Page 29 - Differential Diagnosis in Small Animal Cytology, The Skin and Subcutis

VetBooks.ir 3 Guidelines to Cytology
Smear Examination

A correct approach to slide examination is considered crucial for an appropriate interpretation
of cytological samples and to reduce the chances of missing important details. A poor and super-
ficial examination technique may lead to a wrong diagnosis and incorrect clinical decisions.
Therefore, cytological evaluation should be performed with a systematic approach, conducted in
the same way each time a slide is examined.
The overall accuracy of cytology testing greatly depends on the quality of the specimen,
including the cellularity of the sample, the preservation of the cells and the quality of the staining.

Factors that can have an impact on the quality of the cytological specimens and may result
in a non-diagnostic sample
• Inadequate sampling or smearing technique.
• Excessive suction.
• Traumatic smearing.
• Haemorrhagic lesions.
• Aspiration from a necrotic centre.
• Poorly exfoliative lesions (e.g. lesions rich in collagen stroma).
• Staining features.
• Insufficient staining due to incorrect procedure or old stains.
• Sample contamination with lubricant or ultrasound gel.
• Exposure of the unfixed slides to formalin fumes.

When the aspirates are acellular or mostly contain disrupted cells without a clear and distinct
cytoplasm (e.g. bare/naked nuclei), a cytological interpretation may not be possible and re-sampling
should be recommended. Similarly, if the sample is adequately cellular and the cells are intact
but the staining quality is poor, a cytological diagnosis might be precluded.

16 © Francesco Cian and Paola Monti 2019. Differential Diagnosis in Small Animal Cytology
(F. Cian and P. Monti)