MDM2 and undifferentiated (embryonal) sarcoma: We report herein a case initially diagnosed as undifferentiated sarcoma that was reclassified as intraperitoneal dedifferentiated liposarcoma showing an amplification of the murine double minute 2 (MDM2) gene, in order to emphasize that in most cases of undifferentiated sarcomas, a specific line of differentiation can be demonstrated.