Types of Neurofibromatosis
There are three types of neurofibromatosis.
Neurofibromatosis Type 1
Neurofibromatosis Type 1 (NF1) is caused by a mutation on chromosome 17, and it can cause the presence of multiple birth marks called café au lait macules in a baby, as well as abnormal bone growth and sometimes the slow growth of a benign tumor. Starting in late childhood, people with NF1 may notice the appearance of bumps on their skin, or just under the surface of the skin. These bumps are called neurofibromas and they stop growing at a certain size, usually less than one inch. A small percentage of children with NF1 can have tumors that grow within the nerves behind the eye known as optic pathway glioma.
Some people with NF1 have plexiform neurofibromas, which often look like soft overgrown tissues. Plexiform neurofibromas can be located anywhere on or inside the body. While these tumors are benign (meaning they grow very slowly and do not move to other organs in the body), there is a 10 percent chance that they can turn into cancer at some point. For this reason, it is important to follow regularly with an NF specialist who knows how and when to get imaging of the tumors, and what warning signs to look out for. Our NF patients are also at greater risk of other types of tumors including breast cancer, adrenal gland cancer, neuroendocrine cancers, and leukemia, as well as other health concerns such as high blood pressure, heart disease, and stroke. An NF specialist can pay attention to all these potential needs of people with NF1.
Neurofibromatosis Type 2
Neurofibromatosis Type 2 (NF2) is caused by a completely different mutation on a different gene located on chromosome 22. You might ask why these different conditions are both called neurofibromatosis. The reason is that in both conditions tumors tend to grow alongside the nerves. Whereas in NF1, the tumors occur in the small nerves of the skin and the large nerves inside your body, in NF2, tumors primarily affect the auditory nerves that connect the ears to the brain and control hearing. NF2 patients can also develop tumors in the nerves of their body. The risk of cancer is very low in NF2, but tumors can still lead to deafness, pain, weakness and/or numbness. People with NF2 are also at risk of other tumors arising from the tissue wrapping around the brain and spinal cord (meningiomas), and tumors occurring in the deep fluid filled spaces of the brain and spinal cord (ependymomas).
Schwannomatosis (pronounced shwa-NO-ma-TO-sus) has sometimes been referred to as Neurofibromatosis Type 3 (NF3). Like NF2, tumors grow along nerves in the body and in the auditory nerve, but people with schwannomatosis are at much lower risk of becoming deaf in both ears than in NF2. People with this condition can sometimes lose hearing in one ear due to tumor growth. Schwannomatosis mostly causes pain throughout the body due to irritation of the nerves. This condition can be difficult to diagnose or to distinguish from NF2 because of overlapping symptoms. There is almost no risk of cancer in tumors associated with schwannomatosis, but sometimes people with this condition can develop meningiomas, similar to NF2.