In younger kids or in those with mild cases, NF1 can be found early when café-au-lait spots (birthmarks) appear on the skin.

Many people without NF1 have one café-au-lait spot. But if a young child has more than five of these birthmarks, at least ? inch in diameter (roughly the size of a dime), a doctor will look for other clues that may indicate NF1. Other signs of NF1 include freckling in the armpits and groin areas, as well as neurofibromas - tumors on, under, or hanging off the skin - and Lisch nodules, tiny, noncancerous bumps on the iris (the colored part of the eye). Although Lisch nodules help identify a person with NF1, they don’t cause any vision problems.

Neurofibromas can be on various parts of the body, often right before puberty starts.

People with NF1 may also have bone problems, such as the thinning or overgrowth of the bones in the arms or lower leg, or scoliosis, an abnormal curving of the spine. 

NF2 isn't usually diagnosed until a child is older. Hearing loss in the late teens and early 20s, is often the first symptom of the disorder, and is caused by tumors growing on the vestibular nerves. The vestibular nerves carry electrical impulses from the ear to the brain, allowing us to hear, and these tumors can occur on one or both sides. 

Other symptoms of NF2 include continuous ringing in the ears, headache, facial pain, or weakness, and feeling unsteady or off-balance.

Other tumors may involved the lining of the brain (meningiomas) and spinal cord (ependymomas). Young children also may have problems with the retina in the back of the eye.