A patient with a history of asthma underwent computed tomography (CT). With a soft tissue window (width 330, level 30) the scan of the neck did not show any lesion within the airway lumen, but with a lung parenchymal window(width 1300, level -500), we were able to find a low attenuationg endotracheal mass lesion measuring -320HU. A bronchoscopy was performed and a polypoid mass approximately 2cm in diameter was found within the tracheal lumen. An endoscpic biopsy was not performed due to the risk of bleeding and the bronchoscopy was inconclusive for tissue diagnosis. CT, however, provided a definitive diagnosis by demonstrating fat within the tumor on the lung window.