Neuropathology tumours

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The article covers tumours in neuropathology. Tumours are a large part of neuropathology. Cytopathology of CNS tumours is dealt with in the article CNS cytopathology.

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.

Location (most common)

Certain tumours like to hang-out at certain places:[2]

  • Cerebrum:
    • Cortical based - oligodendroglioma.
    • Grey-white junction - metastases.
    • White matter - astrocytoma, glioblastoma.
    • Periventricular - CNS lymphoma.
    • Cystic - ganglioglioma, pilocytic astrocytoma, pleomorphic xanthoastrocytoma.
  • Cerebellum:
    • Midline/central - medulloblastoma.
    • Cystic lesion - pilocytic astrocytoma (younger individual), hemangioblastoma (older individual).
    • Solid lesion (older individual) - metastasis.
  • Spinal cord:
    • Ependymoma, glioblastoma.
    • Filum terminale - myxopapillary ependymoma, paraganglioma.

Primary vs. secondary

Glial tumours:

  • Cytoplasmic processes - key feature.
    • Best seen at highest magnification - usu. ~1 micrometer.
    • Processes may branch.
  • Ill-defined border/blend with the surrounding brain/.

Astrocytomas

Overview

  • 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).

Microscopic

Features:[3][4]

  • Glial processes - key feature.
    • Thin stringy cytoplasmic processes - best seen at high power in less cellular areas.
  • 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.

Image:

Notes:

  • Glial vs. non-glial tumours:
    • Glial: "blends into brain"/gradual transition to non-tumour brain.
    • Non-glial: no glial processes.

Filum terminale

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

DDx:[5]

  • 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

Features:

  • Rosenthal fibres - key feature.

Images:

DDx (of Rosenthal fibers):[6]

  • 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.[7]

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:[8]

  • Greater chemosensitivity
  • Better prognosis.

Peripheral nerve sheath tumours

A classification:[9]

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

Meningioma

General

  • Common.
  • Extra-axial. (???)
  • Most are benign.
    • May be malignant.
  • May be seen in genetic disorders such as neurofibromatosis.[10]

Microscopic

Features (memory device WTC):

  • Whorled appearance - key feature.
  • Thick-walled blood vessels, usually prominent.
  • Calcification.

Many subtypes exist:

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

Images:

DDx:

  • Cerebral angioid angiopathy. (???)

Notes:

  • May involute into benign sclerotic tissue.[11]

Histomorphologic grading

Grading:[12]

  • Grade 1:
    • Low mitotic rate.
    • Excludes clear cell, chordoid, papillary, and rhabdoid subtypes.
  • Grade 2 (either #1 or #2):
    1. Brain-invasive meningioma.
      • Protrusion of meningioma into brain.
        • Meninogioma with entraped GFAP +ve tissue.
    2. Atypical meningioma (by histomorphology).
      • Intermediate mitotic rate (>= 4 mitoses/10 HPF - for whatever HPF means, see HPFitis.)
      • Three of the following five features:
        1. Sheeting architecture.
        2. High NC ratio clusters; clusters of "lymphocyte-like" cells.
        3. Hypercellularity.
        4. Macronucleoli.
        5. Necrosis not caused by treatment, e.g. radiation or embolization.
  • Grade 3 (either of the following):
    • High mitotic rate (>=20 mitoses/10 HPF - for whatever HPF means, see HPFitis.)
    • "Frank anaplasia"; marked nuclear atypia.

hypercell necrosis, NC ratio, macronuc

IHC

  • EMA +ve.[13]
    • Other CKs usu. -ve.

Schwannoma

General

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

Microscopic

Features:[9]

  • Antoni tissue (type A and type B).
  • Verocay bodies - paucinuclear area surrounded by nuclei.

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:[9]

  • Composed of Schwann cells, axons, fibrous material.

Appearance/morphology:[9]

  • 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

Classic ependymoma

Features:

  • Cells have a "tadpole-like" morphology.
    • May also be described as ice cream cone-shaped.[14]
  • Rosettes - cells arranged in a pseudoglandular fashion.
  • "Nucleus free zones" - cells arranged around a blood vessel (perivascular pseudorosettes); nuclei of cells distant from the blood vessel, i.e. a rim of cytoplasm (from tumour cells) surrounds the blood vessel.

Perivascular pseudorosettes = (tumour) cells arranged around a blood vessel; nuclei of cells distant from the blood vessel, i.e. rim of cytoplasm (from tumour cells) surround blood vessel (nucleus-free zone)

    • The nucleus free zone is composed of tumour cell cytoplasm that is adjacent to an unseen blood vessel.
  • Nuclear feature monotonous, i.e. "boring".[15]
    • There is little variation in size, shape and staining.

Images:

DDx (classic ependymoma):

  • Subependymoma.

Myxopapillary ependymoma

Features:

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

Images:

Choroid plexus papilloma

Microscopy

Features:

  • Papillae.
  • Psammoma bodies.

Image:

Chordoma

General

  • Location: usually sacrum or clivus.

Microscopic

Features:[16]

  • 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.[17]
    • Brachyury literally means short tail.[18]

Hemangioblastoma

General

Microscopic

Features:[19]

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

Images:

Medulloblastoma

General

  • Paediatric population. (???)

Microscopic

Features:[20]

  • Homer-Wright rosettes.

Image:

See also

References

  1. ↑ http://neurosurgery.mgh.harvard.edu/abta/primer.htm
  2. ↑ URL: http://www.msdlatinamerica.com/ebooks/DiagnosticNeuropathologySmears/files/4ce563fb7e8e48fc9ed8b42e296a7747.gif and http://www.msdlatinamerica.com/ebooks/DiagnosticNeuropathologySmears/sid117213.html. Accessed on: 2 November 2010.
  3. ↑ 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.
  4. ↑ http://dictionary.reference.com/browse/palisading
  5. ↑ JLK. 31 May 2010.
  6. ↑ MUN. 9 Mar 2009.
  7. ↑ URL: http://www.emedicine.com/radio/topic481.htm.
  8. ↑ 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.
  9. ↑ 9.0 9.1 9.2 9.3 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.
  10. ↑ URL: http://moon.ouhsc.edu/kfung/jty1/neurotest/Q13-Ans.htm. Accessed on: 26 October 2010.
  11. ↑ URL: http://radiographics.rsna.org/content/23/3/785.long. Accessed on: 3 November 2010.
  12. ↑ Perry, Arie; Brat, Daniel J. (2010). Practical Surgical Neuropathology: A Diagnostic Approach: A Volume in the Pattern Recognition series (1st ed.). Churchill Livingstone. pp. 194. ISBN 978-0443069826.
  13. ↑ Perry, Arie; Brat, Daniel J. (2010). Practical Surgical Neuropathology: A Diagnostic Approach: A Volume in the Pattern Recognition series (1st ed.). Churchill Livingstone. pp. 13. ISBN 978-0443069826.
  14. ↑ http://www.pathology.vcu.edu/WirSelfInst/tumor-2.html
  15. ↑ MUN. 6 Oct 2009.
  16. ↑ Tadrous, Paul.J. Diagnostic Criteria Handbook in Histopathology: A Surgical Pathology Vade Mecum (1st ed.). Wiley. pp. 184. ISBN 978-0470519035.
  17. ↑ URL:http://www.ncbi.nlm.nih.gov/omim/601397. Accessed on: 18 May 2010.
  18. ↑ URL: http://www.jstor.org/pss/86845. Accessed on: 18 May 2010.
  19. ↑ URL: http://emedicine.medscape.com/article/340994-media. Accessed on: 23 June 2010.
  20. ↑ URL: http://moon.ouhsc.edu/kfung/jty1/neurotest/Q93-Ans.htm. Accessed on: 26 October 2010.

External links

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