A mast cell tumor (sometimes referred to as a mastocytoma) is a fairly common type of cancer in cats. These tumors can arise in the skin, in the spleen, or in the intestine. While some mast cell tumors are relatively benign, tending to be cured, others can be malignant and have a greater risk of spreading throughout the body.
Hearing the diagnosis of a mast cell tumor can be overwhelming. What caused this to happen? Where are we going from here? What though is a mast cell? This article will answer common questions about feline mast cell tumors, spotting signs, causes, treatment options, and more.
What are Mast Cells?
Mast cells play an important role in your cat’s health. They are a type of white blood cell that performs several important immune functions. If a cat is “attacked” by allergens, parasites, or even venom, mast cells are activated as one of the first responders in the immune system.
Mast cells release certain chemicals in an effort to restore the body to normal. One of these chemicals, which is quite well known, is histamine. Histamine is the chemical that triggers redness, swelling, and itching during an allergic reaction or hay fever episode.
What is a Mast Cell Tumor?
Mast cells, like many other cells in the body, can become cancerous. When this happens, the normal and controlled division of mast cells becomes de-railed, leading to the aggressive and uncontrolled proliferation of abnormal cells.
In cats, mast cell tumors can appear in three areas of the body:
- Skin (sometimes called a cutaneous mast cell tumor)
- Spleen (an organ that filters blood in the stomach)
- Intestines (intestines)
Signs of Mast Cell Tumors in Cats
The signs of mast cell tumors in cats are variable. These depend largely on which of the three areas above is affected, how aggressive the tumor is, and how far the cancer has progressed.
If the tumor is in the skin, you may notice a firm plaque (hard, flat area) or a lump under the skin; however, mast cell tumors can have many different appearances. Although it usually occurs around the head and neck, other areas of the skin can be affected. The lesion may itch as a result of the tumor releasing histamine.
If your cat has the splenic form of the disease, weight loss, vomiting and loss of appetite are common signs. These signs are vague or “non-specific”, and may be confused with other diseases.
If the tumor affects the intestines (intestines), gastrointestinal signs are more common. This includes vomiting and diarrhea. Fresh red blood may be seen in your cat’s stool, or the stool may have a dark/dried appearance (representing dissolved blood). Weight loss and loss of appetite are also possible. Unfortunately, feline mast cell tumors can spread to nearby organs and lymph nodes.
What Causes Mast Cell Tumors?
As with many cancers in pets and fellow humans, the exact cause of mast cell tumors remains unknown. The development of mast cell tumors is likely to be “multifactorial”, meaning that many factors contribute to tumor development. Some of these factors are environmental, and others are genetic or hereditary.
A small protein called KIT helps control or regulate mast cell division. It is believed that this KIT protein undergoes a mutation, which allows mast cell division to occur in an abnormal and aggressive manner.
Diagnosing a Mast Cell Tumor in Your Cat
Diagnosing a mast cell tumor can be very simple, or quite difficult. If the tumor is in the skin, your vet may take a fine needle aspirate and reach a fairly conclusive diagnosis. This involves using a small needle to “suck” some cells from the tumor, which are placed on a glass slide and examined under a microscope.
If mast cells and histamine granules are abundant, the tumor is likely a cutaneous mast cell tumor. Surgical biopsies may or may not be indicated.
However, it is not possible to perform a fine needle aspirate on splenic and intestinal mast cell tumors, because they are deeper, inside the stomach. These internal tumors are likely to be seen on an ultrasound or MRI scan of the abdomen. However, it is impossible to tell from imaging alone what type of tumor is present. Surgical (or endoscopic) biopsies are required to reach the diagnosis, with samples sent to an external laboratory for examination by a specialist pathologist.
Once the diagnosis of a mast cell tumor is made, staging can be performed. This includes performing blood tests, and imaging of the chest and abdomen, to see if the tumor has spread to other parts of the body. Enlarged lymph nodes should also be sampled.
How Do I Care for a Cat With a Mast Cell Tumor?
Caring for a cat with a mast cell tumor requires you to work closely with a trusted veterinarian. There are no home remedies for mast cell tumors, and it is not recommended to leave them untreated (unless your cat is in a palliative-care state). Surgical removal of tumors is the most common treatment.
It is important to note that the operation is always performed under general anesthesia in cats. For mast cell tumors of the skin, this may be the only treatment necessary to achieve a cure, although the risk of recurrence certainly exists. For splenic and intestinal mast cell tumors, a combination of surgery and chemotherapy may be necessary. Your vet will discuss this with you in more detail.
Antihistamines and antacid medications are often prescribed to help your cat feel better. After surgery, pain relief is required. Cats undergoing chemotherapy may also need antibiotics and anti-nausea medications. Treating aggressive mast cell tumors can be fairly involved, requiring frequent discussions with your veterinarian and several visits to the veterinary clinic for check-ups.
Frequently Asked Questions
Are There Any Natural Treatment Options for Mast Cell Tumors?
There are no natural remedies for mast cell tumors. Although the internet may be full of viable antihistamines, probiotics, and herbal formulas, there is no evidence to suggest that these will shrink or cure mast cell tumors. For cats undergoing appropriate surgical and chemotherapy treatments, natural remedies can be a useful adjunct, although they should always be discussed with your veterinarian.
What is the Prognosis for Cats with Mast Cell Tumors?
The prognosis for cats with a single or solitary mast cell skin tumor is good if surgery is performed. The risk of recurrence or spread to other organs is relatively low. Unfortunately, cats suffering from splenic or intestinal forms of mast cell tumors have a poorer prognosis. Some cats can live a long life after having their spleen removed. Intestinal mast cell tumors are worse, as they are common and rarely curable.
Which Races Are at Greater Risk of Mast Cell Tumors?
Siamese cats are believed to be more susceptible to mast cell tumors, although any cat can be affected.
Conclusion
Mast cell tumors are cancers that originate in one of the cells of the cat’s immune system. They can affect the skin, spleen, and intestines. The prognosis is variable, and appropriate veterinary treatment is recommended.
If you notice a lump on your cat’s skin, or if your cat is showing signs of being unwell, schedule a consultation with your veterinarian. Earlier detection of mast cell tumors often leads to better health outcomes for your cat.
Featured Image Credit: PRESSLAB, Shutterstock
