A case report of phenytoin-induced eosinophilic pneumonia

Eosinophilic pneumonia comprises a rare and potentially serious group of lung diseases characterized by abnormal accumulation of eosinophils in the lungs. Many medications including the anticonvulsant phenytoin, have been implicated in the development of eosinophilic pneumonia. Attributing eosinophilic pneumonia to a medication or toxin can be difficult and may only be achieved by exclusion. The process can be particularly challenging in polypharmacy and when there has been long-term use. Notwithstanding, the presence of a potential offending drug/agent, exclusion of other causes of eosinophilic pneumonia, clinical improvement after cessation of the offending agent, or return of eosinophilic pneumonia after re-challenge are strong indicators for a drug-induced diagnosis. We report a case of phenytoin-induced eosinophilic pneumonia that resolved after medication withdrawal. Considering drug toxicity as a possible etiology of eosinophilic pneumonia is important to allow for the prompt removal of the causative agent, which can result in clinical cure.