Retroperitoneal dedifferentiated liposarcoma with a compressed invasion-free kidney: A rare case report

A 68-year-old female patient presented an evident drop in weight within half a year. A heterogeneous huge tumor was found in the left retroperitoneal space through a nonenhanced abdominal computed tomography. The tumor contributed mass effect on adjacent organs and structures, with equivocal left kidney outline. Enhanced kidney magnetic resonance imaging illustrated its hyper-vascular content and clear border. Radical excision was performed through an open approach. The mass was 25 cm in length and weighed about 5 kg. Grossly, it was accompanied by a compressed but invasion-free kidney. The diagnosis of dedifferentiated liposarcoma was made, and a focally involved margin was identified. The average annual incidence of retroperitoneal sarcomas is 2.7 cases/million. Retroperitoneal soft-tissue sarcoma seldom induces symptoms until the tumor makes a mass effect on adjacent organs. The tumor of this patient stands out as the compressed, yet invasion-free left kidney. Surgical resection is regarded as the only potential curative therapy. Due to the large size at presentation and wide extent of the tumor, it often results in limited resectability or positive margin. Important prognostic factors of retroperitoneal sarcoma involve surgical margin, tumor grade, differentiation, and histologic subtype. Dedifferentiated liposarcoma has a worse prognosis and a positive gross margin implies a higher chance of local recurrence as well as a higher mortality rate.