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A nerve sheath tumor is a type of tumor of the nervous system (nervous system neoplasm) which is made up primarily of the myelin surrounding nerves. Nerve sheath tumors can be benign or malignant , and may affect both the peripheral and central nervous systems .
A malignant peripheral nerve sheath tumor (MPNST) is a form of cancer of the connective tissue surrounding peripheral nerves. Given its origin and behavior it is classified as a sarcoma. About half the cases are diagnosed in people with neurofibromatosis; the lifetime risk for an MPNST in patients with neurofibromatosis type 1 is 8–13%. [2]
New and more precisely defined entities include malignant melanotic nerve sheath tumor (formerly known as melanotic schwannoma) and hybrid nerve sheath tumors. [4] [5] The majority of peripheral nerve tumors are benign tumors of the nerve sheath (usually schwannomas); on rare occasions, they are metastatic tumors or originate from the nerve cells.
The overall incidence rate of brain tumors in children is 6.2 per 100,000. [10] Glioblastomas are the most aggressive malignant glioma and make up approximately 47.7% of all gliomas, and are more commonly found in males. [10] [16] Their incidence rate is 3.23 per 100,000 people. [10] The 5-year survival rate for glioblastoma is only 6.8%. [10]
Meningiomas, which develop in the meninges, are common primary brain tumors, representing approximately 37% of all brain tumors. [15] The incidence rate for meningiomas is 9.51 per 100,000 people. [9] Unlike gliomas, more than 98% of meningiomas are nonmalignant [15]. The 5-year survival rate for nonmalignant meningiomas is approximately 91%. [9]
Malignant peripheral nerve sheath tumor (includes epithelioid variety) ... Pediatric rhabdomyosarcoma patients have a 50–85% long term survival rate. [23]
Malignant melanotic nerve sheath tumor (previously known as melanotic schwannoma) is a rare aggressive peripheral nerve sheath tumor that typically develops in conjunction with spinal or visceral autonomic nerves, consisting uniformly of Schwann cells displaying melanocytic differentiation.
Primitive neuroectodermal tumor is a malignant (cancerous) neural crest tumor. [1] It is a rare tumor, usually occurring in children and young adults under 25 years of age. The overall 5 year survival rate is about 53%. [2]