Methotrexate-induced Pneumonitis: Appearance Four Weeks after Discontinuation of Treatment

A 71-year-old man with a long-standing history of rheumatoid arthritis required methotrexate treatment since 1986, with a total dose of 210 mg. In April 1987, before arthroplastic surgery, methotrexate was discontinued. Four weeks later a syndrome of fever, dry cough, shortness of breath, and diffuse air-space consolidations on the chest radiograph evolved. An antibiotic therapy had no beneficial effect, and a bronchoscopy yielded no pathogens. An open lung biopsy led to the diagnosis of methotrexate-induced pneumonitis. This is the first report of a case where methotrexate-induced pneumonitis developed several weeks after cessation of the treatment. Methotrexate can cause four types of pulmonary adverse reactions: pneumonitis, pulmonary edema, pulmonary fibrosis, and pleuritis. Possible pathogenetic mechanisms, symptoms, treatment, and prognosis are discussed.