Haine et al: Incomplete histological margins following planned narrow excision of canine appendicular soft tissue sarcomas and mast cell tumors, using the residual tumor classification scheme
Veterinary Surgery 7, 2022

🔍 Key Findings

• Fewer R1 margins (tumor on ink) were achieved in mast cell tumors (MCTs) when using 6–10 mm lateral margins versus 0–5 mm (7% vs. 55%; _P_ = .049).
• For soft tissue sarcomas (STSs), no benefit was seen in margin completeness between 0–5 mm vs. 6–10 mm lateral margins (41% vs. 43% R1).
• Overall R1 rates were 26% for MCTs and 42% for STSs following PNE.
• R scheme (“tumor on ink” = R1) had better interobserver agreement (83%) compared to ≤1 mm margin criteria (68% agreement).
• Complication rate was moderate (26%), but no surgeries required revision.
• Local recurrence/metastasis occurred in 14% of dogs, with 60% of those having R1 margins.
• Adjunctive therapy was considered clinically indicated in 46% of 0–5 mm margin cases vs. 24% of 6–10 mm cases.
• Histologic grade and tumor size were not predictive of margin completeness.