Allograft-localized post-transplant lymphoproliferative disorder in a pediatric kidney transplant recipient: a case report and focused review.

BACKGROUND: Post-transplant lymphoproliferative disorder (PTLD) is a serious complication of pediatric kidney transplantation. PTLD confined to the kidney allograft is uncommon, and optimal management in this setting remains uncertain. CASE PRESENTATION: An eight-year-old boy with chronic kidney disease stage G5D due to posterior urethral valves developed monomorphic PTLD limited to the kidney allograft one year after deceased-donor kidney transplantation. Histopathology demonstrated high-grade B-cell lymphoma of the activated B-cell phenotype, with negative Epstein–Barr virus DNA and low-level cytomegalovirus DNA without evidence of end-organ disease. In the absence of systemic disease, a multidisciplinary team pursued a graft-preserving strategy rather than upfront nephrectomy, consisting of reduction of immunosuppression and rituximab-based chemoimmunotherapy with cyclophosphamide, prednisolone, and rituximab (CPR). Despite treatment-related cytopenias and transient hemodialysis, the patient achieved complete metabolic remission on PET-CT and remains disease-free with preserved graft function at five years of follow-up. CONCLUSION: This case demonstrates that graft-preserving, risk-adapted chemoimmunotherapy can achieve durable remission in selected pediatric patients with allograft-localized PTLD while maintaining long-term kidney allograft function.