[Severe acute pneumopathy following low-dose methotrexate therapy in chronic polyarthritis].

A 70-year-old patient with a history of rheumatoid arthritis was hospitalized for severe acute pneumonitis after 36 weeks of treatment with low-dose methotrexate (7.5 mg/week). High dose corticotherapy and assisted ventilation were necessary to obtain a clinical response. Medical history, clinical signs, laboratory findings. X-ray films of the chest and special investigations suggest the diagnosis of acute low-dose methotrexate pneumonitis.