Mast cell tumor surgery is commonly performed in general and specialty practice. Oncologists and surgeons want to make evidence-based recommendations about the surgery, but there is sometimes a lack of evidence, or that the available evidence is controversial or conflicting. In this wide-ranging lecture, Laura Selmic will highlight some common controversies and present current evidence about these essential topics in mast cell tumor surgery. She will cover surgical dose, surgical margins, pretreatment, lymph node staging with lymphadenectomy, and mast cell tumor histopathology.

One of the most controversial aspects is surgical margins. Traditional surgical recommendations for mast cell tumors have been wide surgical margins, with 3 cm lateral margins and one fascial plane deep. Recent evidence will be presented that supports good outcomes in dogs with low-grade tumors with smaller lateral surgical margins. Additionally, available evidence will be discussed about the surgical margins of high-grade tumors. Pretreatment of mast cell tumors prior to surgery is performed to decrease the size of the tumor if present in a difficult location or is large. The shrinkage of the tumor may influence surgical margins taken and the pathology results, which will be discussed. Sentinel lymph node studies are being more commonly performed with subsequent lymphadenectomy of the sentinel lymph nodes performed for staging purposes. The role of this in canine mast cell tumor staging is incompletely defined and will be discussed. The final topic will be mast cell tumor histopathology; reporting has been found to be variable specifically with inconsistent or incomplete reporting of surgical margins, additionally what constitutes incomplete surgical margin may vary between pathologists.