NEUROFIBROMATOSIS

Familial Neurocutaneous Tumor Disease

Neurofibromatosis is a familial neurocutaneous disorder. It affects skin and nerves. It’s autosomal dominant. There are two types.

1. Neurofibromatosis Type 1 (NF1) is very common (1 in 3000 people), making it the most common genetic disease of the nervous system. NF1 is autosomal dominant, and it affects the PNS. The NF1 gene is on chromosome 17, and it encodes for a tumor suppressor protein found in some neurons called neurofibromin. NF1 starts in infancy. Here are some of the symptoms:

   1. All patients have brown skin discolorations called “café au lait spots”

   2. Neurofibromas are common. These are peripheral nerve skin tumors, and they look like little flesh colored skin lumps.

   3. Most patients have brown spots in their irises called “Lisch Nodules” and tumors on their optic nerves called optic gliomas.

   4. Plexiform neurofibromas (big bulging skin flaps) occur only 30% of the time, however they are absolutely pathognomonic for NF1. 

   5. Another benign tumor that appears comes out of the arachnoid membrane, called a meningioma. It may cause seizures

   6. Optic nerve gliomas, which can cause a host of unusual ocular symptoms.

   7. Mild cognitive problems are present in about 90% of patients.

2. Neurofibromatosis Type 2 (NF2) is a little more rare. This autosomal dominant condition affects a gene on chromosome 22 (Two 2’s) that encodes for a different tumor suppressor called merlin. Here are the symptoms:

   1. Bilateral acoustic neuromas, a benign tumor of CN 8, occur 80% of the time. Two acoustic neuromas.

   2. Cataracts. Two eyeballs

   3. Other weird CNS tumors (meningiomas, gliomas)