CNS cytopathology
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CNS cytopathology is a subset of neuropathology and cytopathology.
An introduction to cytopathology is in the cytopathology article. Cerebrospinal (CSF) specimens are dealt with in a separate article called CSF cytopathology.
Technique
Smears (really squash preps) are common in neuropathology. Here are some tips for getting a good smear:
- Sampling is key -- choose 3-4 small pieces of tissue from different areas of the tissue (if there are different colours, get some of each)
- Keep pieces small (easier to smear)
- Avoid air drying (place into formal alcohol immediately upon smearing)
Basic approach
| CNS cytology | |||||||||||||||||||||||||||||||||||||||||
| Tumour | Non-tumour | ||||||||||||||||||||||||||||||||||||||||
| Glial | Non-glial | Infectious | Non-infectious | ||||||||||||||||||||||||||||||||||||||
| Glial | Non-glial | |
| Stranding (cytoplasmic) |
thin - cannot be seen at low power (2.5x obj.), true cytoplasmic processes |
thick - can be seen at low power (2.5x obj.), artifact of smearing |
| Edge of cluster | smooth/non-distinct | sharp |
Glial vs non-glial:
- Glial has cytoplasmic processes/cytoplasmic strands (stringy processes) ~ 1 micrometer thick.
- They cannot be seen well at low power.
- Cotton candy-like appearance.
- Images:
Gliosis vs. neoplasm:
- Gliosis - uniform, pink
- Astrocytoma - irregular, coarse clumps of pink fibrillary material
High grade vs. low-grade:
- Markers of high grade glioma:
- Mitoses (can see these in smear)
- Necrosis (can also see in smears)
Notes:
- Crush artifact (in smear preparation) can mimic glial processes.
- Crush artifact vs. real glial processes:
- No glial processes run perpendicular to the direction of smear.
- Glial processes may branch.
- Crushed/elongated nuclei are present in artifactual processes.
- Crush artifact vs. real glial processes:
Meningioma
Most meningiomas smear rather well, the only exception being ones that are densely fibrous.
- Key features of meningioma smears:
- Single cells or small groups of epithelioid cells with distinct cytoplasmic 'flags' (cytoplasm usually abundant)
- Round nuclei with vesicular chromatin and unapparent or small nucleoli
- Visible actin striations / stress filaments in cells (seen as pink straight lines)
Metastatic carcinoma
Typically has a 'cannonball' appearance -- with small, highly cohesive clusters of epithelioid cells.
Main article: Metastasis
Things that don't smear well
Cohesive tumours:
- Neurofibroma.
- Schwannoma.[3]
- Subependymoma
- Abscess (because of fibrous capsule)
- Metastasis.[3]
Things that smear well
Dyscohesive tumours:
- Lymphoma.[3]
- Pituitary adenoma.[3]
- Oligodendroglioma.[3]
- Astrocytoma.
- Normal brain.
See also
References
- ↑ 1.0 1.1 URL: http://www.msdlatinamerica.com/ebooks/DiagnosticNeuropathologySmears/sid117213.html. Accessed on: 2 November 2010.
- ↑ URL: http://moon.ouhsc.edu/kfung/JTY1/NeuroTest/Q92-Ans.htm. Accessed on: 3 November 2010.
- ↑ 3.0 3.1 3.2 3.3 3.4 Weedman Molavi, Diana (2008). The Practice of Surgical Pathology: A Beginner's Guide to the Diagnostic Process (1st ed.). Springer. pp. 252. ISBN 978-0387744858.