Folded lung: a masquerader of malignancy.

Four cases of folded lung were observed over an 8-year period up to 1990. Because of suspected malignancy, three patients underwent exploratory thoracotomy, without subsequent morbidity or mortality, but the fourth patient declined surgery. Although folded lung may have characteristic computed tomographic features, these may be mimicked by carcinoma. If the patient is fit enough, exploratory thoracotomy is advisable in order to establish the diagnosis and permit resection of the lesion, if indicated, while avoiding the risks entailed by false negative CT scan and needle biopsy.