There are three main types of neurogenic tumours formed directly from the brachial plexus – benign schwannomas, benign neurofibromas and malignant peripheral nerve sheath tumour (MPNST).
One-third of neurofibromas are associated with neurofibromatosis. It is important to distinguish neurofibromas as solitary lesions can often be removed without nerve damage 1.
Although it may be difficult to distinguish between neurofibromas and schwannomas on MRI, some of the more typical MRI features of neurofibroma are listed below 1-4:
- fusiform distension of the nerve with diffuse loosening of the nerve fibre
- no capsule
- nerve enters and leaves through the centre of the tumour
- no peritumoural oedema
- signal intensity
- similar to muscle on T1-weighted images, marked increased intensity on T2-weighted images
target sign (as demonstrated in this case) – hyperintense rim of myxoid tissue with central hypointense area of fibrocollagenous tissue on T2-weighted imaging – appears in 58% of neurofibromas and 15% of schwannomas
- central homogenous enhancement with gadolinium contrast
- associated features
- can have mild muscle atrophy distal to tumour
Case courtesy of A/Prof Pramit Phal.