NASOPHARYNGEAL CARCINOMA IN-SITU - 2 CASES OF AN EMERGENCY DIAGNOSTICENTITY

BACKGROUND. The association of Epstein-Ban virus (EBV) with the oncoge nesis of nasopharyngeal carcinoma (nTPC) is well established. Latent i nfection by EBV with clonal proliferation has also been demonstrated i n preinvasive lesions of NPC. In situ hybridization for EBV-encoded RN A (ISH EBER) now serves as an ancillary test in the definitive diagnos is of these lesions. METHODS. Two cases of nasopharyngeal carcinoma in situ (NPCIS) are presented in this study. Their biopsies were studied by ordinary light microscopy, the ISH EBER technique, and immunostain ing for bcl-2. Tissue samples from 100 high risk subjects negative for NPC and NPCIS, who served as controls, were also studied using the IS H EBER technique. RESULTS. NPCIS was characterized by abnormal light m icroscopic appearance as well as positive staining by the ISH EBER tec hnique; these features were not observed in samples from the 100 high risk subjects. Immunostaining for bcl-2 protein was positive but less specific. Postradiotherapy biopsies of the two patients were negative for NPCIS. CONCLUSIONS. With the help of the ISH EBER technique, the d iagnosis of NPCIS is now possible in routine surgical pathology. As th is entity is rare, it is necessary to have a high degree of suspicion when evaluating biopsies from high risk individuals. Radiotherapy for patients with NPCIS is justified in View of the risk of cancer progres sion and the possibility of a coexisting invasive carcinoma. (C) 1998 American Cancer Society.