Organizing pneumonia in a patient with rheumatoid arthritis treated with etanercept

Etanercept-induced organizing pneumonia (OP) has not been reported in Japan. We describe the case of a rheumatoid arthritis patient who developed OP during etanercept treatment and discuss the possible mechanisms underlying the development of etanercept-induced OP and the existence of factors that predispose Japanese patients to drug-induced OP.