EcPV2 DNA in equine papillomas and in situ and invasive squamous cell carcinomas supports papillomavirus etiology.
Authors: Lange C E, Tobler K, Lehner A, Grest P, Welle M M, Schwarzwald C C, Favrot C
Journal: Veterinary pathology
Summary
# Editorial Summary Equine penile papillomas and squamous cell carcinomas (both in situ and invasive forms) are believed to represent a disease continuum driven by papillomavirus infection, though definitive aetiological evidence has been lacking until now. Lange and colleagues investigated this hypothesis by extracting DNA from tissue samples of 24 horses with characteristic penile papillomas or carcinomas, alongside 11 control horses with unrelated penile conditions, then used polymerase chain reaction to detect equine papillomavirus 2 (EcPV2) and in situ hybridization to localise viral DNA within tissues. All papilloma and squamous cell carcinoma samples tested positive for EcPV2 DNA variants, with viral nucleic acid concentrated within koilocyte nuclei, whereas only 6 of 11 control samples contained detectable virus, supporting a causal relationship rather than coincidental colonisation. These findings establish EcPV2 as the aetiological agent of equine penile neoplastic disease and have significant implications for practitioners: diagnosis can now be confirmed via PCR testing, and understanding the papillomavirus continuum may guide management decisions regarding monitoring, treatment timing, and potential future preventive strategies such as vaccination.
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Practical Takeaways
- •Equine penile papillomas and squamous cell carcinomas are papillomavirus-induced lesions representing a disease continuum—recognition of early papillomas may allow intervention before malignant progression
- •EcPV2 testing can confirm diagnosis of suspicious penile lesions, but positive results in control lesions suggest viral presence alone may not be pathogenic without concurrent histologic changes
- •Stallions with penile papillomas should be monitored closely for malignant transformation, and affected animals may warrant breeding restrictions if viral transmission risk is a concern
Key Findings
- •EcPV2 DNA detected in 100% of papilloma and squamous cell carcinoma samples (24/24 cases)
- •EcPV2 DNA also found in 55% of control lesions (6/11), suggesting possible latent or incidental infection
- •In situ hybridization confirmed EcPV2 nucleic acid localized to koilocyte nuclei, supporting direct viral involvement
- •Data support papillomavirus etiology for the continuum of penile lesions from papillomas to invasive carcinoma