NITROFURANTOIN‐INDUCED ALTERATIONS IN PULMONARY TISSUE

Three patients with acute and two with subacute nitrofurantoin‐induced pulmonary reactions were studied clinically and by examinining microscopically needle biopsy specimens of their lungs. In all five patients slight vasculitis and a few interstitial eosinophils were found in the pulmonary tissue 1–2 weeks after the withdrawal of nitrofurantoin therapy. Alveolitis, fibrinous alveolar exudate and perivascular granulomas were also seen in some specimens. The patients with acute reactions had marked blood eosinophilia. In all patients, pulmonary diffusing capacity (DL CO ) was below normal, but ventilatory function was not appreciably affected. Withdrawal of nitrofurantoin resulted in complete or partial improvement in 4–8 weeks. Our clinical and histological findings support the suggestion that a type III immune‐complexmediated reaction is involved in acute and subacute hypersensitivity reactions to nitrofurantoin.