摘要A59-year-old man was admitted to our hospital for further examination of an abnormal shadow which appeared on his chest X-ray.A postero-anterior view of his chest X-ray demonstrated a large,sharply defined mass.The mass measured about 10 cm in diameter with a smooth outline (Figure 1A).The patient was asymptomatic,without abnormal physical or laboratory findings.The contrast enhanced CT examination showed that a mass in the inferior posterior mediastinum was located between the heart and thoracic vertebra.No herniation of the stomach or intestines into the thorax was found (Figure 1C).Fine branching linear strands were evident in the mass which was considered to be the branches of the gastroepiploic artery.During the enhanced phase,we could also see gastroepiploic artery passing though the esophageal hiatus (Figure 1D).The density of the mass was about-115 to-120 Hounsfield units,which was in the range of fatty tissue.Our primary diagnosis of the mass was intrathoracic omental hemiation through the esophageal hiatus.