A case of retroperitoneal dedifferentiated liposarcoma.

We report a case of retroperitoneal dedifferentiated liposarcoma (DDLPS) confirmed by histopathology and molecular testing. A 66-year-old woman presented with an incidentally discovered left abdominal mass. Contrast-enhanced CT showed multiple adjacent soft-tissue masses in the retroperitoneum; some lesions contained minimal fat density and demonstrated irregular ring-shaped and nodular calcifications. On postcontrast imaging, the tumors exhibited a ``slow-in, slow-out'' centripetal enhancement pattern. Postoperative immunohistochemistry revealed co-expression of MDM2 and CDK4, confirming the diagnosis. A follow-up contrast-enhanced CT scan obtained 9 months after surgery showed local recurrence, and the patient is currently receiving further treatment. This case underscores the importance of considering DDLPS in retroperitoneal masses that show minimal fat content, irregular calcifications, and characteristic enhancement dynamics; confirmatory MDM2/CDK4 molecular testing is essential for an accurate diagnosis.