HomeResearchIntramural ResearchClinical ResearchCurrent NHGRI Clinical StudiesThe Study of Disease Severity in Adults with NF1 NF1 Diagnostic Criteria

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The Study of Disease Severity in Adults with NF1 and
The Study of Neurofibroma Growth in Adults with NF1

Overview: The Disease Severity Study Overview: The Tumor Growth Study General Information About NF1 FAQ About the Disease Severity Study FAQ About the Tumor Growth Study Diagnostic Criteria Online Resources for NF1 Study Updates Contact Information

Diagnostic Criteria for NF1

Doctors diagnose NF1 by finding changes in the nerves, skin, bones and eyes. A family history (or pedigree) of relatives with and without the disease is also useful.

Until the late 1980s there was a lot of confusion about the two kinds of NF. A group of doctors with experience in NF met at the National Institutes of Health (NIH) in 1988 to set some rules about diagnosing NF1. There is a separate set of rules for NF2. The rules for NF1 are listed below, in the original medical language. A "plain English" translation of the medical terminology follows.

NF1 is present in a patient who has two or more of the following signs:

1. Six or more café-au-lait macules > 5 mm in greatest diameter in prepubertal individuals or > 15 mm in greatest diameter after puberty.
   
   
2. Two or more neurofibromas of any type or one or more plexiform neurofibromas.
   
   
3. Freckling in the axilla or inguinal region.
   
   
4. A tumor of the optic pathway.
   
   
5. Two or more Lisch nodules.
   
   
6. A distinct osseous lesion, such as sphenoid wing dysplasia or thinning of the cortex of the long bones (with or without pseudoarthrosis).
   
   
7. A first-degree relative (parent, sibling, offspring) with NF1 by the above criteria.
   
   

What does this mean?

Translated into plain English, to have NF1 you must have two or more of the following six signs:

1. Six or more café-au-lait macules (coffee-colored spots on the skin). To "count" a spot, it must be a certain size. The size of the spots depends on whether you are an adult or child. For adults the spots must be 15 mm (a little more than 1/2 inch). For children the spots must be at least 5 mm (about a 1/4 inch).
   
   
2. Neurofibromas are soft fleshy tumors. Doctors simply count the number of these on your skin (often with your help). A plexiform neurofibroma is larger, more complex neurofibroma that involves many nerves. They can be harder to find, since they are sometimes deep in the body.
   
   
3. People with NF1 can get freckling (usually seen on faces, arms and backs) in more unusual places. If a doctor sees freckling in one of your armpits or in your groin, it is a sign of NF1.
   
   
4. The "optic pathway" is the connection that carries signals from the eye to the section of the brain that turns those signals into images. Tumors of the optic pathway are a certain kind of common, usually benign tumor that affect children. They can be found with a brain MRI or an eye exam.
   
   
5. Lisch nodules are small benign tumors of the eye. They are seen in the iris (the colored ring) of your eye. An eye doctor with the help of a special lamp and camera (called a slit-lamp) counts them. Lisch nodules are very helpful in figuring out if someone has NF1 because they are not seen in any other disease.
   
   
6. Sphenoid wing dysplasia and thinning of the cortex of the long bones and pseudoarthosis are changes in the bones that are unique to NF1. They are rare findings in NF1 but are not seen in any other diseases. They can be seen with X-rays. Pseudoarthosis is a fracture (or break) in a leg bone that does not heal well and can cause a lot of problems.
   
   
7. If a family member (parent, child, brother or sister) also has NF1, that "counts" as one of the findings to make the diagnosis.
   
   

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Last Reviewed: April 29, 2009