Metastatic meningioma. Hemangiopericytoma or angioblastic meningioma?

The question of whether meningeal hemangiopericytoma is a variant of meningioma ("angioblastic meningioma") or a nosologically distinct entity remains controversial. We present the case histories of an intracranial meningioma and of a meningeal hemangiopericytoma, both of which developed extracranial metastases. The metastatic lesions in both cases were studied by electron microscopy, which demonstrated pericytomatous differentiation in one instance and meningothelial differentiation in the other. This report supports the opinion that meningeal hemangiopericytomas and meningiomas of the CNS are distinct pathological entities.