2008 Volume 22 Issue 5 Pages 818-822
A 26-year-old man with right pneumothorax was admitted to our hospital. Chest X-ray and chest CT revealed a mass arising from the fourth rib. During thoracoscopic surgery, we found a mushroom-like mass and bulla adjacent to the scar of the right middle lobe caused by the mass. We resected the mass and part of the right middle lobe. Pathological findings of the mass proved osteochondroma. The postoperative course was uneventful. Pneumothorax caused by costal osteochondroma is rare.