Feldman Gregory J. M.D.Journal of Bronchology: July 1999 Brief Report: PDF Only Free Abstract Atelectasis of an entire lung usually occurs in association with occlusion of a main bronchus by bronchogenic carcinoma, mucous plugging, and rarely by benign tumor or aspirated foreign body. The mucous plugging in nonintubated patients often occurs in a setting of impairment of ventilatory function, for example, in those with chronic bronchitis during the postoperative period or neuromuscular disorders. This article describes what appears to be a first-reported case of mucoid impaction of the entire main bronchus in a previously healthy patient. A 43-year-old woman presented with atelectasis of the left lung caused by obstruction of the left main bronchus by necrotic mucoid lesion. A correct diagnosis unsuspected initially was established after the lesion was removed using a rigid bronchoscope. A fungal culture showed heavy growth of Cladosporium cladosporioides, a fungus not previously known to precipitate pulmonary disease. © 1999 Lippincott Williams & Wilkins, Inc.