Amyloidoma in the gasserian ganglion: case report.

Background: Amyloidoma in the central nervous system is extremely rare. We describe a rare case of amyloidoma in the gasserian ganglion manifesting as trigeminal neuropathy.

Methods: A 41-year-old woman was admitted to our hospital with progressive numbness and hypalgesia in the distribution of the second and third divisions of the left trigeminal nerve. There was no evidence of chronic inflammatory disorder or immunological abnormalities. Magnetic resonance images showed a mass in the left Meckel's cave that was brightly enhanced with gadolinium.

Results: A reddish, firm mass was successfully removed via a left temporal craniotomy. Histologically, the tumor was composed of larger acellular deposits of eosinophilic material. The acellular deposits were positive for potassium permanganate-resistant Congo red staining, showing apple-green birefringence under polarized light and expression of immunoglobulin lambda light chain-derived proteins (A lambda) immunohistochemically.

Conclusion: The present case revealed an A lambda amyloidoma in the left gasserian ganglion. Although the incidence is rare, amyloidoma should be suspected in patients who complain of progressive trigeminal neuropathies and show an enhanced lesion in the gasserian ganglion on MR images.