Evaluation of fixation time using Diff-Quik for staining of canine mast cell tumor aspirates

Dorothy E. Jackson, Kim A. Selting, Melanie S. Spoor, Carolyn J. Henry, Charles E. Wiedmeyer

Research output: Contribution to journalArticlepeer-review


Background: Mast cell tumors are the most common cutaneous tumor in the dog and are often diagnosed via fine-needle aspiration and cytology. Many veterinary practices use Diff-Quik stain for these cases because it is easy to use and provides rapid results. Anecdotal reports suggest that Diff-Quik does not stain mast cell tumor granules well and that increased duration of fixation time can improve staining quality; however, this has not been prospectively evaluated. Objectives: The aim of this study was to determine if varying fixation time would affect the staining quality of mast cell granules using the Diff-Quik stain. The null hypothesis was that there would be no difference in the staining of the granules based on duration of time in the fixation solution. Methods: Fine-needle aspirates of cutaneous mast cell tumors were obtained from 21 dogs and distributed on multiple slides. These slides were then stained in Diff-Quik at varying fixation times (ie, 5 seconds, 30 seconds, 1 minute, 2 minutes). One slide was stained with modified Wright stain as a control. Mast cell staining quality was evaluated either by blinded clinicopathologic review (n = 12) or by computer analysis of photomicrographs (n = 6). Results were compared with histopathologic grade. Results: There was no difference in staining quality among groups. Conclusions: Alteration in fixation time using Diff-Quik does not improve staining characteristics of mast cell tumors.

Original languageEnglish (US)
Pages (from-to)99-102
Number of pages4
JournalVeterinary Clinical Pathology
Issue number1
StatePublished - Mar 2013
Externally publishedYes


  • Aqueous
  • Cytology
  • Granules
  • Stain

ASJC Scopus subject areas

  • General Veterinary


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