Mast Cell Tumors In Cats: Symptoms, Diagnosis & Treatment

What is a Mast cell?

A Mast cell is found in many tissues of the body and plays a vital role in people with allergies. When these allergy cells come into contact with allergens, they release histamine that causes symptoms such as itchiness or sneezing. However, when there is an overproduction (or mass degranulation) of mast cell compounds like histamine due to excessive amounts from allergen exposure, then full-body adverse effects may occur including dizziness or even death if left untreated.

What's a Mast Cell Tumor?

First, it's vital to understand precisely what a mast cell tumor is. Put simply, a mast cell tumor consists of mast cells.

Mast cells are white blood cells found in body tissues. Among other things, mast cells release a compound called histamine, which many people will recognize as the compound responsible for allergic reactions.

Mast cell tumors form masses or nodules in organs, although the most common location is the skin.

There are three types of tumors due to abnormal mast cells:

• Cutaneous
• Intestinal
• Visceral

Cutaneous: Skin

About 20% of these skin neoplasms are cutaneous, which means they are in the skin. These mast cells are common skin tumors and usually harmless, with about 90% diagnosed as benign.

As these forms of mast cells can be external, cat owners usually detect these early. They are also usually itchy and uncomfortable for your cat, so it's common for them to chew and itch the bumps formed by mast cells.

Visceral: Internal Organs

About half of these tumors from mast cells affect the spleen, meaning that they are visceral. It's also possible for the mast cells to affect the intestine, but the spleen is much more common.

Intestinal: Small Intestine

This form of mast cells is the most severe version of the tumor. When this is the case, the tumor has often spread to other organs and the lymph nodes, which results in fluid in the cat's abdomen.

What causes this cancer?

Why a particular cat may develop this, or any cancer is generally not straightforward. Very few cancers have a single known cause and most seem to be caused by an unknown mixture of environmental and genetic risks factors with some mutations in proteins being the key factor. The KIT protein mutation has been well-described in the development of MCTs (malignant cutaneous tumors) found on dogs which could also explain why 67% of cats afflicted by them would bear those same genes too.

What Are the Symptoms of Mast Cell Tumors in Cats?

The symptoms of a cats mast cell tumor depend on whether the feline has cell tumors that are visceral or cutaneous.

As mentioned above, a standard indicator of cutaneous mast cell tumors is hard, hairless bumps on the skin. Because tumors affect histamines, this formation can result in side effects common in allergies like itching.

If cats develop a visceral tumor, you won't see anything physically wrong with your cat. Instead, common symptoms include: 

• Loss of appetite
• Vomiting
• Weight loss

If your cat has the most severe form of feline mast cell tumor, which would be in the intestines, then the symptoms of mast cells will be more severe.

These could include:

• Diarrhea
• High blood pressure
• Stool with fresh blood
• Vomiting
• Black stool

How Are Mast Cell Tumors Diagnosed?

While learning about the symptoms might be scary, formally diagnosing this type of cancer of mast cell tumors is easy to accomplish. A needle inserted in the mass suctions out some cells in a procedure called a fine-needle aspiration (FNA).

Once the vet has done this, they use a procedure called cytology. This process refers to examining the cells with a microscope.

Blood work is also a standard step that a veterinarian will take in diagnosis, but examining the cells under a microscope is the most accurate method.

A diagnosis can often result from this process, but sometimes the results aren't conclusive. There will need to be a biopsy of the tumor to examine mast cells for surgical removal in those cases.

While this process is much more invasive, it provides a lot of valuable information. A pathologist can determine the type of tumor, the margins between cancerous and healthy mast cells, the tumor diameter, and how aggressive it is through a biopsy.

How To Treat Mast Cell Tumors in Cats

Mast cells in a tumor are sensitive to physical manipulation and when this occurs, histamines can be released into the bloodstream. Treatment with antihistamine medication will help relieve symptoms of allergies due to an increase in histamines. Surgical intervention may also result in such release as mast cell activity is disrupted by cuts or other types of trauma during surgery on organs; thus antihistamine medications would need use under these circumstances too.

Treatment of choice for mast cell tumors has always been surgery, but there may be some new and alternative treatments on the horizon. One proposed treatment is surgical removal of the spleen as well as chemotherapy to inhibit further growth in those cases where blood cells travel together with cancerous ones; however, this method still needs more research before it becomes a viable option.

Small, incisional biopsy is sufficient for very small tumors. For large mast cell tumors that cannot be surgically removed with the aid of anti-histamine therapy because they are too big or because it would take to long and cause pain to a pet owner's beloved animal, an internal excisional biopsy may provide enough information on size grading as well as prognosis analysis by providing tissue samples from different layers in order to identify cancer cells more efficiently. Biopsying suspicious lymph nodes can also help veterinarians make better decisions about treatment options before considering surgery first which will probably include cutting margins wider than normal so there is no chance of leaving any trace behind during surgical procedures due to both their effectiveness against recurrence and prevention of metastasis.

Grading System and Prognosis

Along with the different types of tumors, there are also grades assigned to each case of mast cell tumors. These are more in-depth diagnoses and can help determine what kind of treatment is best for the cat involved.

There are two primary grading schemes used to determine these:

• The Patnik System 
• The Kipuel System

In terms of a diagnosis, the pathologist will often use both systems to get the most accurate result. The Patnik system grades these tumors as either a grade I, grade II, or Grade III.

The Kipuel system serves to clear up some of the ambiguity of the grade II explanation and instead assigns the tumor to one of two categories: low grade or high grade. 

The Patnaik System

Grade I

In terms of tumors, many practitioners consider grade I to have the best prognosis. Tumors of this grade tend to be on the skin and can be quite large, which may lead to panic. In actuality, these don't tend to spread beyond that first area.

These tumors are octopus-shaped, which means that it may look like one large bump on the surface but instead has "tentacles" that extend away from the growth of the visible mast cells.

Thus, even though these tumors can be easy to remove surgically with no need for chemotherapy or other treatments, it is critical to conduct a biopsy. A full report will ensure the removal of the tumor. If not, it has the potential to regrow. 

Grade II

A grade II tumor from mast cells is often "unpredictable," which makes prognosis difficult. When this is the case, a method called Agnor staining is often necessary.

With this procedure, the practitioner stains the tumor with silver particles, and a pathologist analyzes this to determine malignant behavior indicators. The uncertainty of this method first prompted the use of the Kiupel system. This system involved determining the mitotic index of the tumor. However, it can also be subjective.

Grade III

Grade III tumors make up an estimated 25% of these mast cell tumors; they are the worst out of the diagnosis. At this stage, the tumor is aggressive and spreads to areas like the bone marrow, liver, and spleen. These organs are hard to treat due to the tumor's location.

Surgery for grade III on its own isn't usually effective, so treatments such as radiation therapy and chemotherapy are often the only course of action.

Conclusion

If you find yourself in a situation where you think your cat has mast cell cancer, it's crucial to educate yourself about mast cells and seek advice from a veterinary professional. There are several types of cats mast cell tumors and different methods of treatment. A doctor can help you diagnose your cat with the right help it needs.

There are also products you can purchase to alleviate symptoms, like CBD catnip. With the help of a professional, you can choose which products are right for your pet.

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