RESUMEN

Liposarcoma is a rare soft-tissue neoplasm originating from adipocytes. The exact cause of liposarcoma is unknown and symptoms vary depending on the tumor's location. A 49-year-old man presented to the emergency room complaining of epigastric pain radiating to the back and right upper quadrant. Cross-sectional imaging revealed a large upper abdominal mass that was thought to be a gastrointestinal stromal tumor (GIST) arising from the duodenum at first. The patient underwent en-bloc resection of the mass and was planned for adjuvant chemotherapy. Subsequently, multiple tissue samples were examined, leading to the final diagnosis of de-differentiated liposarcoma. The patient eventually developed multiple recurrences and was subjected to re-resection surgeries and three different chemotherapy regimens. Given the rarity of the disease, no standardized therapy plan is available, highlighting the need for more case reports/series and trials to broaden our understanding of this disease.