RESUMEN
Liposarcoma is the most common primary retroperitoneal sarcoma in adults. We report the case of an 86-year-old male who presented to the emergency department with frequent falls and unexplained weight loss that was found to have a cystic retroperitoneal dedifferentiated liposarcoma. Initial computed tomography revealed a large heterogeneous complex cystic hypoenhancing lesion in the left retroperitoneum. Subsequent magnetic resonance imaging demonstrates a multilocular cystic mass with microscopic lipid content, diffusion restriction, and enhancing nodular soft-tissue components. Histologic examination of the tissue sample following biopsy is consistent with cystic retroperitoneal dedifferentiated liposarcoma. Further management was not pursued due to the patient's advanced age and frailty.