Dedifferentiated Liposarcoma of Thigh With Chondrosarcomatous Dedifferentiated Component

Liposarcomas are common soft-issue sarcomas arising predominantly in deep soft tissue and the retroperito­neum with varied mortality and recurrence rates, largely dependent on histologic type. Thought to arise de novo, liposarcomas typically are classified into 5 types based on strict morphologic characteristics: well-differentiated, dedifferentiated, myxoid, round cell, and pleomorphic. More specifically, dedifferentiated liposarcoma, a com­mon type most prevalent in the retroperitoneum, often has 2 distinct components, a well-differentiated lipoma­tous component and a dedifferentiated nonlipomatous component composed of sarcomas, such as myxofibro­sarcomas or other spindle-cell sarcomas. Morphology typically ranges from low- to high-grade components, most commonly exhibiting myxofibrosarcoma and malig­nant fibrous histiocytoma components. However, the case reported in this article is unique—the dedifferentiated component exhibited only chondrosarcomatous differen­tiation—and it is, to our knowledge, the first such case to be described.