Clinicopathological landscape of pediatric monomorphic PTLD: national retrospective study

INTRODUCTION: The diagnosis and management of monomorphic post-transplant lymphoproliferative disorder (mPTLD) require a multidisciplinary approach. This study describes clinical characteristics, diagnostic approach, therapeutic strategy and outcome of mPTLD after solid-organ transplant (SOT) in Spain. PATIENTS AND METHODS: National retrospective observational study in children and adolescents with mPTLD following SOT. All pediatric oncology centers performing SOT were contacted. Data from January 2000 to December 2023 were collected. RESULTS: Thirty-seven patients from 8 out of the 10 centers with a SOT program were included, 57% were male, the median age at transplant was 4.3 years (range, 0.3-16.9), and the median age at diagnosis was 10.9 years (range, 1.7-17.2). The most commonly transplanted organ was the liver (29.7%). Eighty-eight percent of patients had symptoms, most frequently gastrointestinal (37.5%), with both nodal and extranodal involvement in 51.4% patients. Seventy-six percent of patients had stage III-IV disease. The first imaging test was performed 2.5 days (range, 0-45) from clinical suspicion, and PET/CT was used in 59.5% patients: for diagnosis (90.9%), assessment of treatment response (59.1%) or follow-up (45.5%). Immunosuppression was reduced in 97.2%, rituximab in monotherapy and low-dose (immune)chemotherapy was given in 21.6% patients, respectively, and high-intensity chemotherapy in 54.1%. The median follow-up was 6.8 years (range, 0.0-16.7), 18.9% patients died, and 19.4% experienced graft loss. Event-free and overall survival at five years were 80.2% and 82.9%, respectively. CONCLUSIONS: The absence of consensus guidelines to follow conveys differences in the management of mPTLD in Spain. Descriptive analysis of this situation acknowledges the need to create consensus protocols on how to suspect, diagnose and treat this rare disease. These data will contribute to the development of national guidelines for the management of mPTLD.