Methotrexate-induced pneumonitis in a patient with Crohn's disease

Pulmonary toxicity is a well recognised but infrequent adverse event of treatment with methotrexate. The vast majority of cases have occurred in patients with rheumatoid arthritis; here we present the case of a 44-year old woman with ileo-colonic Crohn's disease who developed methotrexate pneumonitis. The patient had a 10 year history of Crohn's disease and, in the last 18 months, she was treated with oral methotrexate because of steroid-dependency and intolerance to thiopurines. She was admitted to the hospital because of acute dyspnoea, non-productive cough and fever. High-resolution CT scan showed diffuse bilateral areas of ground-glass opacity, and pulmonary function tests disclosed a mild obstructive pattern with a decrease in carbon monoxide diffusing capacity. Blood cultures for pathogenic bacteria or fungi were negative as well as serologic tests against major pneumotropic agents. Methotrexate-induced lung injury was considered: the drug was discontinued and the patient received a steroid course with rapid symptomatic improvement. After 4 weeks pulmonary function tests and high-resolution chest CT scan were normal. To our knowledge this is the second reported case of methotrexate-induced pneumonitis occurring in a patient with Crohn's disease. A definite diagnosis has been made not invasively according to clinical, laboratory and radiological criteria and excluding any infectious aetiology of the pulmonary findings.