The neurofibromatoses represent three distinct disorders characterized by tumors along the peripheral nerves and a collection of symptoms. Although neurofibromatosis is not itself a cancer, it can be associated with certain malignancies.
Neurofibromatosis type 1 (NF1) is a common autosomal dominant genetic disorder that affects approximately 1 in 3,000 people. Whether NF1 is inherited or arises spontaneously, it can cause a variable range of symptoms. Rarely, NF1 can be associated with malignancies such as optic pathway glioma, gastrointestinal stromal tumor (GIST), pheochromocytoma, juvenile myelomonocytic leukemia (JMML) and sarcoma (malignant peripheral nerve sheath tumor or MPNST). In these cases surgery, chemotherapy and radiation may be included as treatment options.
Neurofibromatosis type 2 (NF2) is a rare autosomal dominant genetic disorder that affects approximately 1 in 25,000 people, and is sometimes inherited in families or may arise spontaneously. NF2 most commonly causes dysfunction of the vestibular nerve. Consequently, hearing loss, ringing in the ears (tinnitus) and problems with balance are generally the first symptoms of NF2, although other symptoms may occur first.
Schwannomatosis is the rarest form of neurofibromatosis and has only recently been defined. It may affect as many as one in 40,000 people. The condition causes multiple schwannomas on cranial, spinal and peripheral nerves, but without bilateral vestibular schwannoma development seen in NF2. People with schwannomatosis often have problems with pain, which may be their only symptom. Schwannomatosis is a genetic condition, but unlike NF1 and NF2 it does not have a clear pattern of inheritance and most commonly occurs sporadically.
Diagnoses for these disorders are made either based on clinical criteria or genetic testing. To find out more about these conditions please see Johns Hopkins Comprehensive Neurofibromatosis Center in the Department of Neurology and Neurosurgery.