Polymerase chain reaction analysis of the surgical margins of equine sarcoids for bovine papilloma virus DNA

OBJECTIVE: To examine apparently normal skin around equine sarcoids for evidence of bovine papilloma virus (BPV) DNA, and to relate this finding to the observed recurrence after surgery. STUDY DESIGN: Prospective study. ANIMALS OR SAMPLE POPULATION: Forty-one equine sarcoids from 19 horses. MATERIALS AND METHODS: The tumors were surgically excised at a measured distance of 8, 12, or 16 mm. Samples from the tumor and of the entire surrounding skin were taken at 4, 8, 12, and 16 mm from the tumor border and analyzed for the presence of BPV DNA using polymerase chain reaction (PCR) amplification. The samples were grouped per examined sarcoid, and a tumor was considered positive at a certain distance as soon as at least one of the samples at that distance was positive. The clinical outcome was recorded for each sarcoid after a minimal follow-up of 6 months. RESULTS: All sarcoids were positive for BPV(1) or BPV(2). The tumor margin was positive at 4, 8, 12, and 16 mm in, respectively, 95%, 73%, 39%, and 33% of the examined sarcoids. Local recurrence was observed in 3 sarcoids on 3 different horses. From survival analysis, there was a greater likelihood for local recurrence when sarcoids had a surgical margin that was positive for BPV DNA. CONCLUSIONS AND CLINICAL RELEVANCE: BPV DNA is often detected in visibly normal skin around sarcoids, and there is a significantly greater probability for local recurrence when the surgical margins are positive for the presence of BPV DNA.