To the Editor: The role of hepatitis C virus (HCV) and human herpesvirus 8 (HHV-8), two B-cell–tropic viruses, in B-cell proliferation¹ is illustrated by the following unusual case of plasma-cell leukemia. In 1995, a 32-year-old man with a history of hepatitis A virus and HCV infection but who tested negative for hepatitis B virus and human immunodeficiency virus was admitted to the hospital with septic shock, bilateral pneumonia, and hepatosplenomegaly. The hemoglobin level was 8.9 g per deciliter; the white-cell count was 26.6×10⁹ per liter with 50 percent plasmablasts (Figure 1A), 41 percent neutrophils, 7 percent lymphocytes, and 2 percent . . .