Adult T-cell Leukemia/Lymphoma as a Methotrexate-associated Lymphoproliferative Disorder in a Patient with Rheumatoid Arthritis

The patient was a 74-year-old Japanese woman with rheumatoid arthritis (RA) who developed generalized lymphadenopathy with elevated levels of lactase dehydrogenase (LD), and soluble IL-2 receptor (sIL-2R). She was found to be positive for anti-human T-cell leukemia virus type 1 (HTLV-1) antibodies. Her symptoms and laboratory abnormalities spontaneously regressed after the cessation of methotrexate (MTX), suggesting that she had an MTX-associated lymphoproliferative disorder; however, her lymphadenopathy appeared again approximately 14 months later with LD and sIL-2R elevation. A histopathologieal analysis and Southern blotting of a lymph node biopsy specimen for HTLV-1 provirus supported the diagnosis of adult T-cell leukemia/lymphoma (ATL) (lymphoma type). These data confirmed that an HTLV-1 positive RA patient may develop ATL.