Posttransplant Lymphoproliferative Disorder (PTLD): 24 Years of Experience at a Referral Center in São Paulo, Brazil. Can Differences in Prevalence and Subtype of EBV Infection in the Population Influence the Results? A Retrospective Cohort Study.

Objectives: To retrospectively review all cases of posttransplant lymphoproliferative disorder (PTLD) in a large Brazilian transplant center, describing patients' clinical, virological, and histopathological profiles and treatment strategies and prognostic factors. Methods: This retrospective cohort study was conducted between January 2000 and June 2024. Adult patients with confirmed PTLD following solid-organ or bone marrow transplant were included. Patients with other systemic cancers or on concurrent chemotherapy/radiotherapy were excluded. Clinical characteristics, PTLD prevalence, histopathology, and survival were assessed. Results: Thirty-eight cases of PTLD were identified in the 5928 transplant patients (0.6%). Incidence was highest in lung recipients (31%). Median time to PTLD onset was 42 months. EBV DNA was detectable in 54.8% of cases. Monomorphic PTLD was the most common (89.5%), primarily in non-Hodgkin lymphomas (91.2%). Immunotherapy (anti-CD20) and immunosuppression reduction were standard initial treatments. R-CHOP and rituximab monotherapy were the main first-line regimens. Age and treatment response significantly influenced overall survival. Mortality was 42%, mainly due to infections and disease progression. Conclusions: Despite the higher prevalence of EBV in Brazil, PTLD patterns and incidence were consistent with those found in developed countries. The strong association with lung transplants mirrors global data. Local EBV subtype characteristics and host immunogenetic factors warrant further investigation.