Multiple meningiomas of different pathological features: case report.

Meningioma is a common intracranial tumour and it may occur not infrequently as one of the multiple tumours, especially in patients with neurofibromatosis. The incidence of multiple meningiomas (MMs) without the stigmata of neurofibromatosis is rare, ranging from 1 to 9% of all meningiomas in the literature. Multiple meningiomas with different pathologic features are even rarer, and most of them are benign histologies. The authors report an extremely rare case of MMs which were presented with malignant and benign histological features simultaneously. The underlying mechanism of MM formation is still unclear, however, subarachnoid spread was thought to be the most likely mechanism. The findings of most of MMs showed identical histopathological features and several molecular biologic studies provided evidence for the monoclonal origin of MMs to back up the above hypothesis. However, different histological features among the reported multiple meningioma cases including our particular one, suggests their origin from multicentric neoplastic foci activated by a supposed tumour-producing factor. However, we cannot completely exclude the possibility of independent progression from monoclonal origin.