[A case of diphenylhydantoin-induced pneumonitis].

A 60-year-old man had been administered diphenylhydantoin (DPH) for prevention of convulsive seizures following clipping of an aneurysm of the middle cerebral artery. About one month after the commencement of DPH administration, he developed cough and low grade fever. He was treated with various antibiotics, but his condition increasingly worsened. Chest X-ray film revealed bilateral interstitial processes throughout the entire lung fields. Transbronchial lung biopsy was performed and the obtained specimen showed histological findings compatible with drug-induced pneumonitis. Administration of DPH was stopped immediately and 50 mg/day of prednisolone was started. The patient's condition rapidly improved, and the abnormal shadows on chest X-ray film gradually diminished. The lymphocyte stimulation test by DPH was positive with a stimulation index of 282%.