Multifocal Giant Retroperitoneal Dedifferentiated Liposarcoma with dual heterologous dedifferentiation– a diagnostic and therapeutic challenge

Dedifferentiated liposarcoma (DDL) with divergent dedifferentiation is uncommonly reported with variable incidences. Liposarcomas, particularly those manifesting dedifferentiation, occur in the retroperitoneum. They grow into large size, present at very late stages, and can have a poor clinical outcome. Here we present a rare case of recurrent dedifferentiated liposarcoma with dual heterologous differentiation with osteosarcoma and Chondrosarcoma in an elderly male who had initially presented with inguinal hernia. A large mass was occupying the entire abdomen, confirmed on CECT occupying the left side with loss of fat planes with the left kidney and spleen. During exploratory laparotomy, a large retroperitoneal mass occupying the whole abdomen from the left side of the retroperitoneum pushing the left and transverse colon with the mesocolon, the ureter to left side across midline was found, which was excised with the kidney preserved. Grossly multiple large fragments of tumor masses were received, ranging in size from 15 to 40 cm in their most significant dimension and weighing more than 25kgs. Extensive sampling from all the tumor masses was done for histopathology, which revealed well-differentiated liposarcoma having juxtaposed heterologous differentiation into chondrosarcomatous and osteosarcomatous areas. A final diagnosis of recurrent multifocal giant retroperitoneal dedifferentiated liposarcoma with dual heterologous differentiation with osteosarcoma and ChondrosarcomaChondrosarcoma was made. Despite recurrent multifocal tumors, the radiological information, extensive excision, detailed grossing, and histopathology helped in the diagnosis.