CSF cytopathology

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CSF cytopathology is a subset of CNS cytopathology, which is a subset of cytopathology.

This article deal only with cerebrospinal fluid (CSF) cytopathology. An introduction to cytopathology is in the cytopathology article.

All CSF specimens get triaged at UHN as:

  1. They are small specimens ~ usually 1-10 ml.
  2. The procedure to obtain them is non-trivial, i.e. not pleasant for the patient and not risk free.
  3. Lymphoma is a common malignancy of malignancies found in the CSF.

All CSF specimens are stat.

Cerebrospinal fluid

Normal

  • Paucicellular.

Gobs of anuclear material:

  • Protein vs. white mater.

Bark-like flaky material:

  • Contaminant.

Fluffy/smudged large cells (~2-3x RBC dia.) with an indistinct nucleus:

  • Degenerated white cells.
    • Should prompt a comment about "degeneration", if the population is dominant.

Routine processing

  • Cytospin - if no abnormality at triage.
    • The cellularity of the cytospin will appear to be increased (artifact).

Acute bacterial meningitis

  • Neutrophils;[1] none should be present normally.[2]
    • If the tap is traumatic (i.e. fibrin is present) the finding may be uninterpretable.

Viral meningitis

Main article: Meningitis

Cytology

  • Polymorphous population of lymphocytes.[1]

Mollaret's meningitis

General

  • Rare aseptic meningitis.
  • Suspected to be caused by HSV1 and HSV2.[3]

Clinical:

  • Recurrent meningismus, headache, +/-fever.[3]

Cytology

Features:

  • Mollaret cells - described as monocytoid cells[1] (look like monocytes[4] - but do not phagocytose), and large endothelial cells.[3]
    • Features - large cells with: abundant cytoplasm, footprint-shaped" nucleus.
    • Mollaret cells not pathognomonic.[3]
  • Mixed population of inflammatory cells[1] (PMNs, monocytes, plasma cells, lymphocytes); usually lymphocyte predominant.[3]

Image:

CNS lymphoma

Histology:[1]

  • Too many cells - key feature.
    • Not diagnostic... but should raise suspicion.
  • Single cells (as typical of lymphoma/leukemia).
  • Large lymphocytes - >2x RBC diameter.
  • +/-Nuclear atypia.
    • Radial segmentation - a completely cleaved nucleus/quasi-binucleation.

Notes:

  • Massive karyorrhexis (nuclear fragmentation) is suggestive of lymphoma[1] - not common.

CNS fungal infections

  • Cryptococcus is the most common.[5]

Cryptococcosis

Main article: Cryptococcosis
  • AKA cryptococcus infection

General

  • Usu. immunocompromised host.

Microscopic

Microscopic appearance:

  • Yeast:[5]
    • Round/ovoid 5-15 micrometres.
    • Thick mucopolysacchardie capsule + refractile centre.
      • "Target-like" shape/"bull's eye" appearance.
    • "Tear drop-shapped" budding pattern (useful to differentiate from Blastomyces, Histoplasma).

Images:

Non-lymphoid neoplasm

  • Non-lymphoid neoplasms are rarely found in the CSF.

Astrocytoma:

  • May vaguely resemble a neuroendocrine tumour:
    • Small cell clusters.
    • Nuclear moulding.
    • Cells somewhat larger than small cell carcinoma.
    • Scant cytoplasm.

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Lefkowitch, Jay H. (2006). Anatomic Pathology Board Review (1st ed.). Saunders. pp. 681 (Q25). ISBN 978-1416025887.
  2. ↑ MUN. 4 November 2010.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 http://emedicine.medscape.com/article/1169489-overview
  4. ↑ http://www.mondofacto.com/facts/dictionary?monocytoid+cell
  5. ↑ 5.0 5.1 Lefkowitch, Jay H. (2006). Anatomic Pathology Board Review (1st ed.). Saunders. pp. 682. ISBN 978-1416025887.
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