Abstract
A case of pancytopenia induced by low dose methotrexate (MTX) therapy for rheumatoid arthritis was reported. Thirty-nine years old woman admitted to our hospital because of reiterate fever and polyarthralgia. She had taken prednisolone (PSL) because of fever, morning stiffness and polyarthralgia, with a possible diagnosis of adult onset Still's disease, for 7 years. On admission she was diagnosed as rheumatoid arthritis, because of morning stiffness and proliferating synovitis, with complication of secondary amyloidosis, renal dysfunction and hypoalbuminemia. Low dose MTX therapy (5mg/week) was begun with a partial response. However, stomatitis and pancytopenia occurred 6 weeks later, and rapidly progressed. MTX was discontinued, and she was successfully treated by leucovorin and G-CSF.
Low dose MTX therapy has been reported to be effective for rheumatoid arthritis and severe side effect is rare. She was positive for drug-lymphocyte stimulation test to MTX (SI=441%) and it was speculated that lymphocyte-mediated cytotoxicity in addition to its direct toxicity might be responsible for pancytopenia in this case.
