A 70-year-old male presented with sudden abdominal pain and vomiting, diagnosed with small bowel torsion caused by a primary small bowel mesentery de-differentiated liposarcoma (DDLPS). Computed tomography (CT) revealed intestinal obstruction and a low-density mass. After decompression with an ileus tube, surgery was performed, revealing the tumor in the mesentery. Histopathological and immunohistochemical examination confirmed DDLPS. The patient was discharged on postoperative day 14 with no complications and no recurrence at 5 years. Liposarcoma (LPS) is a rare malignant soft-tissue tumor with no specific symptoms or biomarkers. DDLPS is a subtype of LPS, often associated with recurrence or metastasis. This case highlights the rarity of DDLPS causing bowel torsion. The tumor was resected, and the patient had no recurrence without adjuvant chemotherapy. DDLPS is diagnosed using immunohistochemical markers such as MDM2, CDK4, and p16INK4. The case shows that DDLPS can arise from the small bowel mesentery and cause torsion. Complete surgical resection is the primary treatment, but adjuvant chemotherapy and radiotherapy are debated due to potential complications. This case emphasizes the importance of considering LPS in the differential diagnosis of bowel torsion. Long-term follow-up is necessary, as recurrence is possible. Further research is needed to establish optimal management strategies for LPS. The case also highlights the rarity of DDLPS causing bowel torsion, with only a few reported cases in the literature. The patient's 5-year follow-up with no recurrence suggests that complete resection may be sufficient in some cases.A 70-year-old male presented with sudden abdominal pain and vomiting, diagnosed with small bowel torsion caused by a primary small bowel mesentery de-differentiated liposarcoma (DDLPS). Computed tomography (CT) revealed intestinal obstruction and a low-density mass. After decompression with an ileus tube, surgery was performed, revealing the tumor in the mesentery. Histopathological and immunohistochemical examination confirmed DDLPS. The patient was discharged on postoperative day 14 with no complications and no recurrence at 5 years. Liposarcoma (LPS) is a rare malignant soft-tissue tumor with no specific symptoms or biomarkers. DDLPS is a subtype of LPS, often associated with recurrence or metastasis. This case highlights the rarity of DDLPS causing bowel torsion. The tumor was resected, and the patient had no recurrence without adjuvant chemotherapy. DDLPS is diagnosed using immunohistochemical markers such as MDM2, CDK4, and p16INK4. The case shows that DDLPS can arise from the small bowel mesentery and cause torsion. Complete surgical resection is the primary treatment, but adjuvant chemotherapy and radiotherapy are debated due to potential complications. This case emphasizes the importance of considering LPS in the differential diagnosis of bowel torsion. Long-term follow-up is necessary, as recurrence is possible. Further research is needed to establish optimal management strategies for LPS. The case also highlights the rarity of DDLPS causing bowel torsion, with only a few reported cases in the literature. The patient's 5-year follow-up with no recurrence suggests that complete resection may be sufficient in some cases.