Epithelial membrane antigen expression in benign and malignant squamous epithelium of the head and neck

A distinction between benign, preneoplastic, and malignant tissue, based upon the expression of surface antigens, would provide useful clinical information. Epithelial membrane antigen (EMA) has been reported in squamous cell carcinomas, but not in normal squamous epithelium. Twenty-nine specimens from 15 patients, representative of the spectra of changes seen in squamous cell epithelium from normal through dysplasia to squamous cell carcinoma, were fixed in B-5 and examined with anti-EMA monoclonal antibody in an immunoperoxidase technique. Normal squamous epithelium does express EMA. Squamous cell carcinoma also expresses EMA. Well-differentiated tumors stain more intensely and in greater numbers of cells than less-differentiated tumors. The presence or absence of EMA expression does not distinguish normal squamous epithelium from carcinoma. Investigations of membrane antigen content in fixed tissue must use methods of fixation that preserve antigenicity. While strict quantitation of immunoperoxidase preparations is not possible, quantitative differences in expression may be important.