Soft Tissue Tumors

Atypical Lipomatous Tumor/Highly Differentiated Liposarcoma Apply to atypical lipomatous tumour/well-differentiated liposarcoma (ALT/WDL). This tumor often has MDM2 amplification and CDK4 amplification. When a diagnosis of subcutaneous ALT/WDL is to be made, lipomas with similar morphology should first be excluded, such as spindle cell lipoma, pleomorphic lipoma, chondroplastic lipoma, and cell-rich angiomyolipoma, etc. ALT/WDL often has simultaneous amplification of MDM2, and CDK4, which can help in the differentiation. Apply to dedifferentiated liposarcoma (DL) and highly differentiated liposarcoma. Similar to ALT/WDL, shows ring chromosome and giant chromosome, amplification of the 12q13-21 region, and MDM2 amplification in most retroperitoneal dedifferentiated liposarcomas. Differentiated liposarcoma with epithelial/epithelioid cell morphology is easily misdiagnosed as carcinoma or mesothelioma, and MDM2 amplification has a good differential diagnosis. Highly differentiated liposarcoma with MDM2 amplification can be used in the differential diagnosis with lipoma. Rhabdomyosarcoma MDM2 gene amplification is present in 22-56% of rhabdomyosarcomas. Soft Tissue Tumors In bone tumors, MDM2 amplification can be used in the differential diagnosis of highly differentiated osteosarcoma from benign or reactive bone lesions. Differential diagnosis of low-grade osteosarcoma with other primary fibro-osseous lesions.