Significance of MIB-1 staining indices in meningiomas - Comparison of two counting methods

The authors evaluated the predictability of MIB-1 immunohistochemistry for growth and recurrences of meningiomas using two different counting methods: 1) in the area of the highest MLB-1 labeling (HL method) and (2) in random ly selected fields (RS method), The MIB-1 staining indices (SIs) deter mine d by the HL method were approximately twice as high as those by the RS meth od, and the correlation coefficient between them was high (R = 0.86) in 139 meningiomas when transformed logarithmically. The differences in SIs in hi stologic grades were significant with either method. Tumor doubling time (T d) was calculated in 22 meningiomas from serial radiologic examinations. Th e RS method yielded a slightly higher correlation coefficient between log T d and log SI than the HL method. When the authors examined the predictabili ty of recurrence in 112 totally removed meningiomas, the RS method distingu ished the recurrent group more definitively. Several benign meningiomas wit h low SIs by the RS method exhibited focal accumulation of MIB-1-positive c ells. Although they were assigned high MIB-1 values by the HL method, these meningiomas did not recur, and therefore obscured the prognostic importanc e of the MIB-1 value with the HL method. Focal accumulation of MIB-1-positi ve cells in meningiomas is not likely to correlate with their biologic aggr essiveness.