The prognosis of oral mucosal squamous cell carcinomas: a comparison of clinical and histopathological grading and of laminin and type IV collagen staining.

Changes in the distribution of basement membrane components have been described in dysplastic lesions and in oral mucosal squamous cell carcinomas (OMSCC). The purpose of this study was to determine if these changes were related to pathological grade and if so, whether this had prognostic implications. Fifty formalin-fixed, paraffin-embedded specimens of OMSCC, with five or more years clinical follow-up, were studied using an immunoperoxidase technique for the detection of the basement membrane components, laminin and type IV collagen. The immunoreactivity of each component was evaluated and semiquantitatively scored as minimal, moderate or extensive and the results compared with the tumour size, node involvement and metastasis (TNM) clinical staging system and histopathological features. OMSCC were characterized by minimal or moderate staining with small islands of neoplastic cells frequently lacking staining for laminin and type IV collagen. Deposition of these components decreased with increased histopathological grade and absence of staining was more commonly associated with a poor prognosis. In particular the pattern of type IV collagen staining frequently differed from laminin staining. Neither of these parameters offered an advantage over TNM clinical staging with regard to prognosis. It was concluded that variations in laminin and type IV collagen immunoreactivity occurred in OMSCC and that high histopathological grade tumours with considerably diminished staining with anti-laminin and anti-type IV collagen carried a poor prognosis.