Long-Term Recurrence of Retroperitoneal Dedifferentiated Liposarcoma After a Complete Surgical Resection: A Report of a Rare Phenomenon.

The objective of this report is to present a rare case of a recurrence after 20 years of retroperitoneal dedifferentiated liposarcoma after surgical resection and to discuss the lessons learned from this rare phenomenon for patients management and understanding the behavior of these aggressive tumors.  A 75-year-old woman presented with recurrent retroperitoneal dedifferentiated liposarcoma who had undergone a surgical resection 20 years earlier and had no evidence of disease on frequent follow-ups during that period. The histopathologic examination revealed different morphologic characteristics between the initial and recurrent presentations. The fluorescence in situ hybridization showed amplification of the mouse double minute 2 homolog (MDM2), a regulator of p53 gene on chromosome 12q15, and positive cyclin-dependent kinase 4 (CDK4) immunostain. Liposarcoma long-term recurrence is a challenging surgical disease to provide the best survival outcome. Incomplete resection could explain the recurrence in anatomic locations where the lesions are intermixed with the neighboring adipose tissue. However, dedifferentiated liposarcoma can rarely recur after 20 years. The molecular transformation and the survival analysis of these tumors predict certain behaviors. The refraction for radiation therapy in our case and the mixed morphology provide some insight into the biology and the clinical management for these aggressive tumors.