Case Report: A three-year-old female patient, who underwent liver transplantation from her father due to biliary atresia one year prior, presented with fever and pancytopenia. Previous medical history indicated EBV PCR positivity three months ago, prompting a reduction in immunosuppression (RIS) with tacrolimus and administration of valganciclovir. Physical examination revealed lymphadenopathies in the cervical, axillary, and inguinal regions, spleen enlargement (5 cm), and fever of 39.0°C. Laboratory tests showed abnormal hemoglobin (6.8 g/dL), WBC (3.24x10^3/µL), platelet count (68x10^3/µL), MCH (mean corpuscular hemoglobin) - 22.7 pg, MCV (mean corpuscular volume) - 68.7 fL, MCHC (mean corpuscular hemoglobin concentration) - 33%, and ANC (absolute neutrophil count) - 0.9x10^3/µL. Biochemical parameters were normal except for elevated LDH (1623 U/L) and uric acid (8.5 mg/dL). EBV PCR revealed EBV PCR - 5 X10^4 copies/ml. Tacrolimus trough level was 13.7 µg/L at admission.
Radiological imaging revealed multiple lymphadenopathies in bilateral parailiac, mesenteric, cervical, axillary, paratracheal, pretracheal, subcarinal, and hilar regions. PET-CT showed increased FDG uptake in multiple lymph nodes across various regions. Excisional biopsy of the axillary lymph node revealed ‘Monomorphic post-transplant lymphoproliferative disorder with plasmablastic lymphoma phenotype’ characterized by widespread strong positivity for CD138 and CD79a, focal positivity for EBER, Ki-67 proliferative activity of 90%, and negativity for various markers. Immunohistochemically, neoplastic cells exhibited predominant positivity for lambda and negativity for kappa, consistent with lambda clonality. Biopsy material was negative for t(11/14) and t(14/18). Bone marrow aspiration and biopsy showed no lymphoma infiltration but revealed increased histiocytes and hemophagocytosis, leading to suspicion of hemophagocytic lymphohistiocytosis (HLH) in addition to plasmablastic lymphoma. Based on laboratory findings and diagnostic criteria, the patient was diagnosed with Plasmablastic Lymphoma Type-Monomorphic PTLD leading to secondary HLH. Treatment included reduced immunosuppression with sirolimus, induction therapy, and CHOP chemotherapy plus rituximab. Additionally, intravenous immunoglobulin therapy was initiated for HLH treatment. Following treatment, lymphadenopathy and splenomegaly resolved, blood tests normalized, and EBV PCR became negative.
Conclusion: Plasmablastic Lymphoma (PBL) is a rare and aggressive type of Non-Hodgkin lymphoma, often associated with immunocompromised states such as HIV infection. Our case represents a rare instance of PBL occurring as a post-transplant lymphoproliferative disorder in a pediatric patient, complicated further by secondary HLH. Despite the aggressive nature of PBL-PTLD, positive response to therapy suggests a favorable prognosis, although further observation is warranted.