MDM2 and spindle cell neoplasm: For example, of 201 spindle cell tumors studied by Kashima et al., 7 had MDM2 amplification (3 spindle cell sarcomas NOS, 2 osteosarcomas, and 2 myxofibrosarcomas), of which all were retroperitoneal or intra-abdominal, with some on subsequent review showing WDL components, and these were all reclassified as DDL [41].