Neurofibromatosis with brachial plexus neurofibroma
41yo male with history of neurofibromatosis and multiple neurogenic tumours. MRI monitoring of largest lesion in right supraclavicular fossa and right brachial plexus.
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Innumerable enhancing neurogenic lesions are identified. The largest lesion in the right supraclavicular fossa (that appears to be related to the right C6 nerve root) measures 43 x 52 mm, unchanged. Indentation of the cervical cord by neurogenic tumors arising from the right C6 nerve root and left C4 nerve root is unchanged. No cord signal abnormality. Numerous neurogenic tumors are seen scattered along the cervical cord, involving most neural exit foramen.
There are three main types of neurogenic tumors formed directly from the brachial plexus – benign schwannomas, benign neurofibromas and malignant peripheral nerve sheath tumor (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 fiber
- no capsule
- nerve enters and leaves through the center of the tumor
- no peritumoural edema
- 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 tumor
Case courtesy of A/Prof Pramit Phal.
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