Solid organ transplantation (SOT) is an effective treatment modality for children and young adults with end-stage organ failure with 5-year overall survival ranging from 25 to 95% depending on the transplanted organ. Patients subsequently require lifelong immunossupression to maintain graft health and limit the risk of graft rejection. Commonly used immunosuppressants to inhibit organ recipient T-lymphocyte function include calcineurin inhibitors (CNI), mTOR inhibitors, thiopurines, and antimetabolites. Most cases of monomorphic Post-Transplantation Lymphoproliferative Disorders (m-PTLD) are related to the Epstein Barr virus (EBV) and occur in patients who were EBV seronegative before the transplant.

Our aim is to assess the overall survival in patients diagnosed with monomorphic Post-Transplantation Lymphoproliferative Disorders after SOT.

We present retrospective data on 46 pediatric patients diagnosed with monomorphic Post-Transplantation Lymphoproliferative Disorders with Non-Hodgkin Lymphoma (NHL) after SOT in our Institution between 2001 and 2024.

Twenty four of the 46 were male, and 22 were female, and mean age at the time of diagnosis of PTLD was 8 years (age range, 11 months to 17 years). PTLD was diagnosed at a median time of 36 months after the organ transplant, with a significantly shorter interval in liver (20/46), 31 months, versus heart (15/46) or kidney (11/46) graft recipients (48- and 42-months years, respectively p < 0,05). Most common histopathology subtypes were Burkitt in 20/46 (44%), Diffuse Large B-cell lymphoma (DLBCL) in 19/46 (41%) and other NHL in 7/46 (15%). Most common sites were abdominal (17/46), followed by cervical and axillary lymph nodes (12/46). Murphy staging system revealed: Stage I (5/46 - 11%), Stage II (5/46 - 11%) and Stage III (33/46 -72%). Stage IV diseases with bone marrow (1/46 – 2%) and/or Central nervous system Involvement (CNS) (2/46 - 4%). The treatment carried out was reduction of immunosuppression and rituximab in 18 patients, with chemotherapy, rituximab and reduction of immunosuppression in 28 patients. In one relapse there was a need for bone marrow transplantation. No differences in outcome were observed between Early (22/46) and late-onset (24/46) PTLD and EBV-positive (14/46) or EBV-negative (25/46) PTLD, respectively. The 5-year overall and event-free survival were 91% and 83%, respectively.

The outcome of m-PTLD has clearly improved as a result of the introduction of more uniform treatment protocols and improved supportive care, instaging and response monitoring. The majority of had a good response with chemotherapy and/or rituximab.