[Effective treatment for a methotrexate-associated lymphoproliferative disorder with R-CHOP following administration of rituximab].

: A 65-year-old male had a two-month history of fever and fatigue. He had been receiving low dose MTX administration for about 2 years for rheumatoid arthritis. The blood chemistry findings showed elevated liver function including lactic dehydrogenase (LDH) levels. The quantified serum EBV-DNA level was 200 copies/105 peripheral blood mononuclear cells. Computed tomographic scan demonstrated splenomegaly and intraperitoneal mass lesions. One of the masses was biopsied. Some tumor cells showed a large Hodgkin cell-like appearance. These were CD3e-, CD20 +, CD30 +, CD15-, LMP1 +, EBNA2-, EBER-ISH + without imbalance of the kappa/lambda ratio. A diagnosis of MTX-associated B-lymphoproliferative disorder was made. Although the patient's fever subsided and the serum LDH levels were normalized after withdrawal of the MTX, the masses showed almost no change. Therefore, we administered rituximab weekly for a total of four doses, resulting in normalization of the serum EBV-DNA load and serum CD4/CD8 ratio. The masses persisted, however, so we carried out eight courses of R-CHOP therapy, which induced complete response without any episode of serious infection.