Primary small bowel mesentery de-differentiated liposarcoma causing torsion with no recurrence for 5 years: A case report and review of the literature.

Rationale: Liposarcoma (LPS) is a rare malignant soft-tissue tumor. Management of LPS is relatively difficult, because there are no characteristic symptoms, or biomarkers, nor any established effective treatment. Hence, the report of the accumulation of each LPS case is necessary. We experienced an extremely rare case of torsion caused by a primary small bowel mesentery LPS.

Patient's Concern: A 70-year-old male consulted our hospital with the complaints of abdominal pain and sudden vomiting.

Diagnosis: No lump could be palpated, and tumor markers tested were within normal limits. However, computed tomography revealed an intestinal obstruction caused by torsion of the small bowel due to an LPS tumor.

Interventions: After decompression of the intestinal obstruction by use of an ileus tube, surgical treatment was performed with rapidity.

Outcome: The torsion was found to be caused by the tumor that originated from the small bowel mesentery. The tumor was resected along with a portion of the small bowel. The growth of adipose tissues of various sizes and containing atypical cells was detected by histopathological examination. Also, immunohistochemical examination resulted in positive immuno-reactions for MDM2, CDK4, and p16INK4, which indicated the tumor to be a de-differentiated LPS. The patient was discharged on postoperative day 14 without any complications, and no recurrence of the tumor was observed at 5 years after the operation.

Lessons: LPS should be considered in differential diagnosis of bowel torsion, and careful management is required because of the high possibility of recurrence. Patients should be followed carefully for at least 5 years, and further accumulation of data will be required in order to establish the appropriate management of LPS.