Granular cell tumour of the cavernous sinus: A rare cause of secondary trigeminal neuralgia.

Background: Cavernous sinus tumours comprise 0.1-0.2% of all intracranial tumours, and are most commonly meningiomas or schwannomas. Central nervous system and cranial nerve granular cell tumours (GCTs) are extremely rare. We report the tenth case of a GCT arising from a cranial nerve, and the second case reported in a cavernous sinus location, and review the literature. Clinical presentation: A 67-year-old man presented with right sided trigeminal neuralgia. Imaging findings suggested a trigeminal schwannoma and he was treated with CyberKnife radiosurgery. Over a period of 41 months follow up, there was a progression in both symptoms and imaging findings, requiring debulking surgery. Histopathology identified a GCT. Conclusions: This is the first case of a cranial nerve GCT treated with stereotactic radiosurgery. Trigeminal nerve GCTs are a rare differential in cases of presumed schwannomas.