MDM2, CDK4 and p16 IHC came positive proving it to be a dedifferentiated liposarcoma.<h4>Conclusion</h4>We report a curious case of retroperitoneal soft tissue tumour with complex morphology and IHC features diagnosed as dedifferentiated liposarcoma based on MDM2, CDK and p16 positivity. The gene discussed is CDK4; the disease is soft tissue neoplasm.