The association between carcinoma of the tonsil and Epstein-Barr virus--a study using radiolabelled in situ hybridization.

We reviewed 30 cases of carcinoma of the tonsil and classified them as squamous cell carcinoma, non-keratinizing differentiated carcinoma and non-keratinizing undifferentiated carcinoma. Five cases of non-keratinizing undifferentiated carcinoma were identified, and these, together with 5 cases of squamous cell carcinoma, were studied for the presence of Epstein-Barr virus by in situ hybridization using early RNA (EBERs) as probes. All cases of squamous cell carcinoma were negative for EBER and only one of the 5 cases of non-keratinizing undifferentiated carcinoma was positive. As a positive control we used a case of a primary nasopharyngeal carcinoma with extension to the tonsil. Though the tonsil and nasopharynx share similar anatomical and immunological features, we conclude that in the majority of cases EBV is not demonstrable in tonsillar carcinomas.