Prognostic factors in anterior skull base meningiomas

Histopathological and immunohistochemical study of prognostic factors in anterior skull base meningiomas in order to determine the post-operative management.

The studied material consisted in resection specimens from 65 patients with anterior skull base meningiomas hospitalized in Clinic of Neurosurgery, National Institute of Neurology and Neurovascular Diseases, Bucharest, Romania, and diagnosed in the Department of Pathology of the same Institute, between 2007 and 2013. The biological material was processed by standard histological technique with Hematoxylin and Eosin staining which allowed the classification of tumors according to WHO 2007 system and the assessment of the morphological parameters of known prognostic value. Subsequently, the tumor fragments were submitted to immunohistochemistry to evaluate the proliferative activity (Ki-67 labeling index) and progesterone hormone receptor (PR) status.

83.07% of the 65 anterior skull base meningiomas were WHO grade I tumors; the grade II tumors accounted 15.38%, while the grade III tumors were rare (1.53%). Mitotic activity was variable, reaching up to 14 mitoses/10 HPF (high-power field) in atypical and anaplastic tumors; mitoses were absent in 64.81% of grade I tumors; the average mitotic index in grade II tumors was 5.15 mitoses/10 HPF. Both mitotic activity and infiltrative and invasive tumor growth (the latter found in 36.92% of cases) were correlated with tumor grade. Ki-67 labeling index ranged between 1.1% and 7.7%, with the highest value found in anaplastic tumor; progesterone receptors (PR) were expressed with variable index in 84.61% of cases. The immunonegative PR tumors were represented by 16.66% of grade I tumors and by the only grade III tumor. In contrast to PR, Ki-67 expression was statistically correlated with tumor grade. The comparison between the expression of Ki-67 and PR revealed an inverse relationship between the level of PR expression and the proliferative activity intensity.

We found that PR expression decreases as the biological behavior of tumor becomes more aggressive; it may be related with an increased risk of recurrence, making the postoperative surveillance more rigorous in these patients.