted of a total of 106 samples categorized into three groups, namely, Group I - Oral SCC (OSCC) (n = 42), Group II - PMDs (n = 32) and Group III - Oral healthy mucosa (n = 32) subjected to immunohistochemical analysis using alpha Smooth Muscle Actin.

Among the 42 cases of OSCC, the staining index was negative in 23 cases (54.7%), low in 9 cases(21.4%) and moderate in 10 cases (23.8%). The stroma of cases of verrucous carcinoma, cases of Hyperkeratosis with epithelial dysplasia, 77.5% of the cases of oral Submucous Fibrosis (OSMF) and healthy oral mucosa were devoid of myofibroblasts resulting in a grade of "0" in all cases.Two of the cases of OSMF (12.5%) showed low staining index for myofibroblast. There was a significant difference in the myofibroblasts expression between the Groups (Kruskal-Wallis test P<0.001).

The findings of the current study justify "myofibroblast" as one among the key stromal element in tumor progression. Future studies involving a larger sample size along with follow up of patients with PMDs are essential to identify the exact stage in which they emerge in the stroma of these lesions.