Autoimmune hepatitis as an adverse effect of long-term methotrexate therapy.

Methotrexate (MTX) is one of the most commonly used medicines in the treatment of psoriatic arthritis. The drug can produce steatosis and cirrhosis. Autoimmune hepatitis is a rare and serious adverse effect. We describe the case of a 53-year-old woman who developed autoimmune hepatitis after a long-term use of MTX for psoriatic arthritis. Hepatitis was completely resolved 4 months after stopping this drug. The pathophysiologic mechanisms of a drug-induced autoimmunity are unclear and complex. This report confirms the need to monitor liver enzymes carefully in patients using long-term treatment with MTX for psoriasis or rheumatoid arthritis.