Diagnosis

Neurofibromatosis, Type 1 (NF1)

Diagnosis Definition

  • NF1 is the most common neurocutaneous disorder (phakomatosis) 
  • It is an autosomal dominant mutation of the neurofibromin gene, which is a tumor suppressor gene of the RAS/MAPK pathway, referred to as a rasopathy
  • The diagnosis of NF1 is clinical and criterion-based 

Imaging Findings

  • On MRI, NF1 presents as areas of high signal on T2/FLAIR sequences in the deep white matter and basal ganglia; these areas represent myelin vacuolation that don’t enhance and often resolve during the second decade
  • Optic pathway gliomas are associated with NF1 and are best seen on thin-section fluid sensitive sequences (such as CISS or SPACE);  they typically present as fusiform enlargement of parts of the optic pathways; they may enhance and be accompanied by tortuosity of the nerve and dilatation of the optic nerve sheath 
  • Buphthalmos (enlargement of the globe) can result from increased intraocular pressure
  • Greater sphenoid wing dysplasia may be seen, best on CT, but also on MRI as dark signal cortical enlargement; this feature can result from neurofibromas or CSF pulsation
  • Plexiform neurofibromas are STIR/T2 FS hyperintense fusiform and nodular masses along the course of nerves, often seen coalescing along the brachial, lumbar plexi and various cranial nerves
  • Dural ectasia, a result of cerebrospinal fluid (CSF) pulsation, is seen on T2 sequences as outpouching of high signal CSF into the neural foramina and scalloping of the vertebral bodies

KEY IMAGES

Pearls

  • Another manifestation of NF1 in the brain is moyamoya disease, which is caused by blocked arteries at the base of the brain; the name moyamoya means “puff of smoke” in Japanese and describes the appearance of tiny vessels that form to compensate for the blockage
  • Plexiform neurofibromas may undergo malignant degeneration and surveillance imaging is performed to monitor for new enhancement or growth

References

  1. Ferner RE, Huson SM, Thomas N, et al. Guidelines for the diagnosis and management of individuals with neurofibromatosis 1. Journal of Medical Genetics 2007; 44(2):81-88
  2. Van Meerbeeck S, Verstraete K, Janssens S, Mortier G. Whole body MR imaging in neurofibromatosis type 1. European Journal of Radiology 2009; 69(2):236-242

Case-based learning.
Perfected.

Learn from world renowned radiologists anytime, anywhere and practice on real, high-yield cases with Medality membership.

  • 100+ Mastery Series video courses
  • 4,000+ High-yield cases with fully scrollable DICOMs
  • 500+ Expert case reviews
  • Unlimited CME & CPD hours

Related Diagnosis

Neurofibromatosis, Type 1 (NF1)

Read More

Inverted Papilloma (IP)

Read More

Optic Neuritis (ON)

Read More

Case-based learning.
Perfected.

Try MRI Online Premium for free.

Customers served! 0 +  Mastery Series video courses
Customers served! 0 +  High-yield cases
Customers served! 0 +  Expert case reviews

Unlimited

CME & SA-CME credits

Learn from world renowned radiologists anytime,
practice on real, high-yield cases with MRI Online Premium.

>