[Pulmonary eosinophilic granuloma presenting as a solitary pulmonary nodule]

A symptomless 60 year old man with a heavy smoking history presented with a nodule in the right lung, which was found by an annual chest X-ray. Chest CT showed a 1 cm speculated nodule in the right S8. Bronchoscopic transbronchial biopsy to the nodule yielded no definite diagnosis. Since the nodule was highly suggestive of lung cancer, wedge resection was performed by video-assisted thoracoscopic surgery. Pathological findings of the specimen showed that the nodule consisted of a mixed population of histiocytoid cells with eosinophils. The nuclei and cytoplasms of the histiocytoid cells were stained positively for S-100 protein. Pulmonary eosinophilic granuloma (PEG) was diagnosed. Common radiographic findings of PEG should present with a mixture of multiple nodular shadows and cystic lesions. PEG presenting as a solitary nodule is rare.