Neurofibromatosis causes tissue along the nerves to grow uncontrollably. This growth can put pressure on affected nerves.
If the growths are in the skin, there are no major symptoms. If the growths are in other nerves or parts of the body, they can cause pain, severe nerve damage, and loss of function in the area the nerve affects. Problems with feeling or movement can occur, depending on which nerves are affected.
The condition can be very different from person to person, even among people in the same family who have the same NF1 gene change.
"Coffee-with-milk" (cafe-au-lait) spots are the hallmark symptom of neurofibromatosis. Many healthy people have 1 or 2 small cafe-au-lait spots. However, adults who have six or more spots that are bigger than 1.5 cm in diameter (0.5 cm in children) could have neurofibromatosis. In some people with the condition, these spots may be the only symptom.
Other symptoms may include:
- Freckles in the underarm or groin
- Large, soft tumors called plexiform neurofibromas, which may have a dark color and may spread under the surface of the skin
- Pain (from affected nerves)
- Small, rubbery tumors of the skin called nodular neurofibromas