What to Know About Mast Cell Tumors in Cats

Medically Reviewed by Amy Flowers, DVM on March 08, 2024
3 min read

Mast cell tumors (MCTs) are the second most common skin tumor in cats. Feline mast cell tumors are commonly found in the head, neck, and limbs.  If your cat has cutaneous mast cell tumors, it can recover and lead a normal healthy life after surgery.

A mast cell tumor (MCT) is a tumor that originates from mast cells. Mast cells are found in all the tissues of the body, but they are most numerous in the skin, the respiratory tract, and the digestive tract. Mast cell tumors are particularly common in older cats and Siamese cats. 

Mast cells have several functions in the body, including making histamine. Generally, mast cells are involved in allergic responses, wound healing, tissue remodeling, and non-allergic skin diseases.

MCTs can affect the skin (cutaneous MCTs) or the internal organs (visceral MCTs). Tumors can also be benign (noncancerous) or malignant (cancerous). Although mast cell tumors in cats are rare, a cat with a history of mast cell tumors may get them again.

Cutaneous mast cell tumors are abnormal tissue growths on the skin characteristic of cancer and some behave in a more malignant fashion than others.. They are the second most common skin tumors in cats and account for about 20% of feline cutaneous tumors. 

The majority of cutaneous mast cell tumors in cats tend to occur on the head (about 50%), followed by the trunk (about 35%) and the limbs (about 12%). 

Mast cell tumors appear on cats as small, firm, hairless raised bumps or lumps on the skin. Your cat may or may not have some itching in those areas, depending on how it reacts to histamine production in its body. If your cat itches and chews the tumor during these flare-ups, it could injure itself.

If the tumor is malignant, your cat may have a decreased appetite, leading to weight loss. Your cat may also vomit or become ill due to the production of inflammatory chemicals.

How Are Mast Cell Tumors in Cats Diagnosed?

Your vet may carry out a series of tests and examinations to determine if your cat has a mast cell tumor. This includes microscopic examination of any potential tumor. Your vet can help determine the type or origin of the tumor, as well as how developed any potentially cancerous tumor may be. Your vet will use this information to guide you in making an informed decision about your cat's health.

Since mast cell tumors affect every cat differently, your vet will tailor the treatment options to your cat's specific case.

Since chemotherapy (treatment with drugs) and radiation therapy have major side effects, the most common treatment for mast cell tumors in cats is surgery. However, if your cat can't undergo surgery, the location of the tumor makes surgery too risky, or your cat undergoes surgery and has some tumors left behind, your vet may recommend alternative treatment options.

If your cat has surgery, they’ll need to take antibiotics, antihistamines, pain medications, or other prescriptions at home.

Many natural remedies promise to cure or manage mast cell tumors in cats. However, these claims may not be clinically backed. Discuss it with your vet before starting your cat on any natural remedy. 

If your cat has cutaneous mast cell tumors, they will likely do very well after surgery, because cutaneous mast cell tumors are very unlikely to return once surgically removed. If the tumors do return, it will usually be within the first six months after surgery.

Cats with visceral (internal) mast cell tumors, on the other hand, live for an average of one year after treatment with surgery, chemotherapy, and other supportive care.

Early detection and appropriate treatment of mast cell tumors significantly improves outcomes.

Prevent your cat from scratching, rubbing, biting, or licking any tumors on their skin. This will reduce the risk of inflammation, itching, ulceration, bleeding, and infection. If your cat does injure themselves in the area near a tumor, be sure to keep that area clean. Your vet may recommend an Elizabethan collar (E-collar or cone) to keep your cat from hurting themselves.