Histochemical and Immunohistochemical Analysis of Collagen Fibers and Microvascular Density in Various Grades of Oral Submucous Fibrosis

Background and Objective: This study was aimed to evaluate the collagen fibers qualitatively and its correlation with microvascular density in various grades of oral submucous fibrosis (OSMF).   Material and Methods: The present study comprised of total 40 cases of oral submucous fibrosis. Picrosirius red staining was done on all the specimens’ sections. They were analyzed for the colour and orientation of collagen fibers. Morphometric measurements were done using image analysis on immunohistochemical stained sections for Factor VIII-related antigen and analyzed for microvascular density. Results: Picrosirius red polarizing microscopy results revealed that there was a shift in the colour of collagen fibers from greenish yellow to orange red and red colour as the severity of the oral submucous fibrosis increased. The collagen fibers showed mixed orientation in early oral submucous fibrosis and parallel orientation in advanced oral submucous fibrosis. There was a significant decrease in microvascular density from early to advanced oral submucous fibrosis. Conclusion: The change in the colours and orientation of collagen fibers in early and advanced oral submucous fibrosis could be attributed to the fibre thickness, type of collagen, alignment and packing, cross-linking of the fibers and the section thickness. However, in advanced cases the vascularity is reduced which may predispose to epithelial atrophy and subsequent malignant changes.