A rare well-differentiated renal retroperitoneal liposarcoma: a case report.

Introduction and importance: Retroperitoneal liposarcomas (RPLPSs) are rare tumors that arise from mesenchymal cells in the peritoneum cavity. The sites of PRLPSs vary a lot, but renal PRLPSs are extremely rare (there are only 45 cases of Renal retroperitoneal liposarcomas on PubMed). In this case, the authors present a rare renal retroperitoneal liposarcoma case, describe the major concepts, and raise awareness about this rare tumor. Case presentation: A 44-year-old woman presented to the clinic with hirsutism and irregular menstruation; upon physical examination, a large abdominal mass was accidentally identified; the patient had Doppler ultrasound (Doppler US) and MRI, which both showed a mass arising from the right upper pole of the kidney, fine needle aspiration (FNA) confirmed the diagnosis of retroperitoneal liposarcoma, patient underwent surgical removal and her symptoms disappeared. Clinical discussion: The retroperitoneum is a cavity behind the abdominal wall containing organs like the pancreas and kidneys. Retroperitoneal tumors (RPTs) are rare neoplasms, primarily of mesenchymal origin. Retroperitoneal liposarcomas (RPLPS) are the most common RPT, often asymptomatic until large, and rarely metastasize but frequently recur. Liposarcomas are classified into five subtypes, with well-differentiated liposarcoma being the most common and characterized by high local recurrence. The presence of specific oncologic mutations affects the prognosis and the response to treatment. Conclusion: In rare cases, retroperitoneal liposarcomas can arise from sites near the kidney and compress the adjoining adrenal gland.