Collagen characterization in different patterns of bone invasion by OSCC: A histochemical study with picrosirius red and polarizing microscopy

IntroductionCollagen, the most abundant protein in the body, is not only responsible for maintaining the functional integrity of tissues but is also thought to play an important role in pathogenesis and invasion in oral squamous cell carcinoma (OSCC).AimThe study aimed to assess the thickness as well as maturation of collagen fibres in erosive and infiltrative patterns of OSCC in order to determine the possible role of stromal components (collagen) in bone invasion.Materials and methodsHistometric analysis was performed on 1350 collagen fibres in 14 cases of OSCC exhibiting either an erosive or an infiltrative pattern of mandibular invasion using polarizing microscope under oil immersion. Two consecutive sections of 5 μm thickness from each sample were taken and stained with haematoxylin and eosin (H&E) and picrosirius red stain, respectively, to enable visualization and counting of thickness of fibres.ResultsA significantly higher percentage of thick fibres and a greater amount of green/no colour birefringence were observed in cases of OSCC that exhibited an infiltrative pattern of bone invasion.ConclusionThe stromal component plays an important role in the biological behaviour of a tumour. It is probable that in OSCC the infiltrative pattern of bone invasion induces increased production of loosely packed procollagens, intermediates, or pathological collagen which further aids in the invasion of the tumour into the surrounding bone, worsening the prognosis.