IntroductionPost-transplant lymphoproliferative disorders (PTLDs) comprise a heterogeneous group of Epstein-Barr virus (EBV)-positive or negative lymphoid or plasmacytic lesions in solid organ or hematopoietic stem cell (HSC) transplant recipients. Although PTLDs in adults have been extensively studied, the clinicopathologic features of monomorphic B-cell PTLD in children, particularly EBV-negative forms, are still poorly understood.MethodsWe retrospectively reviewed all our pediatric cases of monomorphic B-cell PTLDs diagnosed in the past 10 years. Clinical data were reviewed. Pathologic data including histologic types and EBV status were analyzed. Additional immunohistochemical stains, FISH studies, and TP53 gene mutational status were performed.Results4 of 18 cases were EBV-negative. All 4 EBV-negative cases were strikingly confined to the gastrointestinal (GI) tract or abdominal lymph nodes, while tumors in EBV-positive cases were found at various anatomic sites; 2 of 4 EBV-negative cases carried mutations in TP53 gene. Our cohort also included 2 rare types of PTLD, one plasmablastic lymphoma and one high-grade B-cell lymphoma, not otherwise specified (HGBL, NOS).ConclusionWe report that monomorphic B-cell PTLDs in children have distinctive clinical and pathological features. More studies are needed to clarify whether and how much these pediatric PTLDs differ from their adult counterparts.