Primary ectopic meningioma of the neck: MR features.

Although meningiomas represent 15% of the tumors of the CNS, primary ectopic meningioma is a very rare finding. Four mechanisms for the formation of ectopic meningioma have been suggested: (a) direct extension of an intracranial lesion; (b) distant metastasis from an intracranial meningioma; (c) origin from arachnoid cells within the sheaths of cranial nerves; and (d) origin from embryonic nests of arachnoid cells. The case we present underwent a complete neuroradiological screening, and, although the neuroradiological findings were nonspecific to provide a correct diagnosis, they were useful for assessment of the tumor extension and for surgical planning. Particularly, magnetic resonance gave a panoramic view of the tumor and suggested its extensive vascularization, which was confirmed later by angiography.