Late-Onset Hemophagocytic Lymphohistiocytosis in a Lung Transplant Patient: A Case of T-Cell Post-Transplant Lymphoproliferative Disorder

Objective: Rare disease Background: Hemophagocytic lymphohistiocytosis (HLH) is a rare and life-threatening syndrome that can occur either in genetically predisposed individuals (primary HLH) or in particular conditions in immunocompromised patients (secondary HLH). Secondary HLH is very rare among solid organ transplant recipients, especially in lung transplant recipients, for whom its prognosis is dismal. Case Report: We report an exceptional case of HLH occurring unusually late following lung transplantation. At 11 years after transplantation, the patient, aged 67 years, presented with pancytopenia, fever, hyperferritinemia, and hypertriglyceridemia, along with splenomegaly. Exhaustive serological and PCR tests ruled out active infection. Bone marrow aspirates showed signs of hemophagocytosis, and bone marrow biopsy was suggestive of post- transplant lymphoproliferative disorder (PTLD). Timely treatment with etoposide and corticosteroids led to a transient improvement in the patient's clinical condition, and rituximab was initiated as a treatment for PTLD. Unfortunately, pancytopenia persisted for weeks, and the patient died from refractory septic shock, despite appropriate intravenous antibiotics. Autopsy revealed lymphoid infiltration of the mediastinal lymph nodes, liver and bone marrow, with some lymphocytes expressing CD3. A final diagnosis of Ann-Arbor stage IV non-EBVmediated monomorphic T-cell PTLD was established. Conclusions: This case report highlights a very unusual and fatal presentation of HLH in a lung transplant recipient, secondary to a T-cell PTLD. Indeed, HLH is typically seen as infection-related and reported to occur in the initial months following transplantation. To date, no guidelines or consensus exist regarding the management of immunosuppression regimen in solid organ transplantation.