My dog had mast cell tumor surgery. What if margins aren't clean?

I'm so sorry poor Barney had to have surgery! It can be common with mast cell tumors removed from the limbs to not have clean margins because there isn't a lot of tissue to work with in that area. This doesn't necessarily mean the tumor will return but it does increase the chances. If the pathologist noted that no mitosis was seen this means they did not see any cells in the active stage of dividing. With very malignant tumors there will generally be a lot of mitosis or cell division seen. I hope Barney recovers from his surgery well and that this is the only one he needs!

I’m sorry to hear about Tsunami’s diagnosis. MCTs are quite common in dogs, and unfortunately due to the cell distribution around the primary tumor, incomplete margins are common. If you want to be confident you’re pursuing the best options for the best prognosis, I recommend asking your vet for an oncologist referral. A veterinary oncologist will be the best specialist to be able to present all the options and their given pros & cons, and they have access to chemo medications that most primary vets don’t carry. If you choose not to pursue referral, then I recommend reaching out to your vet again to discuss the next step. If this were my case, I would probably recommend sampling Tsunami’s lymph nodes with a needle to look for evidence of regional metastasis, and based on those findings discuss if a second surgery is appropriate. Hope this helps!

It is great news that the tumor removed had clean margins! This means it is much less likely to come back in the future. Tumors are graded on how many abnormal or cancer-type cells are seen when examining the biopsy under a microscope. Grading can be different for all the tumor types, but for most tumors a grade of 2 is only moderate in severity. This means the tumor has a chance of spreading but it is not very likely. Your vet probably recommended you visit an l oncologist just to be thorough. Oncologist have a lot more up-to-date information on cancer treatments and staging then regular practitioners do. The oncologist may recommend you do chemo to be on the safe side or they may recommend that you don't need to take any further steps. I hope this helps. Thanks for using Petco Pet Education Center, formerly Petcoach. Best of luck.

Thank you for submitting your question regarding Twix. Mast cell tumors are one of the most common forms of skin cancer in dogs. If the margins were clean (meaning all of the cancerous cells were removed), then the mass should not recur. However, mast cell tumors are one of the more unpredictable types of cancer. I recommend closely monitoring his incision site at home for any regrowth. It is best to see his veterinarian at least every 6 months for an examination. At this visit a thorough physical examination will be performed to search for other masses or enlarged lymph nodes. Blood work should be monitored as well. Unfortunately, there is nothing that you or your veterinarian can do to prevent further growths from forming. If any new new growth is observed, a fine needle aspirate should be performed as soon as possible to determine the type of mass. If it requires surgical removal, it is always best to have it done while small for the best chance of achieving clean margins. I hope this information helps!

Skin grafting can be tricky and there is a high risk that the graft would fail, especially when it is applied to an area where there previously was cancer. Mast cell tumors require 2 to 3cm margins and on the leg, many times, this is unachievable. Amputation is likely the best option. If you want to try and save the leg, I would discuss this further with a soft tissue surgeon and then an oncologist. I hope this helps guide you in the right direction. Please feel free to contact me with any further questions or concerns and I would be more than happy to help you further.

Yes. If the margins were "dirty", then there is the likelihood of tumor regrowth. Another surgery with wider margins may be indicated. If the tumor is malignant, a consult with an veterinary oncologist for follow up treatment is strongly recommended.

Hello, thank you for your question about Zeus. If the lumps/masses were removed with relatively good margins, meaning that your veterinarian was fairly confident they removed all portions of the tumor, and the mast cell tumor was low grade no additional treatment is required other than close monitoring for recurrence in these areas. Although not as common with low grade mast cell tumors, you could elect to look for any evidence of metastasis, or travel of the tumors. This would likely include chest x-rays and an abdominal ultrasound. However, I believe it is also appropriate to continue monitoring Zeus. Hope this helps, good luck!