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What is Mast Cell Tumor?

Mast cells are present in most tissues and can form an important part of your cat’s immune system. In the case of a mast cell tumor, the healthy cell begins to mutate and take on an abnormal shape and can grow and reproduce, invading other nearby tissue. Mast cell tumors can be benign (non-cancerous) or malignant (cancerous) and have varying degrees or ratings. Mast cell tumors have a tendency to affect older cats over 10 years of age and are especially prevalent in Siamese cat breeds. Mast cell tumors are also sometimes referred to as mastocytomas.

Mast Cell Tumor Average Cost

From 526 quotes ranging from $3,000 - $8,000

Average Cost

$6,000

Symptoms of Mast Cell Tumor in Cats

Like many tumors, mast cell tumors will begin with raised bumps or growths with an escalation of symptoms depending on the severity of the condition and whether the tumor is cancerous. Symptoms include:

  • Raised growth or bump
  • Loss of hair in area of bump
  • Redness or irritation of bump
  • Can be located on or below the skin
  • Typically located on the trunk or body but can occur in other areas
  • Ulceration may occur if your cat irritates the mass or in severe cases of cancerous tumor
  • If a tumor metastasizes, or spreads, systemic symptoms such as lethargy, general sickness, or loss of appetite may occur.
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Causes of Mast Cell Tumor in Cats

The cause of mast cell tumors, as is the case with most types of tumors and cancers, is unknown. Mast cell tumors form and spread when an unnatural mutation occurs within the healthy mast cell. 

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Diagnosis of Mast Cell Tumor in Cats

Diagnosis of mast cell tumor in your cat will begin with a thorough physical exam. Your vet will examine the suspected tumor and will search your cat for any additional tumors located on other parts of the body. You should provide a thorough medical and physical history of your cat to your veterinarian. It will be especially important to note the approximate date of first appearance of the tumor and the amount of growth since that time. If the tumor has changed in size rapidly, including reduction, this will be especially important for helping your vet determine how aggressive the tumor is.

Your vet will next conduct a biopsy of the tumor. This will often be done using a technique called fine needle aspiration. During this procedure, a needle is inserted into the tumor and is used to withdraw a small number of cells. Your vet will then view those cells under a microscope to determine if there are any cellular changes in appearance, also called differentiation, that could indicate the tumor is cancerous.

If your vet determines the tumor is malignant, he or she may order additional tests to determine whether or not the cancer has spread to any other organs. These tests may include a complete blood panel, fine needle aspiration of the lymph nodes closest to the tumor, and x-rays of the head and chest.

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Treatment of Mast Cell Tumor in Cats

The preferred treatment for mast cell tumors in cats is surgical removal of the tumor. Prior to any surgery, your veterinarian will order a full blood panel in order to ensure there are no additional conditions that would make surgery extra risky for your cat. In preparation of surgery, your cat will be placed under anesthesia. Your veterinarian will attempt to remove as much of the tumor as possible. In the case of cancerous mass cell tumors, your vet will attempt to gain clean margins. This means they may have to remove extra tissue around the edges of the tumor to ensure that all of the cancerous cells have been removed.

In cases which cancer has spread, your veterinarian may opt to treat your cat with chemotherapy. During chemotherapy, strong drugs are administered to your cat. These drugs attack the cancer cells, causing them to shrink or disappear. Chemotherapy is usually administered in several treatments over a number of months and can have serious side effects. These side effects may be lessened by additional medications prescribed by your veterinarian.

In the case of benign mast cell tumors that have become inflamed, your vet may choose an alternative form of treatment involving anti-inflammatory drugs. Anti-inflammatory drugs will reduce the size and slow the spread of the tumor. This will be the treatment of choice for older cats who may be high-risk surgical candidates.

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Recovery of Mast Cell Tumor in Cats

While they may appear frightening, mast cell tumors actually have a good prognosis for recovery. With surgical removal of the tumor, most cats will recover and lead normal healthy lives. As with any surgical procedure, you will need to carefully follow your vet’s post-operative instructions for wound care. You will also need to keep your cat quiet for several days following surgery.

While they can spread, cancerous mast cell tumors do not have a tendency to metastasize or move to other parts of the body. Your cat will need routine follow-up appointments with your veterinarian and careful monitoring on the owner’s part to ensure that tumors do not return or appear in other areas.

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Mast Cell Tumor Average Cost

From 526 quotes ranging from $3,000 - $8,000

Average Cost

$6,000

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Mast Cell Tumor Questions and Advice from Veterinary Professionals

Need pet health advice? Ask a vet

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Ask a Vet

dog-name-icon

Jack

dog-breed-icon

tabby

dog-age-icon

11 Years

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Moderate severity

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Moderate severity

Has Symptoms

Vomiting, Swelling, Itching

My cat Jack has a mast cell tumor on the right side of his neck and it seems to swell every so often and then go down. I’m concerned because the last time it swelled I had to rush him to the emergency vet because he started panting so bad. That night he was diagnosed with diabetes for the first time but they thought it was his mast cell tumor swelling so much that sent him into almost a panic state. I’ve had him for about a year and a half so I don’t know his whole health history. He’s 11 years old and the best kitty ever! His last flare up was in April when we went to the emergency vet. I took him to a new vet after that visit and they put him on insulin twice a day, along with 5mg of Zyrtec. They also said I could use Claritin or Benadryl but I know how Benadryl makes me feel, even the non drowsy, so I choose Zyrtec. His tumor started swelling again this morning and now is very large and hard. Both vets said surgery would be very risky due to its location. Is there anything I can do to help with the swelling now? Of course it always happens over the weekend. Should I increase his dosage of Zyrtec or try Benadryl instead? Thank you!

Aug. 12, 2018

Jack's Owner

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3320 Recommendations

Don’t increase the dosage of Zyrtec (cetirizine) as it isn’t approved for use in cats and I have no toxicology data for it apart from standard dosing at 5mg per day; the use of another antihistamine may be useful but since both Zyrtec and Benadryl isn’t approved for use in cats I don’t know of any issues if they are used together. You should keep an eye on Jack for the meantime, but if there are sign of respiratory issues or pain you should go to the emergency clinic to be on the safe side. Regards Dr Callum Turner DVM

Aug. 12, 2018

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Tristan

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Ocicat

dog-age-icon

15 Years

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Moderate severity

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1 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Hard Nodules On Head And Neck

My fifteen-and-a-half-year-old Ocicat has multiple tumors on his head and neck, and I’m wondering whether it’s worth the risk (and trauma) of surgery to have them removed at this point in his life. They’re probably mast-cell tumors (we’ve removed several of these over the past five years), but these new ones haven’t been tested. He’s running on one kidney, sometimes has a heart arrhythmia, and has some sort of digestive disorder (maybe IBD, but he hasn’t been biopsied) that seems to be well controlled with 5 mg of prednisolone and 5 mg of famotidine every-other day. He’s eating well, isn’t losing weight, and is quite lively. Do you think it’s worth removing the tumors or would you advise just letting them be at this stage of his life?

Aug. 10, 2018

Tristan's Owner


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Dr. Michele K. DVM

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1611 Recommendations

That is a very difficult decision to make, sadly. It seems that Tristan is stable and doing well for now, and with so many risk factors for surgery, I would be hesitant to do that surgery. At some point, something ends all of our lives, and it becomes a balance of risk vs benefit. I can't comment on him specifically without examining him, but I would be very cautious having surgery, given what you are describing.

Aug. 10, 2018

Thank you so much for your kind--and swift--response to my question about Tristan! It can be really hard to know when to stop medical interventions on a beloved older cat, so I'm very grateful for your insight and thoughtful advice.

Aug. 10, 2018

Tristan's Owner

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Phoenix

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Mainecoo

dog-age-icon

1 Year

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Mild severity

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pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Mild severity

Has Symptoms

Lump

My 1 1/2 year old cat had a mast cell tumor removed from his chin. It came back high grade with a miotic index of 11. We started him on chemotherapy two days ago. We are also giving him mushroom immune gold to support his immune system. They got all of the tumor with surgery and the margins are clean. Ultrasound shows a normal size spleen and his lymph nodes are not enlarged. He is also on prednisone, benedryl and Pepsid. Do you think this will take care of it? What kind of side effects can I expect from the chemo

July 20, 2018

Phoenix's Owner

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Dr. Michele K. DVM

recommendation-ribbon

1611 Recommendations

Without knowing what chemotherapy medications Phoenix is taking, I can't comment on what the side effects might be, but your veterinarian can discuss that with you in more detail and let you know what to watch for. As far as his surgery, that sounds like the best case scenario at this point for that mass, and hopefully chemotherapy will keep others from occurring.

July 20, 2018

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Henry

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Tuxedo cat

dog-age-icon

7 Years

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Serious severity

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Serious severity

Has Symptoms

Small Lump On Left Ear.

our 7 year old cat had a small bump on his ear. He has few others in the past that have gone away. This time the vet aspirated it and thought there were malignant cells. She sent the sample to a pathologist who agreed. She wants to remove the ear ASAP. Should I go to a vet who specializes in cancer in cats. Are there alternative?

July 15, 2018

Henry's Owner

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recommendation-ribbon

3320 Recommendations

A simple pinnectomy would remove the tumour and any surrounding tissue; the whole ear can be sent then for histopathology for more information. Your general Veterinarian should be able to handle this themselves, but if you feel more comfortable go to an Oncologist for surgery and follow up. Regards Dr Callum Turner DVM https://wagwalking.com/cat/treatment/complete-pinnectomy

July 16, 2018

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Charlie

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Domestic long hair

dog-age-icon

12 Years

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Fair severity

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pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Fair severity

Has Symptoms

None

Last year my 11 year old cat had 3 benign mast cell tumors removed. They were a little bigger than a nickel. About a year later I found 5 very small tumors, pea sized. The vet found 7 more even smaller. All have been removed, all benign. He is now taking 1/2 a benedryl twice a day. I expect there will be more tumors. My question is should I keep having them removed as my cat gets older? The cost is becoming prohibitive and it's pretty traumatic for the cat as well.

July 6, 2018

Charlie's Owner

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recommendation-ribbon

3320 Recommendations

Typically surgical removal of mast cells is the treatment of choice, but in many cases a wait and see approach may be taken; problems only occur if they grow too large or get damaged and infected. You should keep an eye on their formation and discuss with your Veterinarian about your options. Regards Dr Callum Turner DVM

July 7, 2018

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Zed

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DOMESTIC

dog-age-icon

12 Years

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Mild severity

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pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Mild severity

Has Symptoms

Lethargy

Wow, I am so happy to have found this site! My 12 year old Zed had 2 MCTs removed 2 years ago - wide margins, "typed 1" and no other symptoms common with internal disease. He now has approx 5 more sites of varying sizes. I would like to know if these should all be removed or if I can put him on an antihistamine or anything else to stop the growth/reduce symptoms. What food contents are best for cats with MCTs? I know high protein, no carbs, but what does this mean specifically? I see that treating with prilosec is recommended in these cases, but what about the recent recall for cancer causality in humans? Finally, are there any symptoms that specifically correlate with internal spread of MCT and can a patient with internal MCT be a-symptomatic. We live in a rural area and our vet is great, but we are somewhat resource limited. Thanks so much!

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Potato

dog-breed-icon

Black medium haired mix

dog-age-icon

3 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Mild severity

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pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Mild severity

Has Symptoms

Mast Cell Tumor

About one year ago, we found a tick on my cats left jawline. A couple months later, noticed a small lump appearing on or near the site where the tick was. It was just white and hairless. Pretty tough to find also. I brought him in immediately and we tried to aspirate it, but couldn’t get any sampling after multiple tries. After that point, it started to shrink in size. About 6 months later, my vet looked at again and said she wasn’t worried about it and didn’t aspirate. Now it’s been about a year since we first saw it, and it feels like it’s gotten back to its original size and easier to find. I brought him in and they aspirated it and found it to be a mast cell tumor. I’m obviously extremely worried about this because it’s been a year now. Has it been too late? Is there anyway to know the grade of this? I have to wait to do blood work this week, and then in three weeks, he’s having it removed. He’s not shown any changes to his appetite or energy level all year. And the tumor has been healing quickly from the aspiration we just did the other day. He’s only 3 years old and very healthy, I just can’t believe this has happened and I am so worried if it’s metastized at this point.

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Maya

dog-breed-icon

mixed

dog-age-icon

6 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Fair severity

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pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Fair severity

Has Symptoms

None

Hi everyone My name is Carol and I'm from Brazil. My 6 year old cat, Maya, was diagnosed yesterday with a third cutaneous mast cell tumor. The first tumor was removed from the right paw in December 2017 (when she lost a digit due to surgical margins), the second was removed from the right shoulder region in March 2019 and now the third is located in the region between the left eye and ear (closer to the ear). The first 2 surgeries were initially curative, since the margins were free according to the biopsy results. I have read a lot about it and I am very distressed. I would like to know if the fact that lesions continue to appear over time is normal and could be considered metastasis. And I wonder also if there is anything I could give her in terms of medications or supplements that could help lower the chance of new tumors to appear (of course all of this would be discussed with her vets before). Please, if any professional can clarify my doubts, I will be very grateful because I am desperate. This condition of her affects me very much emotionally, not to mention that I don't have all the money a surgery and associated procedures require to spend every few months (I'm currently unemployed, inclusive). Please help me with as much information as you can. Thank you!

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Lola

dog-breed-icon

domestic short hair

dog-age-icon

10 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

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pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Vomiting, Constipation

Hello all, I was devastated by the news that my Lola has a mast cell tumor in her spleen the doctor who performed the ultrasound and fine needle aspiration told me it’s systemic mastocytosis. They also found that liver was slightly enlarged and intestines thickened. We will be going to an oncologist tomorrow to see what our options are however I find limited to no information on it and would love some advice. Her symptoms initially led us to believe she had CKD (vomiting, frequent urination, high SDMA) however everytime they would do blood it would show up as high phosphorus and the straighten itself out. Long story short she had been vomiting regularly we got her vomiting under control using Prilosec and getting her thyroid straightened out so we didn’t think anything of it and we finally did the ultrasound and BAM :( she also has this weird symptom that sometimes she’ll have like 24-48 hour episode of squinting and discharge coming from her eyes. Docs couldn’t tell me what it was and I couldn’t figure it out. Hoping the oncologist tomorrow might have some more insight. Just want to give my baby comfort and quality for however long I have left with her.

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Digit

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back tuxedo cat

dog-age-icon

16 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Anemia And Weight Loss

My 16 year old female cat, Digit, was just diagnosed (by a specialist) with mast cell tumor of the spleen. Digit has been losing weight and is a little anemic but still continues to want to eat regularly...even wants more more wet food and seems to be hungry all the time. Because she is 16 years old my regular vet said that even though Digit is still in good health the surgery may kill her. Your thoughts?

Mast Cell Tumor Average Cost

From 526 quotes ranging from $3,000 - $8,000

Average Cost

$6,000

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