Intracranial examples are rare with only 7 documented cases including the present report 1-5 . Of several reported examples of malignant schwannomas in the sinonasal region, the case of Fernandez et al. These tumours comprise a small fraction of all peripheral nerve tumours and are rare lesions in the head and neck. Most of the latter are found in distal branches of the trigeminal nerve. They have been reported to develop within a schwannoma 10 or ganglioneuroma 11 and in association with radiation therapy 12 .
Examples affecting cranial nerves are understandably smaller at the time of presentation.
Large calibre nerves are most frequently involved, especially in the extremities, neck, mediastinum and retroperitoneum. Intracranial nerves are rarely involved. It is noteworthy that none of the seven intracranial examples had NF1 or a family history of NF1 which is in sharp contrast to those arising in more peripheral sites. Intracranial involvement is associated with a poor prognosis and hematogenous metastasis is not uncommon. Pathology Gross examination typically reveals a fusiform or plexiform enlargement of the nerve.