The Expression Ki-67 and p53 Protein in Intraabdominal Liposarcomas

ABSTRACT

PURPOSE: The formation of a liposarcoma is Known to be associated with a mutation of the p53 and MDM2 genes, and the histopathological subtypes of a liposarcoma are related to the prognosis of the patient. This study was performd to examine the relationship between the histopathological subtypes, the type of p53 mutation, and the proliferative rate. METHODS: Immunohistochemistry was used to measure the p53 protein and Ki-67 (Mib-1 labeling index) expression levels in 24 liposarcomas cases in which the liposarcoma developed primarily in the abdominal cavity. RESULTS: p53 expression was observed in 11.1% of the well- differentiated liposarcoma cases, 27.3% of the myxoid and round cell liposarcoma cases, and 50% of the pleomorphic liposarcoma cases. There were significant differences between the Ki-67 expression level according to the histopathological subtypes. There were significant differences between p53 positive or negative group and the Ki-67 expression level, and there was a quantitative correlation between them. CONCLUSION: The p53 protein was expressed in 25% of all liposarcomas, particularly in pleomorphic liposarcomas because it was expressed more frequently than in the other liposarcoma subtypes (in 2 cases out of 4 cases). The survival rate was much higher in the mucinous round cell liposarcomas which had high p53 and Ki-67 expression levels. The p53 expression level might be a prognostic predictor of a liposarcoma.