DETECTION OF EPSTEIN-BARR VIRAL-RNA IN MALIGNANT-LYMPHOMAS OF THE UPPER AERODIGESTIVE TRACT

Recent studies have suggested a probable etiologic association between Epstein-Barr virus (EBV) and nasal lymphomas, irrespective of geograp hic location. This study was performed to investigate the strength of association of EBV with non-Hodgkin's lymphomas of the upper aerodiges tive tract, based on a large series of cases that have been thoroughly immunophenotyped on frozen tissues. A sensitive in situ hybridization technique was used to detect EBV encoded RNA (EBER) in paraffin secti ons. Among 30 cases of nasal/nasopharyngeal T-cell lymphoma, 25 (83.3% ) were EBER-positive. In the positive cases, most of the neoplastic ce lls showed strong nuclear signals. Further analysis of this group of t umors showed that all 21 cases (100%) with a CD56+ CD3- phenotype were EBER positive, whereas four of nine cases (44.4%) with a CD56-negativ e immunophenotype were positive. Only one of 10 cases (10%) of nasal/ nasopharyngeal B-cell lymphoma was EBER positive; the positive case wa s a diffuse mixed-cell lymphoma and could not be distinguished morphol ogically from the negative cases. Among the 21 cases of lymphoma of th e tonsils and back of the tongue (20 B-lineage and one T-lineage), non e was EBER positive. In the normal mucosa of the nose/nasopharynx or t onsil (20 cases studied), only very rare EBER-positive small lymphocyt es were found in two cases. The almost exclusive detection of EBER in nasal/nasopharyngeal T-cell neoplasms among the lymphomas of the upper aerodigestive tract suggests that EBV probably plays an etiologic rol e in the pathogenesis of this group of tumors and is not simply a pass enger virus, and neither is this merely a site-dependent phenomenon in view of the weak association with nasal/ nasopharyngeal B-cell lympho ma.