A 35-year-old woman came to an outside hospital 37 weeks' pregnant and reporting shortness of breath. A chest radiograph performed in the emergency department revealed a right pneumothorax. A 12F catheter was placed to drain the pneumothorax. Subsequently, a persistent air leak developed, and the patient was transferred to the obstetric service at our hospital. Three days after admission, she had an uncomplicated vaginal delivery. However, she continued to have a persistent air leak from her chest tube. Several days later, the air leak ceased but a recurrent pneumothorax developed. This required the placement of a larger chest tube, which once again revealed a persistent air leak.The only significant procedures in the patient's surgical history were a cesarean section and a cholecystectomy. She had a 10 pack-year smoking history and no history of a previous pneumothorax. After the air leak was tracked for 1 week after delivery, the patient was taken for a video-assisted thoracoscopy. A video-assisted thoracoscopic resection of a right lower lobe bleb and mechanical pleurodesis were performed. The patient tolerated the procedure well and was discharged to home on the fourth postoperative day after her chest tube was removed. The case is being presented because of interesting findings in the resected specimen.Dr Patterson: She had had no imaging other than just a chest radiograph? Dr Force: She had a computed tomographic (CT) scan as well. Dr Gierada: On the chest radiograph taken when she was transferred here, you can faintly see the pneumothorax catheter, and there was still a very small right apical pneumothorax. A follow-up radiograph 3 days later showed almost a complete collapse of her right lung (Figure 1). The following day, the lung had come up partly in the morning, and a few hours later it was up almost completely. No obvious lesions were seen in the lungs on images obtained without a pneumothorax present. A CT scan obtained later that same day showed the pneumothorax, and in the right lung base there was a cystic lesion with what looked like perhaps some thin septations with a little thickening of the septations or some vessels running along them. A very thin-walled inferior portion was adhered to it, so that it looked like a thin bleb (Figure 2). This is an unusual location for a bleb as a cause of spontaneous