Prognostic value of proliferation index and expression of the RNA component of human telomerase (hTR) in papillary meningiomas

Papillary meningioma is a rare subtype of meningioma that often behaves agg ressively. In order to characterize factors that may influence this behavio r, we chose to compare MIB-1 labeling index (LI) and telomerase RNA localiz ation (hTR) in papillary meningiomas, meningiomas, and atypical meningiomas . LI is now often used to supplement histologic grade in the evaluation of these lesions. More recent studies indicate that increased expression of hT R is detected in many neoplastic cells, and may play an essential role in c ell immortalization. The study group consisted of five papillary meningioma s (and a recurrence in one case), 11 conventional meningiomas, and eight at ypical meningiomas. Conventional meningiomas showed either negative or 1+ h TR. Atypical meningiomas showed 1+ hTR. Papillary meningiomas showed the hi ghest hTR (five of six, including recurrence, 2-3+ and one 1+). Generally, the LI was very low for conventional meningiomas (< 2%). The LI of atypical meningiomas ranged from 3-19%, mean 12%, and from 5.5-17.5%, mean 11.75% f or papillary meningiomas. LI differentiated between meningiomas, and papill ary or atypical meningiomas. hTR further delineated papillary (moderate to high) from atypical meningiomas (low). The combined variable of LI and hTR expression could be a useful independent prognostic indicator in patients w ith papillary meningioma.