Gynecomastia associated with low-dose methotrexate therapy for rheumatoid arthritis.

A 68-year-old man with a 3-year history of rheumatoid arthritis (RA) developed gynecomastia 3 months after beginning oral low-dose methotrexate (MTX) therapy. Four months after MTX therapy was discontinued, the gynecomastia symptoms improved. Only eight cases of gynecomastia resulting from low-dose MTX administration have been reported worldwide, and no cases have previously been reported in Japan. Although it occurs infrequently, gynecomastia resulting from low-dose MTX therapy should be considered in male patients with RA.