Mast Cell Tumor in Tripawd

Hi just seeking some advice. Our 7 year old rear amp tripawd was just diagnosed with mast cell tumor on his remaining rear leg. The vet that diagnosed him said she was not confident that she could do the surgery herself because of the vulnerable area near the knee and said we probably need to find a speciality soft tissue surgeon. She also mentioned the Stelfonta route. I have an appointment with a surgeon on Thursday but just wondering if there’s any advice or if anyone has dealt with this before, trying not to spiral but it’s hard. Even before the cytology came back we started him on Quercirtin just in case.