A 6-year-old, spayed female domestic shorthair cat was referred for an intermittent cough and wheezing of 3 to 4 months' duration. Thoracic radiography revealed atelectasis of the right middle and caudal lung lobes with hyperinflation of the accessory lobe, consistent with bronchial obstruction. Bronchoscopy confirmed a narrowing of the right mainstem bronchial lumen; however, positive-pressure ventilation resulted in a severe pneumothorax. A lateral thoracotomy and right caudal lung lobectomy resulted in complete resolution of the pneumothorax and respiratory signs. Histopathology and culture of the lung revealed Paecilomyces lilacinus. The cat was placed on itraconazole therapy for 6 months. Since dismissal from the hospital, the cat has not exhibited clinical evidence of wheezing, coughing, or dyspnea and is neurologically normal.