What Should I do about my Cat with a Mast Cell Tumor?

Question:
My 8 year old, overweight, cat has a history of a heart murmur and a lump on the top of the long part of her paw. An aspiration biopsy said it was a mast cell tumor. I am very confused by the vet & what I read online as to whether or not this is malignant. So far, I have not had it removed because she has no pain, I do not want to put her through surgery with her history, and it costs $1000. What is the most likely thing to happen- not the worst case scenario? The lump has been there about a month. She has not been ill. I worry about the histamine releases that could happen but how likely is that. She is ALWAYS hungry. I wonder now if that is the stomach acid. Should she be on antihistamines or antacids?

A: Mast cell tumors in cat are less common than in dogs.  Speak with your veterinarian about staging options to determine if there is any risk to your cat.  Surgical resection is recommended for cutaneous mast cell tumors in cats, especially if there are multiple tumors present.

Mast cell tumors can cause a histamine release, either local to the site of the tumor, or systemic.  The concern is that it can trigger an anaphylactic reaction if too much histamine is released.  Although, this is less common in cats.  The tumors can be cutaneous (on the skin) or spread to the organs in the abdomen.  You can speak to your veterinarian about having an abdominal ultrasound performed and chest x rays to make sure there hasn't been any spread. 

Surgery is the treatment of choice for cutaneous masses in cats.  Radiation is another form of treatment that is an option.  One final option is to do nothing.  If another mass forms, then it may be a good idea to have both masses removed.  Many times if the tumor is removed, that's it.  It is not very common to have another form in a cat, although possible. 

Many cats are always hungry.  Unless the tumors have spread to the stomach, there isn't much concern for ulcers.  Speak with your veterinarian to see if your cat needs to be on an antacid or antihistamine.  Dogs are more likely to need these protectants than cats. 

~Dr. Page Wages

Oberlin Animal Hospital