Canis ISSN: 2398-2942

Cytology: fine needle aspirate

Synonym(s): FNA

Contributor(s): William Brewer Jr, Kathleen P Freeman

Overview

  • Microscopic study of cells obtained from skin or internal organs.
  • Cells are smeared or pressed (compression smear), onto a slide and stained, then viewed by light microscopy.
  • Rapid, requires minimal equipment.
  • Direct evaluation of neoplastic/inflammatory changes provided representative sample obtained.

Sampling

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Tests

Methodologies

  • Modified Wright's stain or Giemsa stain: best for inflammatory lesions.
  • Diff-quick stain: can adjust color as blue and yellow components are separate. Poor nuclear detail.
  • Light microscopy: scan at x4 and x10.
  • Use x50 and x100 for fine detail.

Validity

Sensitivity

  • Less sensitive than histopathology because more difficult to obtain representative sample.

Specificity

  • Low compared to histopathology as may miss diagnostic cells.

Technique (intrinsic) limitations

  • Information about tissue architecture cannot be obtained.
  • Requires confirmation by histopathology.

Technician (extrinsic) limitations

  • Difficult to obtain representative sample.
  • Requires some experience to obtain consistently reliable samples.

Result Data

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Further Reading

Publications

Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Dunn J K & Villiers E (1998) General principles of cytological interpretation. In Pract 20, 429-437.
  • Moriello K A & Rosenthal R C (1990) Clinical approach to tumors of the skin and subcutaneous tissues. Vet Clin N Am Small Anim Prac t20(4), 1163-1190.
  • Mills J N (1989) Lymph node cytology. Vet Clin N Am Small Anim Pract 19(4), 697-717.


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