[Chronic active EB virus infection accompanied by monoclonal proliferation of granular lymphocytes]

An 18-year-old man was admitted to our hospital because of 39 degrees C fever for over one month, marked hepatosplenomegaly, and pancytopenia. Malignant histiocytosis, malignant lymphoma, or hemophagocytic syndrome were ruled out by bone marrow aspiration and liver biopsy. A diagnosis of chronic EB virus infection was made according to his characteristic clinical features, abnormally high titiers of anti-EBV antibodies (VCA-IgG x 2560, EA-IgG x 1280), and the detection of EBV genome in the peripheral blood mononuclear cells by polymerase chain reaction. He also manifested granular lymphocyte proliferative disorder (GLPD). The phenotype of the proliferating granular lymphocytes was CD2 (+), CD3 (-), CD56 (+), and IL-2R beta (+), showing the NK lineage of these cells. Chromosomal abnormality of the cells cultured for a short time with IL-2 and a monoclonal junctional DNA structure of EB virus terminal repeat analyzed by the Southern blotting provided definitive evidence for the monoclonal expansion of the granular lymphocytes. These findings indicate a causative role of EV virus in NK-GLPD or NK-leukemia.