The role of gallium-67-citrate in the detection of phenytoin-induced pneumonitis.

A patient with a history of cardiac transplant presented with a fever of undetermined etiology. The patient had been on multiple medications, including phenytoin, which can occasionally cause allergic or hypersensitivity pneumonitis. A chest x-ray and CT scan of the chest revealed no active disease. A 67Ga study was obtained after intravenous administration of 377.4 MBq (10.2 mCi) of 67Ga-citrate. The images showed diffuse intense lung uptake bilaterally. Bronchoscopic biopsy revealed hypersensitivity pneumonitis. Phenytoin was withdrawn and corticosteroid was started in therapeutic doses. A follow-up gallium study obtained 25 days after the baseline demonstrated marked improvement in the lungs with concurrent clinical recovery. This case illustrates the usefulness of 67Ga in the detection of drug-induced pneumonitis and in the follow-up of response to therapy.