Histopathological evaluation of collagen fibers using picrosirius red stain and polarizing microscopy in oral squamous cell carcinoma

Abstract

Background: Collagen is a part of structural connective tissue in every organ of the body. Study of collagen brings into focus the current knowledge of biosynthesis and degradation as a complex mechanism. One of the major aspects of tumor cell invasion and metastasis is the interaction between cancer cells and extracellular matrix component. Property of picrosirius red to enhance the birefringence is the result of basic protein nature of collagen molecules. There exists a direct relationship between the presence of type IV collagen and degree of differentiation in squamous cell carcinoma (SCC) cells as they lose their capability to form the basement membrane. Materials and Methods: Thirty cases of oral SCC (OSCC) were evaluated for standard staining protocol of picrosirius red to analyze collagen fibers in different grades of OSCC under polarizing microscopy. Results: In this study, moderately to poorly differentiated OSCC cases showed a gradual change in polarizing colors from yellowish orange to greenish yellow particularly in the vicinity of invading tumor islands. Thick collagen fibers forming bundles in parallel disposition were found around the neoplastic areas in discontinuous fashion. Type I collagen fibers of different lengths were strongly birefringent and swirl pattern, parallel orientation was evident. Conclusion: An observable stromal change with the progression of neoplasm was evinced with picrosirius red stain in different thickness of collagens with a significant change in the arrangement from the early stage to the advanced stage according to tumorogenesis.