Significance of keratin 13 and 6 expression in normal, dysplasic and malignant squamous epithelium of pyriform fossa.

It has been suggested that cytokeratin 13 is a useful marker of malignancy. We examined normal squamous cell epithelia, hyperplasia, dysplasias of various grades, intraepithelial neoplasia and invasive squamous cell carcinomas of the pyriform fossa using K13 and KL1. Positive staining for K13 was seen in all normal or hyperplastic benign epithelia, was inconstant in dysplasia, and intraepithelial neoplasia and carcinoma was negative. KL1 expression is constant and non significant. These results suggest that tumour cells are unable to synthesize keratin 13 a finding which may be valuable in surgical pathology.