[Written by a Veterinarian] Feline Mast Cell Tumors: Symptoms, Treatment, Prognosis, and Daily Care Tips

Have you ever been worried after finding a "lump" or "redness" on your beloved cat's skin? One possible cause is feline mast cell tumors. While they often occur on the skin, they can also develop in internal organs, and early detection is key to treatment. In this article, a veterinarian will explain in detail about the symptoms, treatment, prognosis, and daily care.

What are feline mast cell tumors?

What kind of tumor is a mast cell tumor?

Mast cell tumors are malignant tumors that develop from mast cells. Mast cells are a type of immune cell that are involved in allergic reactions, among other things. They are found in mucous membranes throughout the body.

When mast cells become malignant, they form tumors on the skin or internal organs. Mast cells contain various substances such as histamine and heparin, and when these are released, they can cause swelling, itching, bleeding, and other symptoms. Mast cell tumors come in two types: "cutaneous" and "visceral."

Differences between cutaneous and visceral types

"Cutaneous type" mast cell tumors develop on the skin, often on the face or ears, but can occur anywhere on the body. Hair loss and itching are the main symptoms. They are often discovered as insect bite-like lesions. They can appear as single lesions or as multiple lesions throughout the body. Feline "cutaneous type" mast cell tumors are generally low-grade and less likely to metastasize.

"Visceral type" mast cell tumors develop as masses within the body, causing symptoms such as loss of appetite and vomiting. "Visceral type" mast cell tumors are prone to metastasis and often have a poor prognosis. Visceral mast cell tumors can also metastasize to the skin, appearing as cutaneous type. I have personally seen one case where systemic skin tumors developed due to metastasis from a mast cell tumor in the spleen.

Age of onset and risk factors

The exact causes and risk factors are not clearly understood. They tend to occur more frequently in middle-aged to older cats.

Symptoms of feline mast cell tumors

Skin symptoms

Cutaneous mast cell tumors are often discovered as small lumps. Over time, symptoms such as itching and hair loss may appear, and the lump and surrounding skin may become red.

Symptoms when they develop in internal organs

Visceral type tumors primarily occur in the spleen and digestive tract. As tumors develop in internal organs, symptoms such as vomiting, diarrhea, and loss of appetite may appear.

Tips for noticing symptoms before they progress

In the cutaneous type, insect bite-like rashes develop. If it's a solitary lesion, it might be overlooked. While insect bites heal quickly, cutaneous mast cell tumors remain as a rash that doesn't go away. If your cat is itching, observe where it's scratching, and if you notice a rash, consult a veterinarian immediately.

Visceral mast cell tumors exhibit symptoms that can also appear with other diseases. It is necessary to routinely monitor your cat's food intake and be aware of changes in appetite or the extent of vomiting.

Treatment and prognosis 

Surgical removal

If a solitary cutaneous mast cell tumor is present, it can sometimes be cured by widely excising the tumor and the surrounding healthy skin. Since mast cell tumor cells infiltrate extensively, it is common to remove the tumor along with 2-3 cm of healthy surrounding skin.

For visceral mast cell tumors in the spleen, surgical removal of the spleen may be performed. However, in visceral cases, metastasis may have occurred, so chemotherapy or other treatments may be used in conjunction with surgery.

Chemotherapy and radiation therapy

For multiple cutaneous mast cell tumors, those that could not be completely removed surgically, or visceral mast cell tumors, chemotherapy or steroids may be used. However, the effectiveness of chemotherapy in cats has not been fully established.

A frequently used treatment for mast cell tumors is molecular targeted drugs, which target proteins and enzymes often found in cancer cells. These drugs are characterized by fewer side effects compared to traditional chemotherapy. They are used for multiple cutaneous mast cell tumors in cats, cases where surgery is difficult, or to suppress metastasis.

Radiation therapy is also used to treat mast cell tumors. It is chosen when the tumor is localized to a specific area. However, there are issues such as limited availability of radiation therapy equipment (found only in facilities like university hospitals), the need for general anesthesia, and high costs.

Presence of metastasis and differences in prognosis

If it's a solitary cutaneous mast cell tumor, surgical excision can lead to a complete cure, resulting in a good prognosis. However, if there are four or more tumors, the survival period is said to be between 1 and 2 years. In the case of visceral type, metastasis occurs quickly, leading to an even shorter life expectancy, often less than 1 year.

Daily care and precautions

Make skin checks a habit

For cutaneous mast cell tumors, early detection of skin lumps is crucial. Especially, regularly check the head, ears, and neck, as lumps often form there.

Tips for care in multi-cat households

Mast cell tumors themselves are not preventable. If there is a lump on the skin, licking it can worsen the condition. Mast cell tumor cells contain chemicals such as histamine and heparin, which are released when stimulated. These chemicals can intensify itching or make bleeding more likely.

Additionally, some substances can cause gastrointestinal bleeding or promote vasodilation, leading to a drop in blood pressure and potentially shock. Therefore, it's important to avoid irritating the area.

Summary | Facing feline mast cell tumors

Early detection is crucial for mast cell tumors. If the cutaneous type is treated early, a complete cure is possible. Even with the visceral type, early detection can prevent metastasis and potentially extend the cat's lifespan. Therefore, early detection and treatment are essential.

Since the cutaneous type is visible as dermatitis, consult a veterinarian immediately if you notice any skin abnormalities. The visceral type can only be detected through examinations like ultrasound. Therefore, in addition to skin symptoms, it is necessary to consult a veterinarian if symptoms such as vomiting are present.

Through early detection and treatment, let's ensure a better quality of life for your cat.