A usually painless malignant tumor that arises from adipose tissue. Microscopically, it may contain a spectrum of neoplastic adipocytes ranging from lipoblasts to pleomorphic malignant adipocytes. Morphologic variants include: well differentiated, dedifferentiated, pleomorphic, and myxoid liposarcoma. The metastatic potential is higher in less differentiated tumors. The disease is MONDO_0005060 (liposarcoma). Also known as: lip sarcoma, liposarcoma, malignant, sarcoma of lip.