Two young adult cases of Epstein-Barr virus associated-hemophagocytic lymphohistiocytosis with monoclonal proliferation of virus-infected cells within a short period after primary infection

Hemophagocytic lymphohistiocytosis (HLH) is a rare but severe complication of Epstein-Barr virus (EBV) infection. Interactions between EBV-infected T cells and activated macrophages cause several conditions such as pancytopenia, liver dysfunction and coagulopathy. We describe here two young adults with EBV-associated HLH with monoclonal proliferation of EBV-infected T cells within a short period after infectious mononucleosis as a primary infection. One patient was a 16-year-old man who developed severe pancytopenia and liver dysfunction two months after infectious mononucleosis. Bone marrow examination showed hemophagocytosis, and laboratory data demonstrated monoclonal proliferation of EBV-infected T cells. Several treatments such as immunosuppressive therapy, chemotherapy and hematopoietic stem cell transplantation were not effective, and the patient died of progressive disease. The other patient was a 19-year-old woman who developed thrombocytopenia and liver dysfunction two months after infectious mononucleosis. Findings of hemophagocytosis and monoclonal proliferation of EBV-infected T cells were similar to those in the first case. Clinical signs and symptoms were resolved completely by immunosuppressive therapy containing methyl-prednisolone and cyclosporine. Since these two cases each demonstrated a distinct clinical course, an investigation of the prognostic factors and treatment strategies for EBV-HLH is warranted.