ABSTRACT
Purpose This study was to investigate the clinical significance of MDM2 protein expression and gene amplification in atypical lipomatous tumour/well-differentiated liposarcoma (ALT/WDL).Methods MDM2 protein expression and gene amplification were detected by immunohistochemistry of EliVision two-step method and fluorescence in situ hybridization (FISH) in 58 cases of ALT/WDL.Results Immunohistochemical staining showed that the positive rate of MDM2 was 79.3％,MDM2 gene amplification rate by FISH assay was 96.5％.There was statistically significant differences between immunohistochemistry and FISH (P ＜ 0.05).Conclusion MDM2 protein expression and MDM2 gene amplification provide the basis for diagnosis of ALT/WDL.However,a positive rate of MDM2 by immunohistochemistry is nearly 80％,so we recommand to carry out immunohistochemical MDM2 protein detection in most conditions without FISH which can help in the diagnosis of most cases of ALT/WDL.