MDM2 and undifferentiated pleomorphic sarcoma: Regarding MDM2, the specificity may be high in cases with differentiating myxoid liposarcoma and pleomorphic liposarcoma because these liposarcomas almost always show negativity (15), although they may be low in cases with differentiating myxofibrosarcoma and undifferentiated pleomorphic sarcoma because these sarcomas occasionally show positivity (13).