Skin Cancer (Mucocutaneous Plasmacytoma) in Dogs

Mucocutaneous plasmacytoma is a cancerous condition that occurs on the skin and other cutaneous surfaces. The tumors are generally fairly small and found on the face, legs, feet and ears most commonly, although they can also develop in the mouth, or on internal surfaces such as the intestinal tract. It is actually a cancer that affects the plasma cells in the blood, which causes the plasma cells to grow out of control. Although it is a generally fairly benign condition, mucocutaneous plasmacytoma is closely related to more serious disorders such multiple myeloma.

Mucocutaneous Plasmacytoma is a blood plasma cancer that causes tumors on the skin and other cutaneous surfaces. Although generally benign, it is related to more serious blood cell cancers and should be checked by a veterinarian.

These skin tumors usually only get to 1-2 cm in diameter with the occasional outlier and may bleed. Although single tumors are more common, multiple tumors can also grow, most often in the oral cavity. You may also see symptoms related to placement, such as breathing problems from growths in the airway or nosebleeds from growths in the nostrils. It is also possible for the plasmacytoma to grow internally, and when it does it can interfere with the functionality of the organ it is growing on. 

Types

Although the symptoms manifest on the skin, the disorder itself starts in the blood. Other cancers that involve an overgrowth of plasma include:

Multiple myeloma

• This is the most aggressive of the plasma cell cancers, and usually affects mainly the bones rather than the skin
• It causes weakening of the bone structure and suppresses the formation of bone marrow
• With chemotherapy, some canine’s lives are extended by a few years

Solitary osseous plasmacytoma

• This is a rare condition which also affects the bones rather than cutaneous surfaces
• The principal worry with these tumors is that they often turn into multiple myeloma
• They are aggressively treated using physical surgery, radiotherapy, and chemotherapy

The symptoms that manifest on the skin are actually symptoms of a plasma cell cancer. When the plasma cells start to multiply out of control these cutaneous tumors will eventually form. The causes of any cancer can be ambiguous but there are some things that can trigger the formation of mucocutaneous plasmacytoma.

• Advancing age
• Exposure to chemicals
• Genetic predisposition (Airedales, Boxers, Cocker Spaniels, Golden Retrievers, Scottish Terriers, Standard Poodles, West Highland White Terriers, Yorkshire Terriers)
• Hormones
• Infections
• Radiation

Your veterinarian is likely to start with a physical examination of the masses or lesions and will also want to get a sample of the tissue so that it can be examined more closely. A complete blood count, biochemistry profile, and urinalysis are also likely to be done at this time as well, with special attention being paid to the proteins present in the blood. Depending on size and placement of the tumor, the veterinarian will generally take their sample using either a needle aspiration, punch biopsy or full excision technique. The sample will then be examined under a microscope, which will reveal the presence of the plasma cell cancer. Testing of the lymph nodes may occur to ensure that the plasma cell cancer has not spread and if the tumor was excised in order to biopsy it, the edges will be checked at this point to ensure they got the entire tumor. In many circumstances, a bone marrow biopsy may also be recommended. This test would be run in order to verify that the more serious plasma cell cancers of solitary osseous plasmacytoma or multiple myelomas are not developing concurrently in the bone.

Treating these tumors is quite often as simple as removing them, once the diagnosis is determined. With many mucocutaneous plasmacytomas, especially those on the body itself rather than in the mouth or intestinal tract, excision and subsequent examination of the tumor is enough to prevent any recurrences. In the event that a tumor forms again the excision will be repeated, but then followed by radiation and chemotherapy treatment as well. 

Our furry companions actually tolerate chemotherapy better than most humans and only around 5% require hospitalization from the treatment itself. There is less reported hair loss than in the human animal, but some breeds (English Sheepdog, Lhasa Apso, Maltese, Schnauzer, Shih Tzu, and Poodle) are more prone to hair loss.

Tumors formed in the intestinal tract or other soft tissues can be somewhat more aggressive and spread throughout the body and because of this the more aggressive radiation and chemotherapy is often recommended to prevent further tumors of the skin and bone from developing. There are additional circumstances which could make surgery a less viable option, such as placement of the tumor or the presence of multiple tumors, and chemotherapy or radiation therapy would be indicated for these situations as well.

After any excision, it is important to keep the surgical site clean and free from debris. You will need to keep your pet from interfering with the site, and examine it for swelling, bleeding or pus, and to ensure that the stitches are intact. Specialized feeding and care instructions may be given in the case of tumors that were removed from the mouth or any part of the digestive tract. Complications from chemotherapy can arise, so your veterinarian will probably want to do regular checks on your dog’s liver and kidney enzyme levels. Pets are often sent home the same day after chemotherapy, and although most of the drug is metabolized within just a few hours, some remnants of it can remain in the blood for a few days. It is important to use gloves when dealing with bodily fluids, and maintain good hand washing hygiene. Children, pregnant and nursing women and immunocompromised adults should avoid contact with the bodily fluids during that time.