Testing & Diagnosis for Neurofibromatosis in Children

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Contact the Multidisciplinary Neurofibromatosis Program

How is NF1 diagnosed?

Children can have different pathways to a diagnosis of NF1, but a typical diagnostic process might look like this:

  • The pediatrician notices some café-au-lait spots on the child’s skin (these may look to the parent just like birthmarks). These spots may be present at birth, but more commonly they develop through the first few years of life. Since this is one of the diagnostic criteria of NF1, the pediatrician may recommend that the child schedule an evaluation with our Neurofibromatosis Program.   
  • Our doctors do a complete and thorough physical exam of the child and take her medical, developmental, history and family history. She may also see an ophthalmologist.

 If your child meets the clinical criteria for diagnosis of NF1 at this time, her doctor will make the diagnosis, and discuss next steps with you. The clinical criteria are that she must have at least two of the following:

Symptom

 

General age of appearance

parent or sibling with NF1

 

present at birth

specific abnormality of arm bone (radial dysplasia) or leg bone (tibial dysplasia)

 

present at birth but may not be identified until later

six or more café-au-lait macules

may be present at birth, often the first sign to appear. Seen in 95% of adults with NF.

 

optic glioma (non-cancerous thickening of the optic nerve)

 

N/A. Since doctors don’t regularly screen for these, they’re usually detected when other signs and symptoms of NF appear.

 

freckling in the armpit, groin or neckfolds

 

seen in 90% of children with NF1 by age 6

Lisch nodules (small spots on the iris of the eye that do not affect vision. They aren’t visible to the naked eye, but an ophthalmologist would be able to detect them.)

 

seen in 95% of children with NF1 by age 20

two or more neurofibromas or one plexiform neurofibroma

 

Plexiform neurofibromas are present at birth, but may not be identified until later. Non-plexiform neurofibromas usually appear during the teenage and adult years.

 

 

If your child doesn’t meet the clinical criteria for diagnosis, her doctor will schedule periodic follow-up visits to see if the symptoms develop. In some cases, the doctor may want to do genetic testing.

Keep in mind that between 80 to 85 percent of children with NF1 are diagnosed by the time they’re 6, and 95 percent are diagnosed by age 8. That means that if your child is older than 8 and hasn’t been diagnosed, the likelihood that she has NF1 drops dramatically.

If there’s some uncertainty as to whether my child has NF1, why wouldn’t I just ask for a genetic test?

Most of the time, the results of the test won’t change how we approach your child’s care. The tests are also expensive, and not all insurance companies and plans may cover the cost.

Your physician and genetic counselor will be happy to discuss all of your options with you.

Can doctors identify neurofibromas just by looking at them?

No, a biopsy is needed to confirm that a bump is a neurofibroma. But most of the time, neurofibromas appear after other symptoms of NF1–such as café-au-lait macules and skinfold freckling–have already been identified. So in a child with NF1, we may assume that a new bump is a neurofibroma.

Can NF1 be diagnosed during pregnancy?

If a parent has NF1 and a known mutation, testing can be performed to determine if the baby has inherited the same mutation. But keep in mind that even if the test shows the mutation, it is difficult to know anything about what symptoms the child will develop.

Prenatal diagnosis can be done through:

chorionic villus sampling (CVS)

typically at 10-12 weeks gestation

amniocentesis (tests the amniotic fluid)

typically at 14-15 weeks gestation

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- Sandra L. Fenwick, President and CEO

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