Cross-sectional comparison of superficial swab and fine-needle aspiration: Improving the diagnostic workup of horses with sarcoids.
Authors: Gysens Lien, Martens Ann, Haspeslagh Maarten
Journal: Veterinary journal (London, England : 1997)
Summary
Equine sarcoids require laboratory confirmation for optimal treatment planning, yet the most commonly used diagnostic method—PCR screening of superficial swabs—has significant limitations when lesions remain intact and unbroken. Researchers compared swab samples with fine-needle aspirates (FNA) from 63 confirmed sarcoid lesions across 58 horses to determine whether FNA could provide more reliable BPV detection. Fine-needle aspiration substantially outperformed superficial swabbing, detecting bovine papillomavirus in 98% of cases versus 70% for swabs; the difference was particularly pronounced in non-ulcerated lesions (98% versus 63%), with FNA showing 23–52 percentage points higher sensitivity depending on lesion type. Beyond improved detection rates, FNA samples carried lower risk of contamination from superficial keratinocyte colonisation and were more likely to yield adequate material for analysis. For practitioners, this suggests that switching to FNA as the primary sampling method could eliminate diagnostic uncertainty across all sarcoid presentations, potentially streamlining treatment decisions and reducing the need for repeat sampling when initial swab results prove negative or equivocal.
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Practical Takeaways
- •FNA is a superior diagnostic tool to superficial swabs for confirming sarcoid diagnosis, especially for lesions with intact skin, improving diagnostic consistency in your clinical workup
- •Using FNA instead of swabs will reduce false negatives and the need for repeat sampling, allowing faster treatment decisions and better client communication
- •FNA can be incorporated into routine sarcoid diagnosis protocols to provide more reliable confirmation before committing to treatment, particularly for early-stage or non-ulcerated lesions
Key Findings
- •Fine-needle aspiration (FNA) detected BPV in 98% of sarcoid lesions compared to 70% with superficial swabs (P = 0.0001)
- •FNA detected BPV in 98% of non-ulcerated lesions versus 63% with swabs (P = 0.0001), demonstrating superior performance on intact epithelium
- •FNA demonstrated 23-52% higher sensitivity, negative predictive value, and accuracy compared to superficial swabbing across different lesion types
- •FNA reduces risk of false positives from superficial contamination and latent BPV detection while improving adequacy of sampling