Introduction: Dedifferentiated liposarcoma (DDLPS) is a rare mesenchymal neoplasm that accounts for approximately 20% of soft tissue sarcomas in the human body. This case report emphasises a high-grade DDLPS with a retroperitoneal location and its unexpected recurrence in a 72-year-old male patient more than 10 years after the primary tumour. This case is particularly significant because of the anomalous presentation of the tumour recurrence time that is complemented by the unusual histologic features of the initial neoplasm, which raises new questions about the biological behaviour of the disease, the clinical course and the management of this pathology.

Expected results: The report seeks to highlight the important and unusual aspects of the pathology that can contribute to a better understanding of its evolution, allowing informed clinical decisions to improve the patient’s quality of life and prognosis.