Malignant meningioma: ultrastructure and observations on histogenesis

Clinical pathology of malignant meningiomas

Nineteen cases of malignant meningiomas-seven haemangiopericytic, two papillary and ten of the anaplastic type-were examined clinicopathologically. These were ten male and nine female patients and eleven of these received reoperation for recurrence. Tumours of the hemangiopericytic type had similar angiographic and macrooscopic features and malignant characteristics were found microscopically in some tumours. There were intratumoral cysts in both cases of the papillary type and these tumours had a high cellularity, an increased number of mitosis, haemorrhage and partially haemangiopericytic patterns. Six cases of the anaplastic type had changed from a benign type at recurrence and those tumours had variable features radiographically and macroscopically. Lack of typical arrangement, a large number of mitoses, increased cellularity, focal necrosis, brain infiltration, pleomorphism and anaplasia were found histologically. Four cases of the anaplastic type were diagnosed at the first operation and these tumours had apparently similar angiographic and macroscopic features, but with variable organoid structures and malignant forms, microscopically. Electron microscopic features are also described. In malignant meningiomas, the recurrence rate was high even in cases of total removal. The outcome for these patients was good in the papillary type, relatively good in the haemangiopericytic type and poor in the anaplastic type. From these results therapeutic indications are also suggested.

On the pathology of meningiomas. A study of 412 cases

Some pathological features of tumors arising primarily in the meninges are discussed on the basis of 412 surgically treated meningiomas during the period running from 1964 to 1978. Cases of meningeal sarcomas were not considered. Except for a few cases, pathology and clinical course have been generally in agreement. The incidence of histological types like meningotheliomatous, fibroblastic, angioblastic or atypical meningiomas has been verified in relation to sex, age and intracranial or spinal conventional locations. The problem of recurrencies has been studied either comparing the histological features with the first observation or comparing histopathological types with location and details of surgical procedure. Additional criteria like uni or multifocal origin of the tumors and histological features of the peri-lesional tissues, often harbouring small meningiomatous nests, have been taken into account.