A rare type of cancer that begins in fat cells. It usually occurs in the thigh, but it may also occur in the buttock, back of the abdomen, or trunk (chest and abdomen). Some myxoid liposarcoma cells have a certain genetic change called a translocation (part of one chromosome switches places with part of another chromosome). Myxoid liposarcoma usually occurs in adults, and is rare in children and adolescents. It is a type of soft tissue sarcoma.