Spinal neurofibromas are benign peripheral nerve sheath tumors, usually of the localized subtype.
This article specifically relates to spinal neurofibromas. For a general discussion of neurofibromas, including their epidemiology and pathology, refer to neurofibroma. For a discussion of the general radiographic features of neurofibromas, refer to spinal nerve sheath tumors.
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Clinical presentation
Spinal neurofibromas are often asymptomatic 1. If symptoms are present, they usually include pain and/or radicular sensory changes due to the typical location along the dorsal sensory roots. Weakness is less common. As multiple lesions are common, patients may present with multiple radiculopathies. Myelopathy may occur if the lesion is large.
Radiographic features
When located along spinal nerve roots, they are most frequently encountered along the cervical cord. They are difficult/impossible to categorically distinguish from schwannomas.
As they are slow growing they remodel the adjacent bone, often resulting in widening of the neural exit foramen with thinning of the pedicle and posterior vertebral body scalloping.
CT
- well-defined hypodense mass
- frequently causing widening of the neural foramen with extraspinal extension: dumbbell shape 5
- however this shape is not specific and can be seen with schwannomas and meningiomas 5
- minimal or no contrast enhancement
MRI
- T1: hypointense
-
T2: hyperintense
- 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 schwannomas and malignant peripheral nerve sheath tumors
- T1 C+ (Gd): heterogenous enhancement
Refer to spinal nerve sheath tumors for further discussion of radiographic appearances.
Treatment and prognosis
Neurofibromas are slow growing. Surgery is the treatment of choice for symptomatic lesions. However, as neurofibromas tend to encase the nerve roots, they usually cannot be dissected from the parent nerve 4. 5-10% of neurofibromas undergo malignant change 3, which may be indicated by rapid growth.
Differential diagnosis
The main differential for spinal neurofibromas includes:
For a more comprehensive discussion of the differential diagnosis please refer to the genertic article on spinal nerve sheath tumors.
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