MIB-1 immunolabeling: a valuable marker in prediction of benign recurring meningiomas.

Histological analysis has limited value to predict biological behavior of meningiomas. We investigated the utility of cell proliferative indicator in the evaluation of histologically benign meningiomas. We selected 25 benign non-recurrent meningiomas, 15 benign recurrent meningiomas after complete surgical resection, 30 atypical meningiomas, and 15 anaplastic meningiomas out of 384 cases studied. MIB-1 Labeling Index was evaluated by two methods: Highest Labeling Index (HLI) and Random Labeling Index (RLI). There was no dependable histological parameter to predict recurrence among benign-looking meningiomas. HLI had significant difference when compared with RLI in all categories. The mean MIB-1 HLI values +/- SD were 3.47 +/- 2.0% for benign meningiomas, 5.08 +/- 4.0% for atypical meningiomas and 11.66 +/- 7.06% for anaplastic meningiomas. In comparison, the mean MIB-1 HLI of benign non-recurrent meningiomas were 2.66 +/- 1.7% and with recurrence were 4.21 +/- 2.78% (P = 0.0339). Using receiver operating characteristic, it was seen that neoplasm recurred with the MIB-1 HLI of > 2.6 having the sensitivity of 64.6% and specificity of 68% among benign (grade I) meningiomas. MIB-1 positive tumor cells were maximally aggregated at the periphery of excised specimen. MIB-1 HLI, integrated with standard histopathology can provide better information about the disease biological nature in benign meningiomas.