In general, the cause or causes of peripheral nerve sheath tumors are unknown. However, two kinds of benign peripheral nerve tumors, schwannomas and neurofibromas, may be caused by the conditions schwannomatosis and neurofibromatosis (both type 1 and type 2), respectively. These are inherited conditions that can cause tumors to grow on nerves. Neurofibromatosis type 1, in particular, can lead to multiple neurofibromas and even malignant peripheral nerve sheath tumors, although these are rare.
People of both genders and all ages can be affected by peripheral nerve sheath tumors. Sporadic malignant tumors are most common in those between the ages of 40 and 50, while those associated with neurofibromatosis type 1 are usually diagnosed between the ages of 30 and 40.