Idiopathic hypereosinophilic syndrome-related pulmonary involvement diagnosed by bronchoalveolar lavage.

Patients with HES and pulmonary infiltrates may pose certain diagnostic problems as the infiltrates may be attributed to infection, infarction, congestive heart failure, or HES itself. We report an 87-year-old woman with idiopathic HES presenting with bibasal alveolar infiltrates. Differential cell count in BAL fluid yielded a very high percentage (73 percent) of eosinophils. Other authors previously mentioned the absence of eosinophils in the lavage fluid despite an important peripheral eosinophilia in a patient with the idiopathic HES but without HES-related pulmonary involvement. Thus, BAL fluid eosinophilia may suggest HES-related pulmonary involvement. Therefore, BAL might be an important diagnostic tool in the management of pulmonary infiltrates in idiopathic HES.