EPSTEIN-BARR-VIRUS IN NASAL T-CELL LYMPHOMAS (POLYMORPHIC RETICULOSISMIDLINE MALIGNANT RETICULOSIS) IN WESTERN CHINA

Polymorphic reticulosis (PR) or midline malignant reticulosis (MMR) is considered to be malignant, or at least pre-malignant T-cell prolifer ations of the nose or midline area. Recent reports of small series of nasal T-cell lymphomas have shown a strong association with Epstein-Ba rr virus (EBV). Furthermore, a peculiar phenotype is described, with e xpression of CD56 and not of CD3, suggesting a possible origin from na tural killer (NK) cells. We have analysed a series of 38 cases of PR/M MR for the presence of EBV by in situ hybridization (ISH) of the EBV-e ncoded RNAs 1 and 2 (EBER). Twenty cases were tested for expression of EBV-encoded latent membrane protein 1 (LMP-1). Special attention was also paid to the expression of CD3 and the NK cell-related marker CD56 . Thirty-two cases (84 per cent) showed positive EBER ISH. In 5 of 20 cases, LMP-1 expression was detected. In three cases, a few scattered cells were positive, and in two cases, LMP-1 was detected in clusters of atypical cells. Most of the neoplasms showed expression of CD3 (89 per cent) and in 27 cases (71 per cent), CD56 was detected. These resu lts are consistent with an aetiopathogenetic role for EBV in most, but not all, cases of PR/MMR. Our findings are less supportive of a major role for LMP-1 in tumour genesis. CD3 expression in most of the cases of PR/MMR underlines the T-cell origin of these neoplasms, often with aberrant expression of CD56.