Acquired segmental emphysema: the enlarging spectrum of Swyer-James/Macleod's syndrome.

Three cases of Macleod's syndrome are described, all of which required surgical resections for distressing symptoms. This provided a rare opportunity to examine the pathologic features of a condition that is usually diagnosed on its radiologic features, and the etiology of which remains unestablished. Three patients (2 women and 1 man), aged 20, 23, and 24 years, were referred from respiratory physicians because of unilateral hyperlucent lungs and associated symptoms. All 3 patients had unilateral hyperlucent lungs, but only 1 patient had demonstrable mediastinal shift on expiratory and inspiratory chest computed tomographic scan. Segmentectomies were performed (n = 4) in all the patients without perioperative morbidity or mortality. Patients have been followed up between 6 and 18 months, and remain asymptomatic with a return to normal lifestyle. Histologic examination of the specimens found inflammation of the bronchus in all 3 patients, but only two specimens had evidence of bronchiolar inflammation. In only 1 patient was there a reduction in bronchiole number. All 3 patients showed presence of emphysema. These cases are notable for the segmental distribution of the disease. Pathologic examination lends support to the theory that previous respiratory tract infection may play a role in the pathogenesis of this condition.