CNS tumor
Other tumors
Schwannoma
Author: Nat Pernick, M.D.
Topic Completed: 1 January 2006
Minor changes: 2 November 2021
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: "Schwannoma" CNS
Table of Contents
Definition / general | Diagrams / tables | Case reports | Treatment | Gross description | Gross images | Microscopic (histologic) description | Positive stains | Negative stains | Electron microscopy description | Molecular / cytogenetics description | Differential diagnosisCite this page: Pernick N. Schwannoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cnstumorschwannoma.html. Accessed December 3rd, 2021.
Definition / general
- Also called neurilemoma; improperly designated as acoustic "neuroma"
- Benign (grade I)
- 7% of intracranial neoplasms
- More common in older adults, women
- Derived from Schwann cells (neural crest derivation)
- Tend to arise on and compress peripheral aspects of nerves, 90% on CN VIII ("acoustic schwannoma"); rare on CN V or VII or other cranial nerves
- In spinal cord, usually attached to dorsal spinal nerve root and may extend into cord
- Bilateral CN VIII tumors: associated with neurofibromatosis type 2 (NF2); NF2 patients also have tumors at unusual locations, meningeal proliferations and gliomas; poorer prognosis is associated with tumors 2 cm or larger and earlier age at onset (J Neurosurg 2003;99:480)
- Symptoms associated with compressed nerve (tinnitus or hearing loss with CN VIII)
- References: eMedicine: Cranial Nerve Schwannoma Imaging
Diagrams / tables
Images hosted on other servers:
Anatomy of acoustic tumor
Case reports
- 19 year old man with intracranial subfrontal tumor (Neurol India 2004;52:248)
- 33 year old woman with intracerebral tumor (Pathol Int 2005;55:514)
- Patient with spinal and intracranial melanotic schwannomas (J Neurooncol 2004;68:249)
Treatment
- Radiation therapy may cause malignant transformation, particularly in children or NF patients (J Med Genet 2006;43:289)
Gross description
- Firm gray masses; may have cystic and xanthomatous change and hemorrhage
- Attached to nerve but can be separated from it
- Does not invade but can displace brainstem and spinal cord
Gross images
Images hosted on other servers:
Acoustic schwannoma
Fish flesh tan cut surface
Microscopic (histologic) description
- Circumscribed and often encapsulated; biphasic (less common at cerebellopontine angle)
- Composed of uniformly spindled Schwann cells with Antoni A (cellular fascicular) and Antoni B (myxoid; vacuolated) regions
- Vessel walls with perivascular hemosiderin; variable Verocay bodies (eosinophilic cores and nuclear palisading)
- Cells are spindled with ill defined cytoplasm, dense chromatin; no axons, no mitotic figures
- Degenerative changes (ancient change): nuclear pleomorphism, xanthomatous change and vascular hyalinization; common but no significance
- May have Rosenthal fibers or eosinophilic granular bodies (Arch Pathol Lab Med 1997;121:1207)
Positive stains
- S100, Leu7; type IV collagen (stains abundant parenchymal reticulin), CD34 (Antoni B areas) and calretinin (Antoni A areas)
- Silver stain shows minimal axons; variable GFAP
Electron microscopy description
- Continuous basement membranes along exterior surface of cells
Molecular / cytogenetics description
- 22q- due to mutations of neurofibromatosis 2 gene in these patients
Differential diagnosis
- Astrocytoma: no abundant parenchymal reticulin
- Fibroblastic meningioma: whorls, psammoma bodies, EMA+
- Hemangiopericytoma
- Solitary fibrous tumor
- Subependymoma
- Tanycytic ependymoma: no abundant parenchymal reticulin
