Immunohistochemical Expression of Mast Cells Using c-Kit in Various Grades of Oral Submucous Fibrosis

Oral submucous fibrosis (OSF) is a high risk precancerous condition characterized by changes in the connective tissue fibers of lamina propria and deeper parts of mucosa. Mast cells are local residents of connective tissue and have been identified to participate in fibrotic process. These cells produce pharmacologically active substances necessary for the physiological function of our body in response to various stimuli as and when required and also play a significant role in the pathogenesis of oral diseases. Ten healthy volunteers and 30 clinically diagnosed OSF cases with histopathological confirmation were included in the study. Immunohistochemical (c-kit) as well as acidified toluidine blue staining techniques were used to evaluate density and expression of mast cells. The mast cell density assessed using c-kit and toluidine blue showed significant difference in various stages of OSF. In general the mean number of mast cells obtained using c-kit was found to be more than that obtained using toluidine blue in various stages of OSF. The comparison of mast cell densities using immunohistochemistry (c-kit) and toluidine blue stain confirmed that c-kit is a more reliable technique to assess mast cell density in OSF. 1. Introduction Oral submucous fibrosis (OSF) is a chronic, progressive, and devastating disease which is prevalent in South East Asia. This is known to affect most parts of oral cavity, pharynx, and upper third of oesophagus. Although the pathogenesis of the disease is considered as multifactorial with areca nut chewing, ingestion of chilies, genetic and immunological processes, and nutritional deficiencies, areca nut is found to be the main aetiological factor for developing OSF [1]. In the initial stages, the disease is expressed clinically with burning sensation of mouth, blister formation, ulceration, excessive salivation, and defective gustatory sensation. As the disease progresses, the mucosa becomes blanched and fibrous bands appear vertically leading to difficulty in mouth opening [2]. Characteristic histopathological features of this disease include atrophic epithelium with an intercellular edema and moderate epithelial hyperplasia associated with progression of the disease. Many studies have revealed that mast cells play an important role in OSF as they have been identified to participate in fibrotic process. The pathogenic mechanism in OSF begins in the connective tissue region and mast cells are the local residents of the connective tissue. Studies on mast cells in normal and various pathological conditions have revealed them to