[Rapid Recurrence of Dedifferentiated Liposarcoma of Occult Primary in the Abdomen-A Case Report].

A man in his 70s was referred to our hospital for the examination of an abdominal tumor detected incidentally. The tumor was resected with a preoperative diagnosis of gastric submucosal tumor. As a result of the histopathological examination, dedifferentiated liposarcoma was diagnosed. The tumor recurred 2 months after the operation, and resection was attempted again. However, the intraoperative findings showed multiple metastatic lesions, and radical resection was considered impossible. Chemotherapy was therefore administered with doxorubicin monotherapy and eribulin, but the tumor rapidly increased, and the patient ultimately died 8 months after the initial operation. Dedifferentiated liposarcoma is a histologic type with a poor prognosis among liposarcoma. Resection is the standard treatment, but it frequently develops in the retroperitoneum, and it is often found in an advanced state due to the lack of subjective symptoms compared to lesions of the extremities. In addition, its tendency to infiltrate into the surrounding area and to metastasize are also factors that make radical resection difficult. We herein report a case of dedifferentiated liposarcoma that was detected asymptomatically but had a rapid outcome.