The angioblastic meningioma: a reappraisal of the nosological problem. Light-, electron-microscopic, tissue, and organ culture observations.

The validity of the concept of the angioblastic meningioma, now in dispute, was reexamined by reviewing 79 meningeal and angioblastic tumors of the central nervous system and by comparing the fine structural characteristics and in vitro evolution of 2 typical meningiomas and 1 intracranial hemangiopericytoma. While most tumors show the consistent features of either hemangiopericytoma or hemangioblastoma, there exist transitional forms between these tumors and typical meningioma. There is also a greater degree of morphological overlap at the electron microscopic level than has been recognized up till now. In view of these findings the concept of the angioblastic meningioma deserves to be retained as a generic term to include craniospinal hemangiopericytomas and transitional forms between hemangiopericytoma, hemangioblastoma and classic meningioma. It is postulated that all these tumors share a common origin from polyblastic mesenchymal cells originating in or derived from the meninges.