Presentation
Bilateral abduction deficit consistent with a sixth cranial nerve palsy. Decreased sensation on the face, especially in the cranial nerve V2 and V3 distribution.
Patient Data
ASNR Case of the Day Winner 2023
This case was selected as the winner of the 2023 ASNR Case of the day competition winner. Runner-up and honourable mentions can be viewed in this playlist.
There is an enhancing mass within the left cavernous sinus and trigeminal (Meckel's) cave. The enhancement extends inferiorly along the mandibular segment of the trigeminal nerve, towards the inferior alveolar nerve. There is atrophy of the masticator muscles on the left. The enhancement extends anteriorly along the foramen rotundum with involvement of the pterygopalatine fissure and retromaxillary space.
There is also enhancement extending anteriorly within the left inferior orbital fissure.
There is cisternal enhancement of the oculomotor, trigeminal, abducens, facial and glossopharyngeal nerves.
Case Discussion
This is a case of an amyloidoma (tumoural amyloidosis) affecting the trigeminal nerve, particularly the mandibular nerve (CN V3). The involvement of CN V3 likely explains the atrophic masticator muscles on the left, secondary to denervation.
The patient underwent excision of the lesion within the left cavernous sinus and foramen ovale. Gross examination of the resected mass revealed a tan-pink fibrous tissue.
Histopathologic analysis with haematoxylin and eosin stained slides showed fragments of fibrous tissue and nerve tissue admixed with foci of amorphous eosinophilic material deposits in sub-perineurial region within the nerve fascicles and in the peri-epineurial soft tissue. No granulomas or vasculitis were identified. The amorphous material was congophilic and showed apple green birefringence in polarised light. The axonal component of the nerve was highlighted by neurofilament stain.
The specimen was further sent for amyloid typing. Again, the specimen was congo red positive. Liquid chromatography tandem mass spectrometry (LC MS/MS) was performed on peptides extracted from Congo red-positive, microdissected areas of the paraffin-embedded specimen. The LC MS/MS detected a peptide profile consistent with AL (kappa)-type amyloid deposition.
The patient is currently followed by a multi-specialty team as an outpatient. The patient has had several tests including a fat pad biopsy to assess if he has localised (trigeminal nerve) versus systemic amyloidosis. Currently, all tests for systemic amyloidosis have been negative.
This is a rare phenomenon with only a few reported cases in the literature.1,2
Unable to process the form. Check for errors and try again.