Undifferentiated nasopharyngeal carcinoma (U-NPC): Immunohistochemical study of adhesion molecules

CU-NPC is an important clinical entity that presents some uncertainties regarding histologic features. In fact many of these tumors show a marked infiltration of lymphocytes justifying the term "lymphoepithelioma" used to define these tumors in the past. Although they have not yet been placed in a definite category, some factors may be responsible for the lymphocyte infiltration; infection by Epstein-Barr virus, expression by tumor cells of HLA-DR antigens and intercellular adhesion molecules (ICAM-1) and production of interleukin l-alpha by U-NPC derived cell lines. A recent study showed that epithelium of the crypts of the tonsils exerts an active role in the intraepithelial migration of lymphocytes. This recruitment from the underlying lymphatic tissue could be determined by the expression, on the part of the basal cells of tonsillar crypts, of ICAM-1 and blood vessel adhesion molecules (VCAM-1). The purpose of this study was to verify the presence of ICAM-1 and VCAM-1 in paraffin-embedded tissue section of seven cases of U-NPC. The results showed positive immunohistochemical reaction both for ICAM-1 and VCAM-1. On this basis, the authors hypothesize that the expression of these molecules could favor intratumoral recruitment of lymphocytes similar to what occurs in the epithelium of the tonsillar crypts.