middle lobe syndrome, localized atelectasis of the middle lobe of the right lung, characterized by chronic infection, cough, dyspnea, wheezing, and obstructive pneumonitis. Asymptomatic obstruction of the bronchus may occur. The condition arises when the cuff of lymphatic glands that surrounds the middle lobe bronchus becomes enlarged as a result of nonspecific or tuberculous inflammation during childhood. The bronchus is thus compressed, and bronchiectasis develops in the obstructed part of the lung. Treatment includes antituberculosis chemotherapy, administration of corticosteroids, and surgical excision. See also atelectasis, bronchiectasis.
