Abstract
A 67-year-old man with complaints of fever, abdominal pain, and abdominal distension was admitted to the department of internal medicine at our hospital. An abdominal contrast computed tomography scan showed a tumor, accompanied by an internal heterogeneous contrast effect, in contact with the transverse colon. Surgery was proposed to the patient, and a laparoscopic omental tumor resection was planned for a suspected omental malignant tumor. Initially, surgery started via the laparoscopic approach ; however, a giant tumor was found in the omentum. Consequently, the laparotomy approach was required because the visual field was difficult to secure with a postural change. Although marked venous dilatation around the tumor was observed, there was no invasion to other organs, and omental tumor resection was performed. The pathological diagnosis was an undifferentiated pleomorphic sarcoma (UPS) of the omental primary. UPS of the omental primary is extremely rare, preoperative diagnosis is difficult, and prognosis is poor. Complete resection was performed with no invasion to other organs or distant metastasis noted, and long-term survival is possible. Careful follow-up is required, and the patient may need to consider further surgical resection if a relapse occurs.
