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.