ASSESSMENT OF PROLIFERATING-CELL NUCLEAR ANTIGEN IMMUNOSTAINING IN SOFT-TISSUE TUMORS - RELATIONSHIP TO HISTOLOGICAL GRADE AND MITOTIC-ACTIVITY

The proliferative activity in 70 cases of soft-tissue tumours was esti mated immunohistochemically using the monoclonal antibody PC-10, which recognizes proliferating-cell nuclear antigen (PCNA) in paraffin sect ions. The PCNA index (i.e. the percentage of positive neoplastic nucle i) and to a lesser degree the PCNA count (i.e. the number of positive neoplastic nuclei per ten high-power fields) positively correlated wit h the malignancy grade (PCNA index: P<0.001; PCNA count: P<0.01). Howe ver, the range of values of PCNA index and PCNA count was similar betw een benign and grade I tumours. A statistically significant positive c orrelation was also established between PCNA index and PCNA count on t he one hand and mitotic count on the other, but the correlation coeffi cient was low (r=0.351, P<0.01, and r=0.290, P<0.05 respectively). The se results indicate that PCNA immunostaining may successfully be used as an adjunct to the conventional histopathological parameters in asse ssing the malignancy grade in soft-tissue tumours although it is of li mited value in distinguishing between benign and grade I tumours.