Pneumothorax as the initial manifestation of idiopathic hypereosinophilic syndrome.

We report a case of hypereosinophilic syndrome in a 47-year-old man who had acute pneumothorax as the initial presentation. Peripheral blood eosinophil count increased continuously over a period of 1 month and was associated with pulmonary changes and appearance of skin lesions on the right chest wall. Idiopathic hypereosinophilic syndrome was confirmed by bone marrow aspiration biopsy and skin lesion biopsy after exclusion of all possible secondary etiologies. The clinical status and chest radiographs showed marked improvement after treatment with corticosteroids.