Pustular psoriasis induced by hydroxychloroquine: a case report and review of the literature.

A variety of pharmacologic agents have been known to induce pustular psoriasis. We describe a patient with a positive personal and family history of psoriasis who developed an extensive annular pustular eruption 3 weeks after starting hydroxychloroquine (Plaquenil) for arthritis. The drug was discontinued, and she received 3 weeks of systemic and topical corticosteroids; in spite of the therapeutic intervention, showers of new lesions appeared daily, and progressed to involve 75% of the body. The development of new lesions stopped, and the older lesions began to clear after one dose of 7.5 mg of methotrexate. Subsequently, methotrexate therapy was stopped because of mild transaminase elevation; the pustular lesions then flared. New lesions stopped appearing after four doses of weekly methotrexate. The patient remains clear of lesions 6 months later.