Nocardia asteroides pneumonia complicating low dose methotrexate treatment of refractory rheumatoid arthritis.

Low dose methotrexate is used increasingly often in the treatment of rheumatoid arthritis. Severe complications due to toxicity of the lung or bone marrow occur infrequently. This report describes a 71 year old woman with longstanding rheumatoid arthritis who developed pleuritis, a pulmonary infiltrate, and pancytopenia during treatment with low dose methotrexate. Fatal respiratory insufficiency followed, and cultures from the lung after death showed Nocardia asteroides.