neurofibromatosis type 1

Optic nerve glioma

An optic pathway glioma is a low-grade tumor of the nerves connecting the eyes to the brain. It is one of the tumors children with the condition are watched for, since it can affect vision.

Astrocytoma

Astrocytomas are tumors that grow from star-shaped support cells (astrocytes) in the brain. In NF1 they can occur, often in the midline of the brain, and these tumors generally have a good outlook.

Glioma

Gliomas are tumors that arise from the supporting (glial) cells of the brain and nervous system. In NF1 they are among the tumors that can develop, alongside other changes such as skeletal differences and learning difficulties.

Lisch nodules

Lisch nodules are tiny harmless growths on the iris of the eye. They do not affect vision but are a useful diagnostic sign, found with an eye examination.

Malignant peripheral nerve sheath tumor

A plexiform neurofibroma can, in a minority of people, change into a cancer called a malignant peripheral nerve sheath tumor. New or rapidly growing pain, or a lump that changes, is a reason to seek prompt evaluation.

Plexiform neurofibroma

Plexiform neurofibromas are larger tumors that grow along the length of a nerve. They are a common complication, can be present from birth, are often hard to remove surgically, and may cause pain or press on nearby structures.

Neurofibroma

Neurofibromas are soft, benign tumors that grow on nerves, usually appearing as bumps on or under the skin from later childhood onward.

Tibial pseudarthrosis

A specific bone problem is tibial pseudarthrosis, where the shin bone fails to heal normally, sometimes after a fracture, and forms a false joint. It is one of the distinctive skeletal features.

Hydrocephalus

Hydrocephalus is a buildup of fluid in the spaces of the brain. It can occur in NF1, sometimes together with changes in the lining around the spinal cord.

Specific learning disability

Learning difficulties are common in NF1 and are one of its developmental effects, separate from the tumors. Recognizing them early allows for school support.

Seizure

Seizures can occur in NF1. In one hospital-based group of people with NF1, about 11 in 100 had some form of epilepsy (a tendency to recurrent seizures).

Hypertension

High blood pressure (hypertension) can occur in NF1. It may come from changes in the blood vessels themselves, which can also lead to ballooning of a vessel wall (an aneurysm).

Autosomal dominant inheritance

NF1 is inherited in an autosomal dominant pattern, so a child of an affected parent has a 1 in 2 chance of inheriting it. About half of cases instead arise from a new (de novo) gene change in someone with no family history.

Sphenoid wing dysplasia

NF1 can affect bone development. One of the distinctive bone changes is dysplasia of the sphenoid wing, a bone behind the eye.

Scoliosis

Bone problems can occur, including scoliosis, a sideways curvature of the spine.

Freckling

Freckling in NF1 means clusters of small freckle-like spots, typically in skin folds such as the armpits and the groin. It is one of the characteristic features of the condition, appearing alongside cafe-au-lait macules, Lisch nodules, skeletal changes, and neurofibromas.

Inguinal freckling

Freckling in the groin (inguinal) folds is another characteristic skin sign, again in areas not exposed to the sun.

Multiple cafe-au-lait spots

Multiple café-au-lait spots, flat light-brown patches on the skin, are usually the earliest sign and often appear in infancy. Having six or more is one of the key diagnostic features.

Axillary freckling

Freckling in the armpits is a characteristic sign. Unlike ordinary freckles it appears in skin folds that are not exposed to the sun.

Neurofibromatosis, type 1

Diagnosed using: NIH diagnostic criteria (revised 2021).

Neurofibromatosis, type 1

Diagnosed using: NF1 genetic testing.

Neurofibromatosis, type 1

Diagnosed using: ophthalmologic examination.

selumetinib

Selumetinib is a targeted medicine (a MEK inhibitor) that blocks the overactive growth pathway in the tumors. It is used for children with symptomatic, inoperable plexiform neurofibromas, where it can shrink the tumor and reduce pain.

Used to help with: Plexiform neurofibroma.

mirdametinib

Mirdametinib is a targeted medicine (a MEK inhibitor) that blocks the overactive growth signaling driving NF1 tumors. It is approved for symptomatic plexiform neurofibromas that cannot be removed by surgery, in both children and adults.

Used to help with: Neurofibromatosis, type 1.

surgical resection

Surgery to remove tumors is one way the neurofibromas of NF1 are managed. It is not always possible, though: plexiform neurofibromas are a common complication of NF1 that are often inoperable and can come back after removal.

Used to help with: Neurofibromatosis, type 1.