Recurrence of intracranial meningiomas: the role played by regional multicentricity.

Meningiomas are regarded as benign dural tumors that can be totally removed; however, after a resection that appears to the naked eye to be total, their recurrence rate is high. Malignancy in a few cases and an erroneous belief in many others that the excision was total are among the most accepted explanations. Few studies have mentioned multicentricity as a cause of "relapse." Therefore, the authors decided to examine the dura mater around globular meningiomas for evidence of regional multifocality. A radial strip of dura was removed from the line of attachment of globular meningiomas in 14 consecutive patients. Meningotheliomatous cell aggregates were demonstrated in 100% of these dural strips in the form of either intradural clusters or nodes protruding from the inner aspect of the dura. The benign appearance of the cells and the great prevalence in this study of the benign types of meningioma seem to exclude malignancy; the intradural position of the clusters and their independence from blood vessels apparently negate seeding and dural metastasis. Control strips of convexity dura mater taken from 10 neurosurgical patients without meningioma failed to show these meningotheliomatous conglomerates. These findings indicate that solitary globular meningiomas represent only the most visible growth in the midst of a neoplastic field change spreading over a wide area of dura mater. The authors believe that this can explain some unexpected "recurrences," and that a wide resection of dura around globular meningiomas, whenever possible, could reduce the incidence of clinical growth after true total excision of the most visible lesion. It remains to be determined what factors cause the acceleration of growth of these cell aggregates after removal of the dominant tumor.