A CASE OF RETROPERITONEAL LIPOSARCOMA THAT DEDIFFERENTIATED IN A LONG PERIOD OF TIME

Abstract

Retroperitoneal liposarcoma is a rare tumor, but it is the most common subtype of retroperitoneal tumor accounting for approximately 20% of all retroperitoneal sarcomas. Good prognosis can only be achieved through a complete resection at the initial operation, and its outcome is greatly determined by the histological subtype. We report a case of retroperitoneal liposarcoma that dedifferentiated in a long period of time. A 51-year old woman experienced a total of 9 operations in 16 years, and along the way, the histological subtype changed from a mix of myxoid and well-differentiated type to a dedifferentiated type. Dedifferentiated liposarcoma has a poor prognosis, and our case relapsed 3 months after the operation. Because the recurrent tumor caused ileus, we carried out the operation once again. Even though we tried sequential chemotherapy (high-dose ifosfamide) after the operation, the disease became uncontrollable, and the patient died six weeks after the last operation. As a conclusion, we find it important to pay strict attention to the histological subtype when treating a retroperitoneal liposarcoma.