A Histopathological and Immunohistochemical Study of Basal Membrane Alterations, with Special Reference to Advance of Dysplastic Grading

A histopathological and immunohistochemical study was conducted to elucidate the alteration of the basement membranes (BMs) and important related factors in oral precursor lesions and oral squamous cell carcinoma (OSCC). Gingivae from 36 cases (5 normal epithelium, 7 hyperkeratosis, 7 mild dysplasia, 7 moderate dysplasia, 5 severe dysplasia, 5 OSCC) were examined. As for histopathological findings of BMs, periodic acid-methenamine-silver stain (PAM) displayed continuous liner appearances in all cases except for OSCC. Reticulin silver impregnation showed discontinuous and irregular distributions were admitted in severe dysplasia and OSCC. From immunohistochemical analysis, laminin 5γ2 and collagen IV appeared thicker and more irregularity attitude in moderate, severe and OSCC, while thinner, linear and continuous appearance in control, hyperkeratosis and mild dysplasia. As for integrin α6, it was increased obviously from hyperkeratosis to mild dysplasia, but it was decreased in severe dysplasia and OSCC on the contrary. Expression of tenascin was gradually increased underlying BMs from hyperkeratosis to OSCC. As for oral precursor lesion, instability of BMs components and up-regulation of BMs related proteins have reinforced from moderate dysplasia. Based on these results, it was supposed that moderate dysplasia became the switch to malignant transformation occurs.