CLINICOPATHOLOGICAL STUDY OF NASAL T NK-CELL LYMPHOMA AMONG THE JAPANESE/

A high prevalence of nasal lymphoma expressing a T- or natural killer (NK)-cell phenotype (NTCL) with frequent association of Epstein-Barr v irus (EBV) has been indicated in Asians. To characterize NTCL among th e Japanese, the clinicopathologic features of 32 cases were evaluated and the cases were also analyzed for EBV-RNA using an ISH method. Morp hologically, 31 cases were identified by atypical pleomorphic lymphoid infiltrates with polymorphous, angicentric, and necrotic features. Th eir lymphoma cells ranged in size from small to large and were mixed I n varying proportion from case to case. The other one case showed a mo nomorphic 'blastic' appearance. EBV-encoded small RNA (EBER) was detec ted in the neoplastic cells of 27 of the 32 cases examined. In the fiv e EBV-negative cases, one was the 'blastic' type. Clonal T-cell recept or gene rearrangement was detected in none of seven cases examined. Th e patients had a median follow-up of 9 months (range, 1 month to 14 ye ars and 11 months). The Kaplan-Meier estimate of overall survival was 49% at 5 years, correlating with clinical stage. These data support th e concept that most cases of NTCL are identified as tumors with T/NK-c ell characteristics and EBV association, distinctly different from oth er peripheral T-cell lymphomas. Furthermore, the one case of an EBV-ne gative 'blastic' variant appears not to fit well into the pleomorphic category but more closely resembles the pathologic features of extrana sal angiocentric lymphoma with lymphoblastoid appearance. This study a lso showed no clear difference in clinical aspects other than the orig inal site or in prognosis, between NTCL and extranasal angiocentric ly mphomas despite the higher incidence of EBV association and the tenden cy for that peculiar anatomical site to be restricted to the former gr oup.