Intrathoracic omental herniation mimics posterior mediastinal lipomatous tumor

Intrathoracic omental herniation is an esophageal hiatal hernia that does not involve the stomach and has been previously misdiagnosed as a lipomatous tumor. We report the case of a 72-year-old man who was referred to our hospital for investigation of a chest abnormal shadow. The large mediastinal mass with fat density was not recognized 5 years ago. Although it mimicked a mediastinal lipomatous tumor, we could preoperatively diagnose it as intrathoracic omental herniation. Contrast-enhanced computed tomography was effective in making an accurate diagnosis, showing the mass and vessels passing through the esophageal hiatus from the abdominal cavity. Laparoscopic surgery was performed, and the hiatus was repaired. To diagnose the mediastinal lipidic mass as intrathoracic omental herniation preoperatively can provide less invasive procedure.