Neurofibromatosis Type 1

KEY FACTS

TERMINOLOGY

• Neurofibromatosis type 1 (NF1), von Recklinghausen

disease, peripheral neurofibromatosis

IMAGING

• Benign hyperintense white matter (WM) lesions on T2WI in

70-90% of preteen children

○ Lesions are poorly defined, no mass effect/enhancement

○ May also involve cerebellar WM, globus pallidus,

thalamus, brainstem

○ Wax, then wane; disappear by 20 years of age

• Neoplasms

○ Plexiform neurofibromas

– Sphenoid wing and occipital bone dysplasia found in

association with plexiform tumors

○ Optic pathway gliomas (OPGs)

○ Parenchymal gliomas

• Vascular dysplasias → stenosis, moyamoya, aneurysm

PATHOLOGY

• Autosomal dominant; gene locus is chromosome 17q12

• Gene product is neurofibromin (negative regulator of RAS

protooncogene)

○ Neurofibromin also regulates neuroglial progenitor

function

○ Required for normal glial and neuronal development

○ Inactivated in NF1 → tissue proliferation, tumor

development

• Focal areas of signal intensity related to (transient)

intramyelinic edema

CLINICAL ISSUES

• ~ 50% have macrocephaly; in part secondary to ↑ WM

volume

• OPG can cause progressive vision loss

• Café au lait spots are earliest finding

• Most common neurocutaneous and inherited tumor

syndrome

(Left) Axial graphic shows

enlarged right middle cranial

fossa, dysplastic sphenoid

wing, and a large

orbital/periorbital plexiform

neurofibroma. Note the

exophthalmos and

buphthalmos of the involved

globe ﬇. (Right) Gross

pathology of optic pathway

glioma (top) shows classic

well-delineated fusiform

enlargement of the optic

nerve. Axial T2WI (bottom)

shows optic nerve glioma ﬊

enlarging the left optic nerve.

Note anterior displacement

and posterior deformity of the

globe ﬈.

(Left) Axial T2FS MR in an 18-

month-old child shows an

extensive plexiform

neurofibroma infiltrating the

scalp and orbit and extending

into the cavernous sinus

through the superior orbital

fissure. Note the bag of worms

appearance ﬊. (Right) Axial

T2WI in a 4-year-old child with

neurofibromatosis type 1

shows 2 prominent

hyperintense foci ﬈ in the

right internal capsule. The

lesions disappeared by age of

15 years.

Trauma, and Stroke

Brain: Pathology-Based Diagnoses: Malformations,

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