How can you distinguish a neurofibroma from a schwannoma?
When solitary it can be impossible. In this case many of the neurofibromas are plexiform in nature, involving the whole brachial plexus and extending across multiple soft tissue spaces and along multiple nerves. This is characteristic of plexiform neurofibromas and is not a feature of schwannomas.
What feature seen best on axial T2 images, is more characteristic of neurofibromas?
A hyperintense rim and central area of low signal (“target sign”) may be seen; this is thought to be due to a dense central area of collagenous stroma. Although this sign is highly suggestive of neurofibroma, it is occasionally also seen in shwannomas and malignant peripheral nerve sheath tumours.
Very extensive features consistent with neurofibromatosis are demonstrated, involving all imaged regions. These are unchanged when compared to previous imaging.
The largest intraspinal neurofibroma is located in the lumbar spine, posterior to the vertebral body of L2 and L3, where the entire canal is filled, with associated bony remodelling. The thoracic canal is relatively uninvolved without significant distortion of the thoracic cord. The cervical canal is most stenosed at the level of C2/3 were bilateral neurofibromas distorting and compressing the cervical cord.
Bilaterally the brachial plexuses and lumbar plexuses and intercostal nerves are extensively involved with numerous other neurofibromas throughout the soft tissues.