A nerve sheath tumor is a type of
tumor
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
of the
nervous system
In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes ...
(
nervous system neoplasm
A nervous system neoplasm is a tumor affecting the nervous system. Types include:
* Nerve sheath tumor
* Brain tumor
* Arachnoid cyst
* Optic nerve glioma
Optic nerve glioma (or optic glioma), a form of glioma which affects the optic nerve, is ...
) which is made up primarily of the
myelin
Myelin is a lipid-rich material that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon. The myelinated axon can be ...
surrounding
nerves. From benign tumors like schwannoma to high grade malignant neoplasms known as malignant peripheral nerve sheath tumors, peripheral nerve sheath tumors include a range of clearly characterized clinicopathologic entities.
A peripheral nerve sheath tumor (PNST) is a nerve sheath tumor in the
peripheral nervous system
The peripheral nervous system (PNS) is one of two components that make up the nervous system of bilateral animals, with the other part being the central nervous system (CNS). The PNS consists of nerves and ganglia, which lie outside the brain ...
.
Benign
Malignancy () is the tendency of a medical condition to become progressively worse.
Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...
peripheral nerve sheath tumors include
schwannoma
A schwannoma (or neurilemmoma) is a usually benign nerve sheath tumor composed of Schwann cells, which normally produce the insulating myelin sheath covering peripheral nerves.
Schwannomas are homogeneous tumors, consisting only of Schwann cells ...
s and
neurofibroma
A neurofibroma is a benign nerve-sheath tumor in the peripheral nervous system. In 90% of cases, they are found as stand-alone tumors (solitary neurofibroma, solitary nerve sheath tumor or sporadic neurofibroma), while the remainder are found in p ...
s.
A
malignant peripheral nerve sheath tumor
A malignant peripheral nerve sheath tumor (MPNST) is a form of cancer of the connective tissue surrounding nerves. Given its origin and behavior it is classified as a sarcoma. About half the cases are diagnosed in people with neurofibromatosis; t ...
(MPNST) is a
cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
ous peripheral nerve sheath tumor, which are frequently resistant to conventional treatments.
Origin of peripheral nerve sheath tumors
The primary Schwann cell differentiation and neoplastic proliferations are characteristics of peripheral nerve sheath tumors. For instance, the Schwann cell, which is the major neoplastic cell component of neurofibroma, is cytologically distinguished by the expression of S-100 protein and wavy nuclear outlines. A variety of peripheral nerve cells, including axons, perineurial cells, fibroblasts, and varying inflammatory components such mast cells and lymphocytes, are also present in neurofibromas. A population of CD34-positive cells with an unknown histogenesis is also found.
[Weiss SW, Nickoloff BJ. CD-34 is expressed by a distinctive cell population in peripheral nerve,
nerve sheath tumors, and related lesions. Am J Surg Pathol. 1993; 17:1039–1045. ubMed:
7690524/ref>
]
References
External links
Nervous system neoplasia
{{neoplasm-stub