Reactivation of Hemophagocytic Lymphohistiocytosis Triggered by Antithymocyte Globulin.

A 16-year-old boy with Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (HLH) underwent allogeneic hematopoietic stem cell transplantation after conditioning with fludarabine, melphalan, total body irradiation, and rabbit antithymocyte globulin (ATG). A severe, persistent infusion reaction occurred after the initial administration of ATG. Investigations showed a rapid increase in the levels of liver enzymes and ferritin, and the reactivation of HLH was confirmed by marked hemophagocytosis in the bone marrow. Treatment with pulse glucocorticoid therapy resulted in the improvement of HLH. This is the first case of HLH reactivation triggered by ATG. Physicians should therefore be cautious of HLH reactivation, especially when a severe and prolonged infusion reaction occurs.