Abstract
BACKGROUND EBV-associated smooth muscle tumors (EBV-SMTs) are rare malignancies in pediatric transplant recipients under chronic immunosuppression, with fewer than100 cases reported globally. Diagnosis is challenging due to nonspecific imaging findings and overlapping features with other post-transplant malignancies, necessitating histopathological confirmation. This underscores the need for heightened clinical suspicion in high-risk cohorts. CASE REPORT Here, we present a pediatric case from our liver transplant (LT) center involving a patient who developed both post-transplant lymphoproliferative disorder (PTLD) and EBV-SMT following liver transplantation. Clinical data and comprehensive treatment details of this rare case were retrospectively reviewed. The patient, diagnosed with a congenital bile acid synthesis defect, underwent liver transplantation at the age of 5 months. Pre-transplant screening confirmed that both the donor and recipient were negative for cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infections. However, EBV DNA became detectable in peripheral blood at 22.5 months after transplantation and showed a progressive increase over time. At 30.9 months after LT, PTLD and hepatic EBV-SMT were simultaneously diagnosed through histopathological examination. Treatment strategies included stepwise immunosuppression reduction, administration of rituximab targeting PTLD, and subsequent sirolimus therapy for EBV-SMT and surgical resection of the liver and splenic tumor. This multidisciplinary approach successfully achieved complete remission. CONCLUSIONS EBV-SMT necessitates multidisciplinary management balancing immunosuppression with targeted therapies. mTOR inhibitors are a strategic option for concurrent rejection prevention and tumor control. Sirolimus, a mechanistic target of rapamycin (mTOR) inhibitor, demonstrates promise by simultaneously preventing rejection and inhibiting tumor progression.