Assessment of proliferative potential of meningiomas using PCNA LI and AgNOR counts

Seventy-six cases of international meningiomas were studied using staining for Proliferating Cell Nuclear Antigen (PCNA) and silver nucleolar organizer regions (AgNORs) in order to find out any correlation of these parameters to the histological typing of the tumours and their biological behaviour. Histologically, 35 of the 76 cases were benign, 12 atypical and 19 malignant. Ten cases were recurrent. A male preponderance with a male: female ratio of 1.6:1 was noted. Five of 76 cases were in children below 15 years of age. Majority of the tumours were convexity meningiomas. Overall PCNA labeling index (LI) values ranged from 0.1% to 11.0%. Benign group had an LI of 0.9 +/- 1.42 whereas atypical, malignant and recurrent group had LIs of 4.06 +/- 2.33, 2.91 +/- 2.66 and 3.36 +/- 3.76 respectively. One way analysis of variance test showed a significant difference in the distribution of LI between benign versus atypical, malignant and recurrent group (P < 0.05). A highly significant difference was also observed between PCNA LI of recurrent benign group versus non-recurrent benign group (p < 0.01, wilcoxon Rank Sum Test). On further classifying the tumours based on LI values, it was observed that 30 of 41 (73%) cases of combined atypical, malignant and recurrent group (i.e. biologically more aggressive group) had LI of > 1%, whereas 26 of 35 cases (74%) belonging to the benign group had LI of < 1%. Overall AgNOR counts ranged from 1.27 to 3.11. No statistically significant difference was found in AgNOR counts amongst the different groups of meningiomas. There was no correlation between PCNA LI and AgNOR counts. It was thus concluded that PCNA LI but not AgNOR counts in the primary tumour could be of potential value for more accurate assessment of biologic behaviour of meningiomas in conjunction with the conventional A histological parameters.