Methotrexate pneumonitis after systemic treatment for ectopic pregnancy.

Pneumonitis is an infrequent complication of methotrexate therapy. Described is a case of pneumonitis after treatment of an ectopic pregnancy. A 20-year-old white woman, gravida 3, para 0, ectopic pregnancy 2, was treated for her third ectopic pregnancy with 88 mg (50 mg/m2) of intramuscular methotrexate. Four days later acute dyspnea, tachypnea, fever, patchy infiltrates on chest x-ray films, and a PO2 of 30 mm Hg developed. Respiratory distress resolved over 48 hours. Pneumonitis should be suspected in any patient treated with methotrexate who has unexplained dyspnea.