EBV-positive diffuse large B-cell lymphoma in young adults: is this a distinct disease entity?

Background: Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) of the elderly is defined only in adults older than 50 years. However, EBV-positive DLBCL can affect younger patients. We investigated the prevalence, clinical characteristics and survival outcomes of EBV-positive DLBCL in young adults. Patients and methods: We analyzed patients with de novo DLBCL who were registered in the Samsung Medical Center (SMC) retrospective lymphoma cohort and prospective SMC Lymphoma Cohort Study I (ClinicalTrials.gov: NCT00822731). Results: A total of 571 cases were included in the analysis. The prevalence of EBV positivity was 6.7% (13/195) and 9.3% (35/376) in the young group (<= 50 years) and in the elderly group (>50 years), respectively. EBV status was closely associated with unique unfavorable clinical characteristics [older age, more advanced stage, two or more sites of extranodal involvement, higher International Prognostic Index (IPI), and age-adjusted IPI risk] only in the elderly group. Poor prognostic impact of EBV positivity on overall survival was observed only in the elderly group [hazard ratio (HR) 2.86; 95% confidence interval (CI) 1.83-4.47; P < 0.001], but not in the young group (HR 1.17; 95% CI 0.35-3.89; P = 0.801). Conclusion: A substantial proportion of EBV-positive DLBCL of the elderly can occur in young adults. EBV positivity of DLBCL in young adults was not associated with unfavorable clinical characteristics or worse outcomes. We suggest that EBV-positive DLBCL should not be confined only in the elderly and 'EBV-positive DLBCL in young adults' needs to be considered as a clinically distinct disease entity.