Retroperitoneal dedifferentiated liposarcoma with colon infiltration: a case report and literature review

Figure 1. Abdominal CT. This image showed flocculent, nodular, and cord-like mixed-density lesions in the right perirenal space. The largest nodule measured approximately 3.3 cm × 2.7 cm with ill-defined borders, causing slight compression of the right kidney, and the solid components of the lesions showed enhancement. Additionally, the right lateral conical fascia and prerenal fascia were thickened, with obvious enhancement of the nodular shadows within them [(A–C), red arrow].

Figure 2. Abdominal MRI: This image showed flocculent, nodular, and cord-like mixed-signal lesions in the right perirenal space. The largest nodule measured approximately 3.0 cm × 2.4 cm with ill-defined borders, causing slight compression of the right kidney, and the solid components of the lesions exhibited enhancement. In addition, the right lateral conical fascia and prerenal fascia were thickened, with clearly enhancing nodular shadows observed within them [(A–C), red arrow].

Figure 3. Pathology. This image showed the tumor cells were spindle-shaped and pleomorphic; In some areas, the stroma was myxoid, which contains a small amount of well-differentiated adipocytic components and heterologous differentiation components [H&E, 100x].

Figure 4. Immunohistochemical staining. Retroperitoneal tumor cells showed positive CD34 expression (A); Retroperitoneal tumor cells showed positive CDK4 expression (B); Retroperitoneal tumor cells showed positive P16 expression (C); The in situ fluorescence hybridization test revealed MDM2 gene amplification (D). Retroperitoneal tumor cells showed positive S100 expression (E); Retroperitoneal tumor cells showed positive SMA expression (F).