Neuropathology tumours

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The article covers CNS tumours, including brain tumours. They are relatively common and mostly real badness. Tumours are a large part of neuropathology.

The article also includes peripheral nerve sheath tumours.

Brain tumours

Adult

Four most common types of brain tumours:[1]

  1. Metastatic brain tumours (barely edges out primary tumours)
  2. Glioblastoma aka glioblastoma multiforme.
  3. Anaplastic (malignant) astrocytoma.
  4. Meningioma.

Children

  1. Astrocytoma.
  2. Medulloblastoma.
  3. Ependymoma.

Astrocytomas

  • Pilocytic astrocytomas (WHO Grade I).
  • Dysembryoplastic neuroepithelial tumour (DNT), (WHO Grade I).
  • Low-grade (diffuse) astrocytomas (Grade II).
  • Anaplastic astrocytomas (Grade III).
  • Glioblastoma (Grade IV).

Features:[2][3]

  • Nuclear pleomorphism.
  • Mitotic figures.
  • Microvascular proliferation or necrosis with pseudopalisading tumour cells.
    • Pseudopalisading tumour cells = high tumour cell density adjacent to regions of necrosis; palisade = a fence of pales forming a defense barrier or fortification.

Filum terminale

  • Bottom end of the spinal cord - has a limited differential.

DDx:[4]

  • Meningioma.
  • Myxopapillary ependymoma.
  • Neurofibroma.
  • Schwannoma.
  • Paraganglioma.

Pilocytic astrocytoma

General

  • Low-grade astrocytoma.
  • Classically in the cerebellum in children.
  • The optic glioma associated with neurofibromatosis 1.

Gross

  • Do NOT smear.

Microscopic

DDx (of Rosenthal fibers):[5]

  • Chronic reactive gliosis.
  • Subependymoma.
  • Ganglioma.
  • Alexander's disease (rare leukodystrophy).

Oligodendroglioma

General

  • Arise from oligodendrocytes.

Usual location:

  • Fourth ventricle.
  • Intramedullary spinal cord.

Microscopic

Features:

  • Highly cellular lesion composed of:
    • Cells resembling fried eggs (oligodendrocytes) with:
      • Round nucleus - key feature.
      • Distinct cell borders.
      • Moderate-to-marked nuclear atypia.
      • Clear cytoplasm - useful feature (if present).
        • Some oligodendrogliomas have eosinophilic cytoplasm with focal perinuclear clearing.
    • Acutely branched capillary sized vessels - "chicken-wire" like appearance.
      • Abundant, delicate appearing; may vaguely resemble a paraganglioma at low power.
  • Calcifications - important feature.[6]

Images:

Notes:

  • Few neural tumours have round nuclei - DDx:
    • Oligodendroglioma.
    • Lymphoma.
    • Clear cell variant of ependymoma.
    • Germ cell tumour (dysgerminoma/seminoma).

IHC

Features:

  • GFAP +ve.
  • EMA +ve.

Molecular pathology

Losses of 1p and 19q both helps with diagnosis and is prognostic:[7]

  • Greater chemosensitivity
  • Better prognosis.

Peripheral nerve sheath tumours

A classification:[8]

  • Benign:
    • Schwannoma.
    • Neurofibroma.
    • Perineurioma.
    • Traumatic neuroma.
  • Malignant:
    • Malignant peripheral nerve sheath tumour (MPNST).

Meningioma

General

  • Common.
  • Extra-axial. (???)
  • Most are benign.
    • May be malignant.

Microscopic

Features:

  • Whorled appearance - key feature.
  • Calcification.
  • Prominent thick-walled blood vessels.

Many subtypes exist:

  • Atypical meningioma.
    • Has invasion of the brain - WHO Grade 2.
  • Angiomatous meningioma.
  • Others.

Image: Meningioma (neuropathologyweb.org).

DDx:

  • Cerebral angioid angiopathy. (???)

Schwannoma

  • Tumour of tissue surrounding a nerve.
    • Axons adjacent to the tumour are normal... but may be compressed.

Histology

Antoni tissue:[8]

Antoni A

  • Cellular.
  • 'Fibrillary, polar, elongated'.

Comment: May look somewhat like scattered matchsticks.

Antoni B

  • Loose microcystic tissue.
  • Adjacent to Antoni A.

Micrographs:

Neurofibroma

General:[8]

  • Composed of Schwann cells, axons, fibrous material.

Appearance/morphology:[8]

  • Plexiform growth pattern - "bag of worms".

Ependymoma

General

  • Called the forgotten glial tumour.

Comes in two flavours:

  1. Ependymoma (not otherwise specified).
  2. Myxopapillary ependymoma.
    • Classically at filum terminale.

Microscopy

Features (classic ependymoma):

  • Cells have a "tadpole-like" morphology.
    • May also be described as ice cream cone-shaped.[9]
  • Rosettes - cells arranged in a pseudoglandular fashion.
  • "Nucleus free zones" - cells arranged around a blood vessel (pseudorosettes) - vessel not seen, only cytoplasm of tumour cells.
    • The nucleus free zone is composed of tumour cell cytoplasm that is adjacent to an unseen blood vessel.
  • Nuclear feature monotonous, i.e. "boring".[10]

Features (myxopapillary ependymoma):

  • Perivascular pseudorosettes:
    • Myxoid material surround blood vessels.
      • Myxoid material surrounded by tumour cells.

Images:


DDx (classic ependymoma):

  • Subependymoma.

Choroid plexus papilloma

Microscopy

Features:

  • Papillae.
  • Psammoma bodies.

Image:

Chordoma

General

  • Location: usually sacrum or clivus.

Microscopic

Features:[11]

  • Architecture: islands of cells surrounded by fibrous tissue.
    • Also described as "lobulated" architecture; may not be apparent.
  • Myxoid background - grey extracellular material, variable amount present.
  • Mixed cell population:
    1. Abundant eosinophilic cytoplasm.
    2. Physaliphorous cells or bubble cells - key feature.
      • Have a very large clear bubble with a sharp border; bubble does not compress nucleus - nucleus may be in bubble.

Image(s):

IHC

Features:

  • S100 +ve.
  • CK +ve.
  • Brachyury +ve.
    • Protein important for axial development, affects notochord development.[12]
    • Brachyury literally means short tail.[13]

Hemangioblastoma

General

Microscopic

Features:[14]

  • Vascular.
  • Polygonal stromal cells with:
    • Hyperchromatic nuclei.
    • Vacuolar cytoplasm.

References

  1. ↑ http://neurosurgery.mgh.harvard.edu/abta/primer.htm
  2. ↑ Rong Y, Durden DL, Van Meir EG, Brat DJ (June 2006). "'Pseudopalisading' necrosis in glioblastoma: a familiar morphologic feature that links vascular pathology, hypoxia, and angiogenesis". J. Neuropathol. Exp. Neurol. 65 (6): 529–39. PMID 16783163.
  3. ↑ http://dictionary.reference.com/browse/palisading
  4. ↑ JLK. 31 May 2010.
  5. ↑ MUN. 9 Mar 2009.
  6. ↑ URL: http://www.emedicine.com/radio/topic481.htm.
  7. ↑ Fontaine D, Vandenbos F, Lebrun C, Paquis V, Frenay M (2008). "[Diagnostic and prognostic values of 1p and 19q deletions in adult gliomas: critical review of the literature and implications in daily clinical practice]" (in French). Rev. Neurol. (Paris) 164 (6-7): 595–604. doi:10.1016/j.neurol.2008.04.002. PMID 18565359.
  8. ↑ 8.0 8.1 8.2 8.3 Wippold FJ, Lubner M, Perrin RJ, Lämmle M, Perry A (October 2007). "Neuropathology for the neuroradiologist: Antoni A and Antoni B tissue patterns". AJNR Am J Neuroradiol 28 (9): 1633–8. doi:10.3174/ajnr.A0682. PMID 17893219. http://www.ajnr.org/cgi/reprint/28/9/1633.
  9. ↑ http://www.pathology.vcu.edu/WirSelfInst/tumor-2.html
  10. ↑ MUN. 6 Oct 2009.
  11. ↑ DCHH P.184.
  12. ↑ URL:http://www.ncbi.nlm.nih.gov/omim/601397. Accessed on: 18 May 2010.
  13. ↑ URL: http://www.jstor.org/pss/86845. Accessed on: 18 May 2010.
  14. ↑ URL: http://emedicine.medscape.com/article/340994-media. Accessed on: 23 June 2010.

External links

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