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 aggressively. In order to characterize factors that may influence this behavior, we chose to compare MIB-1 labeling index (LI) and telomerase RNA localization (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 hTR is detected in many neoplastic cells, and may play an essential role in cell immortalization. The study group consisted of five papillary meningiomas (and a recurrence in one case), 11 conventional meningiomas, and eight atypical meningiomas. Conventional meningiomas showed either negative or 1+ hTR. Atypical meningiomas showed 1+ hTR. Papillary meningiomas showed the highest 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% for papillary meningiomas. LI differentiated between meningiomas, and papillary 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 with papillary meningioma.