Squamous cell carcinoma of the tonsillar region and the base of the tongue: a morphological and immunohistochemical comparative pilot study.

Sixteen squamous cell carcinomas of the tonsillar region and 13 carcinomas of the base of the tongue were studied in a search for significant differences between the tumours of these two oropharyngeal subsites, which are known to carry a significantly different prognosis. The characteristics of the tumour cells and the tumour-host relationship were scored on H & E-stained slides, as well as on slides stained with a panel of antibodies. The results obtained were cross-tabulated and analysed with respect to the subsite. Ten variables were tested: cytonuclear pleomorphism, mitotic activity, the presence of atypical mitoses, keratinization, tumour grade, presence of eosinophils, severity of inflammatory response, and the expression of keratin-10, blood group antigens and collagen IV. When split up by site, only cytonuclear pleomorphism revealed a significant difference, tonsillar carcinomas more often exhibiting marked pleomorphism (p = 0.04). Despite having some prognostic relevance for squamous cell carcinomas of the head and neck, the variables tested could not provide an explanation for the difference in biological behaviour of the tumours studied.