AN IMMUNO-CYTOCHEMICAL STUDY OF THE DISTRIBUTION OF EPITHELIAL MEMBRANE ANTIGEN IN NORMAL AND DISORDERED SQUAMOUS EPITHELIUM

Abstract

Using immunocytochemical techniques the distribution of epithelial membrane antigen (EMA) in human squamous epithelium was studied. The antigen is not demonstrable in normal adult tissues although it is present on the surface membrane of normal fetal epidermis before keratinization takes place. It may be expressed strongly in the adult in in situ and infiltrative squamous carcinomas and in a variety of non-neoplastic states. EMA may protect exposed surfaces. The lack of demonstrable antigen on malignant melanomas and basal cell carcinomas highlights the histogenetic differences between these tumors and squamous carcinomas and suggests a possible role for EMA in the differential diagnosis of malignant skin tumor.