Clinicopathological evaluation of immunohistochemical Ki-67 and endothelial nitric oxide synthase expression in intracranial ependymoma.

PURPOSE To analyze the association between Ki-67 and eNOS expression with the pathological grades of patients with intracranial ependymomas, and to determine its value in distinguishing the progression of the disease. METHODS A clinicopathological study was undertaken in 82 patients with intracranial ependymomas. Tissue samples, obtained by tumour resection, were divided into three groups: low-grade, mid-grade and high-grade ependymomas. Tissue samples obtained from 15 patients with brain contusion were used as control. Immuno-histochemical staining was performed to analyze the association between Ki-67 and eNOS expression with various tumour grades. The cell proliferating marker Ki-67 was assessed by positive cell count. The levels of eNOS positive expression were evaluated as slight, moderate and intense. RESULTS 48 of 82 cases (58.54%) expressed Ki-67 protein. Expression of Ki-67 and eNOS was negative in all control samples. Positive cell rates were 2.65+/-0.83 % in the low-grade, 9.63+/-0.08 % in the mid-grade, and 28.41+/-0.71 % in the high-grade ependymoma groups. In low-grade ependymomas there were 8 and 12 cases that expressed eNOS slightly or moderately. In the mid-grade ependymoma group eNOS was expressed moderately in 10 cases and intensely in 15. In the high-grade group 20 cases showed intense positive expression of eNOS. The Ki-67 positive cell counts for slight, moderate and intense eNOS expression were 2.20, 6.07 and 22.25, respectively. CONCLUSION Ki-67 and eNOS expression in intracranial ependymoma tissue was associated with the histopathological grade and malignant degree.