CSF cytopathology

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

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

In many institutions, CSF specimens get triaged/rapidly assessed 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.

The findings from CSF specimens are usually needed speedily;[1] thus, in many institutions these specimens are stat.

Cerebrospinal fluid

Normal

  • Paucicellular.
  • <12/3 cells
  • protein is around 15-40 mg/dl

Gobs of anuclear material:

  • Protein vs. white matter.
  • Ocassionally arachnoid cap cell-

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).

Images

Hemorrhage

  • Xanthochromatous specimen
    • Can be artificial -> due punctuation injuries or rifampin medication.[2]
    • Can be seen in newborn -> due to increased bilirubin levels.
    • Best seen when looking from top through the tube. [3]
    • pink (free hemoglobin directly after bleeding) to yellow (bilirubin after one day).


Cytology

  • Mostly RBC.
  • Neutrophils can be increased.
  • +/-Erythro- and Siderophages (usu. after 3-4d).


Acute bacterial meningitis

Cytology

  • Neutrophils - none should be present normally.[4][5]
    • If the tap is traumatic (i.e. fibrin is present) the finding may be uninterpretable.
    • Neutrophils may be present in early exsudative phase of viral meningitis.
  • Cell count usually above 1000/µl.

DDx:

  • TBC
  • Fungal meningitis

Viral meningitis

General

  • Positive viral culture.
    • HSV
    • CMV
    • Enterovirus
    • HIV

Cytology

  • Pleocytosis (usu. 10-1000 cells/µl).
  • Polymorphous population of lymphocytes.[4]
  • Activated lymphocytes.
  • Plasma cells (sometimes bi- and multinuclear).
  • Occ. mitoses.
  • Activated (vacuolated) monocytes.

Mollaret's meningitis

General

  • Rare aseptic meningitis.
  • Suspected to be caused by HSV1 and HSV2.[6]

Clinical:

  • Recurrent meningismus, headache, +/-fever.[6]

Cytology

Features:

  • Mollaret cells - described as monocytoid cells[4] (look like monocytes[7] - but do not phagocytose), and large endothelial cells.[6]
    • Features - large cells with: abundant cytoplasm, footprint-shaped" nucleus.
    • Mollaret cells not pathognomonic.[6]
  • Mixed population of inflammatory cells[4] (PMNs, monocytes, plasma cells, lymphocytes); usually lymphocyte predominant.[6]

Image:

Meningeosis neoplastica

CNS lymphoma

Histology:[4]

  • 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[4] - not common.

Meningeal carcinomatosis (Meningeosis carcinomatosa)

Histology:

  • abnormal cell size / giant multinuclear cells.
  • unusual nuclear/cytoplasm ratio.
  • hyperchromatic nuclei.
  • prominent nucleoli.
  • atypical mitoses.
  • cell clustering.

Notes:

  • cell count can be normal.
  • accompanied by granulocytes and monocytes.

Non-lymphoid, non-epithelial neoplasm

  • Non-lymphoid, non-epithelial neoplasms are rarely found in the CSF.
  • Ependymomas and medulloblastomas have a higher rate of dissemination than other primary brain tumors.

Meningeosis gliomatosa (Astrocytoma/Glioblastoma):

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

CNS fungal infections

  • Cryptococcus is the most common.[8]

Cryptococcosis

  • AKA cryptococcus infection

General

  • Usu. immunocompromised host.

Microscopic

Microscopic appearance:

  • Yeast:[8]
    • 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:

See also

References

  1. Hilborne L, Lee H, Cathcart P (June 1996). "STAT testing? A guideline for meeting clinician turnaround time requirements. Practice parameter". Am. J. Clin. Pathol. 105 (6): 671–5. doi:10.1093/ajcp/105.6.671. PMID 8659440.
  2. Liggett, SB.; Berger, JR.; Hush, J. (Aug 1982). "Cerebrospinal fluid xanthochromia with rifampin.". Ann Neurol 12 (2): 228-9. doi:10.1002/ana.410120240. PMID 7125611.
  3. Bremer, HL. (May 1985). "Identification of xanthochromia.". JAMA 253 (17): 2496. PMID 3981778.
  4. 4.0 4.1 4.2 4.3 4.4 4.5 Lefkowitch, Jay H. (2006). Anatomic Pathology Board Review (1st ed.). Saunders. pp. 681 (Q25). ISBN 978-1416025887.
  5. MUN. 4 November 2010.
  6. 6.0 6.1 6.2 6.3 6.4 http://emedicine.medscape.com/article/1169489-overview
  7. http://www.mondofacto.com/facts/dictionary?monocytoid+cell
  8. 8.0 8.1 Lefkowitch, Jay H. (2006). Anatomic Pathology Board Review (1st ed.). Saunders. pp. 682. ISBN 978-1416025887.