Intracranial osteolytic malignant meningiomas appearing as extracranial soft-tissue masses.

Malignancy is rare in intracranial meningiomas. Although the topic is widely discussed, there is little agreement in the literature as to the histological and radiological features that warrant the diagnosis of malignant meningioma. Three patients are described who had soft-tissue masses and underlying osteolytic lesions on computed tomography. All three patients also had a large intracranial component that proved to be a malignant meningioma. Rarely do meningiomas have all three of these features. We propose that a meningioma causing osteolysis and soft-tissue extension should be considered malignant until proven otherwise.