CNS tumor
Mesenchymal and other tumors
Schwannoma

Author: Nat Pernick, M.D. (see Authors page)

Revised: 12 September 2017, last major update January 2006

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: "Schwannoma" CNS

Cite this page: Pernick, N. Schwannoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/cnstumorschwannoma.html. Accessed December 13th, 2017.
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
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

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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)
Microscopic (histologic) images

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Antoni A areas and Verocay bodies

Black arrow: Antoni A; blue arrow: Antoni B

High power

Positive stains
Negative stains
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