Plasmacytomas in Dogs

Generally, plasmacytomas are found on the legs or the trunk of the body. They can also be found in the mouth, feet or ears, although this is rare. Although not usually found in dogs, plasmacytomas most commonly occur in Cocker Spaniels and mixed breed dogs.

Plasmacytomas in dogs are skin tumors that develop rapidly. Plasma cell, a type of white blood cell, produces antibodies that aid in the identification and neutralization of foreign organisms in the body. Plasmacytoma is where the plasma cells malfunction and do not produce the antibodies that are necessary to destroy the foreign organisms or cancer cells.

Usually, plasmacytomas are solitary, solid nodules that are either raised or ulcerated. If you notice any lumps or nodules on your dog’s body or you notice any of these other symptoms, you should always have them examined by your veterinarian. 

• Visible appearance of nodules
• Lameness
• Pain
• Rectal bleeding
• Difficulty defecating
• Dark red or maroon stool

Types

There are two types of plasmacytomas: medullary and extramedullary. Plasmacytomas are classified according to whether the growth is in the bone marrow or not. Therefore, medullary plasmacytomas are found in the bone marrow. 

Extramedullary plasmacytomas are found in the soft tissue such as the mucous membranes or the skin. This includes tumors found within the gastrointestinal tract. These tumors are usually malignant and can recur locally or spread through the lymph nodes.

As with many cancers, the underlying cause of plasmacytomas has not yet been identified. It is known that the plasma cells in your dog’s body have a specialized function and work as a part of the immune system. Plasma cells form from B-type lymphocytes and they produce antibodies to fight off foreign organisms within the body. Plasmacytomas develop when the plasma cells begin to malfunction or they are unable to produce enough antibodies to fight off the foreign organisms.

Your veterinarian will request a thorough medical history on your dog and a description of the symptoms you have witnessed. They will ask you questions about diet, exercise and environmental factors. 

 full physical examination will be conducted. This will include palpating the chest and abdomen as well as feeling along the legs of your dog. A urinalysis, complete blood count and a biochemistry panel will be completed to rule out other possible causes. 

If nodules are present, your veterinarian will aspirate a nodule and take a biopsy to send to a veterinary pathologist for testing. Ultrasounds will also be used, looking for any abnormal growths within the trunk of the body, mainly focusing on the gastrointestinal tract.

Once your veterinarian has diagnosed plasmacytoma in your dog, they will discuss the treatment options with you. Generally, if the tumor or tumors have become invasive, your veterinarian will recommend surgery to remove the tumor and surrounding tissue. Radiation will be recommended following surgery to eradicate the cancerous cells that could not be removed with surgery. 

In some cases where plasmacytomas are located in the bone of the leg, removal of the leg may be necessary to eradicate the cancer. Skin tumors are usually the easiest to remove and many times do not require additional treatments.

Tumors within the body are much more difficult to remove and do have a higher rate of recurrence. They are removed surgically and radiation therapy is recommended. In some instances, chemotherapy is also recommended following surgery. 

During radiation therapy and chemotherapy your dog will need to have regular scans performed to monitor regular system functions such as kidney and liver. Regular scans will also be done to check for any additional tumors or suspicious masses.

When found early and treatments begun quickly, your dog’s prognosis is great. There are instances where your dog’s cancer has spread too quickly or it was not found early and the prognosis is poor. Speak with your veterinarian regarding your dog’s prognosis and expected recovery time. 

If your dog has nodules on their skin, keep them from licking or rubbing the nodules. Any ulcerated nodules should be kept clean and dry. If your dog has tumors in their mouth speak with your veterinarian about any special feeding instructions or types of food to avoid. 

Post-surgical care instructions will be given by your veterinarian. Be sure to follow their instructions completely. When you are administering medications follow all dosing instructions exactly unless otherwise directed by your veterinarian. If you have any questions regarding your dog’s care after surgery or their medications, you will need to ask your veterinarian.