Liposarcoma are malignant mesenchymal tumours, most often found in the deep muscles of the extremities or the retroperitoneum. The former develop as slow growing masses and the latter are associated with abdominal symptoms. The tumour is found among adults aged forty to seventy years, with myxoid and round cell subptypes occurring in the fifth decade. Moreover, liposarcoma have an equal incidence in males and females.
Liposarcomas which are well differentiated possess a giant ring chromosome, usually involving chromosome 12. Myxoid liposarcomas, on the other hand are characterized by translocations 12:16 and q13;p11, which results in the fusion of the CHOP (encoding a DNA transcription factor) and TLS (encoding an RNA binding protein) genes.
Well differentiated liposarcoma recur around fifty percent of the time, albeit rarely associated with mortatlity. Poor differentiated tumors of the retroperitoneum, however, often recur and metastasize to the lung and the bone; these liposarcoma have a five year survival of twenty percent. Liposarcoma are treated with chemotherapy and radiation therapy.