[Morphology and clinical significance of the meningeal hemangiopericytoma (author's transl)].

Hemangiopericytomas of the meninges are rare tumors. Three tumors of this type with a course over more than 10 years each are reported. All three tumors were primary diagnosed as meningiomas (one: vascular, two angioblastic). The diagnosis was changed to hemangiopericytoma only then when recurrences and extracranial metastases had occurred. Morphologically, "angioblastic meningioma" and "hemangiopericytoma of the meninges" show striking common features. The principal pattern bases on the blastomatous increase of capillary blood vessels lined by a normal endothelium, extracapillary proliferation of pericyte-like mesenchymal cells and an intercellular network of reticulin fibres. Light- and electron microsopic findings do not demonstrate the characteristics of a meningioma. Furthermore, clinical data and growth pattern of "angioblastic meningioma" and "hemangiopericytoma of the meninges" are well comparable. Therefore, it seems to be justified to interpret these tumors as a tumor entity with identical histogenesis. It is well known that hemangiopericytomas frequently recur and metastasise. On the other hand, meningiomas are usually benign. For those reasons we suggest that these tumors should be uniformly classified as "hemangiopericytoma of the meninges" in order to stress the significance of these particular tumors of the meninges regarding their treatment and behaviour.