Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 11 1 2025 01 01 122 125 Hassan Tavakoli Department of Surgery, Amir A’lam Hospital, Tehran University of Medical Sciences, Tehran, Iran. Hadi Ahmadi Amoli Department of General Surgery, School of Medicine, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran. Seyed Amir Miratashi Yazdi Department of General Surgery, School of Medicine, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Sharifi Department of General Surgery, School of Medicine, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran. Mina Abdolahi Department of Clinical Nutrition, Amir A’lam Hospital, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Gholizadeh Department of Clinical Nutrition, Faculty of Nutrition and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2024 04 28 2024 05 26 Liposarcoma, a malignant tumor originating from fat cells, is a rare occurrence in the retroperitoneal region. Surgical resection is the standard method for treating this cancer. This type of tumor is classified into common subtypes, which include well-differentiated liposarcoma and dedifferentiated liposarcoma. A 53-year-old male patient presented with lower left quadrant (LLQ) pain and melena for two weeks. Further diagnostic evaluation, including colonoscopy, revealed a 50 mm polyp in the hepatic flexure or distal of the ascending colon. The pathological assessment of the mass demonstrated a lipomatous lesion with a nuclear atypical lipomatous tumor, which was diagnosed as well-differentiated liposarcoma. The patient underwent surgical treatment and was discharged following his recovery. Liposarcoma, a malignant tumor originating from fat cells, is a rare occurrence in the retroperitoneal region. Surgical resection is the standard method for treating this cancer. This type of tumor is classified into common subtypes, which include well-differentiated liposarcoma and dedifferentiated liposarcoma. A 53-year-old male patient presented with lower left quadrant (LLQ) pain and melena for two weeks. Further diagnostic evaluation, including colonoscopy, revealed a 50 mm polyp in the hepatic flexure or distal of the ascending colon. The pathological assessment of the mass demonstrated a lipomatous lesion with a nuclear atypical lipomatous tumor, which was diagnosed as well-differentiated liposarcoma. The patient underwent surgical treatment and was discharged following his recovery. https://aacc.tums.ac.ir/index.php/aacc/article/view/998