Trigeminal amyloidoma: case report and review of the literature

The authors present a case of amyloid infiltration involving the trigeminal nerve that mimicked a malignant cavernous sinus tumor with perineural tumor infiltration. A 64-year-old man presented with trigeminal nerve numbness. Imaging revealed a plaque-like enhancing lesion along the right lateral cavernous sinus extending anteriorly into Meckel's cave and involving the proximal V2 and V3 trigeminal nerves. The patient underwent extradural frontotemporal craniotomy with middle fossa exposure of the cavernous sinus to diagnose and treat the presumed malignant cavernous sinus tumor. A reddish mass involving the lateral dural wall of the cavernous sinus was resected. There was also enlargement of the gasserian ganglion and second and third divisions of the trigeminal nerve, the latter of which was biopsied. Permanent histopathological studies demonstrated microscopic eosinophilic, amorphous material, which stained positive for Congo red, and absence of neoplastic cells. The final diagnosis was amyloidoma. Thus, amyloidomas may occur from the trigeminal nerve or ganglia and should be considered in the differential diagnosis of a cavernous sinus lesion mimicking a tumor. The few reports of trigeminal amyloidomas are reviewed and the presentation, imaging, and management of this skull base lesion are discussed. Overall, patients may have symptomatic improvement of trigeminal neuropathy with resection of the amyloidoma outside of the nerve capsule that is compressing the nerve, while resection of the lesion from within the capsule may result in permanent trigeminal nerve dysfunction.