Retroperitoneal Liposarcoma With Leiomyosarcomatous Differentiation

Abstract

We herein describe a 60-year-old Japanese man with a giant retroperitoneal liposarcoma undergoing leiomyosarcomatous differentiation. He was admitted to our hospital because of a 5-month history of dysphagia and abdominal distention. Abdominal computed tomography showed a giant tumor that occupied the entire retroperitoneal space. The majority of the mass was lipomatous and low density; both a heterogenous and solid mass were also present. A giant retroperitoneal liposarcoma was diagnosed, and tumor resection was performed. At surgery, the tumor was mostly isolated from the retroperitoneum and other organs. Histopathologically, the tumor comprised welldifferentiated and dedifferentiated liposarcoma with heterologous differentiation of the leiomyosarcomatous components, which is a rare phenomenon in liposarcoma. The patient was alive 3 years after the first treatment, although he has had 3 local recurrences (approximately one recurrence yearly) and has been treated by repeated resection and radiotherapy.

Dedifferentiated Liposarcoma of Retroperitoneum With Extensive Osteosarcomatous Component

“…1 According to the most recent World Health Organization (WHO) classification, DDLS is one of the 5 subtypes of liposarcoma 2 and it is composed of 2 distinct components: a WDLS and a nonlipogenic sarcoma. In 90% of cases the dedifferentiated component is represented by a high-grade undifferentiated pleomorphic sarcoma, while only rarely a rhabdomyosarcomatous, leiomyosarcomatous 3 or an osteosarcomatous component can be encountered. Notably, in our case a retroperitoneal WDLS contained an unusual, large (about half of the entire tumor volume) high-grade osteosarcoma as dedifferentiated component.…”