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What are Plasmacytomas?

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.


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Symptoms of Plasmacytomas in Dogs

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


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.

Causes of Plasmacytomas in Dogs

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.

Diagnosis of Plasmacytomas in Dogs

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.

Treatment of Plasmacytomas in Dogs

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.

Recovery of Plasmacytomas in Dogs

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.

Plasmacytomas Questions and Advice from Veterinary Professionals

Staffordshire Bull Terrier
12 Years
Mild condition
0 found helpful
Mild condition

Has Symptoms

Blood In Stool

I was wondering if someone could give me some advice. My dog has just been diagnosed with a rectal plasmacytoma. The specialist isn't in until Wednesday and so far all I've been told is surgery is the only option. After reading about the pull through surgery suggested the risks are ridiculously high without adding on the fact she's almost 13 which I'm sure would increase the risks more. Is there any other option other than surgery? I simply can't put her through all that and risk losing her under the knife too, this is hard enough as it is. I'd really appreciate any advice as this is driving me mad waiting for the specialist to call! Thanks.

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10 Years
Mild condition
0 found helpful
Mild condition

Has Symptoms


I have a 10 year old labradoodle diagnosed with a rectal plasmacytoma that has metastisized to her lymph nodes in her abdomen, but no where else (that they can see). Most of what I've read suggests these tumors don't tend to metasticize. Even then they don't, median survival time is 15 months with treatment (according to study of 9 dogs). Clinic wants to do surgery to remove the lymph nodes and the remainder of primary tumor (most was removed by vet). Wondering if anyone else has had this scenario. Is it worth it to remove lymph nodes and do chemo if median survival is 15 months, and it is slow growing? Seems like outcomes are roughly the same with or without treatment.

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Australian Shepherd
3 Years
Fair condition
1 found helpful
Fair condition

Has Symptoms

Plasmacytoma on leg

I found a lump on my 3 year old female Australian Shepherd back leg. Long story short I asked vet to test it. It came back as a benign plasmacytoma. I was originally putting neosporin on it but switched to hydrocortisone cream, per vet request. They initially thought it was a histiocytoma. As pathology came back as the plasmacytoma, vet said to continue to keep clean and not allow her to play with it. They said that it needed to be removed. It may get bigger and cause problems. Also that the hydrocortisone cream would probably not do anything. Well since I found it, she found it and was obsessively trying to lick. At first I tried a cone and my little contortionist could get her leg in it. I tried different sizes too. So well she licked a wound on it or maybe from playing. So I started to just alternate between neosporin and hydrocortisone cream, use nonstick gauze and wrap her leg with the self ahesive wrap. I told her no, she licks around it but can’t get at it. Well I swear this thing has never looked better. It is also smaller, I have been doing this for over a week. Not sure about around but definitely flatter. She goes to vet today for normal physical. I am sure they will check. Her surgery is scheduled for Aug 6. I am wondering if I can get some advice? I am not sure if I should push surgery off or not taking any chance? Reading some of the stories I am worried about it going in her bone. Just not sure if anyone has heard this? My vet seemed to think nothing but surgery could treat it?

Dr. Michele King, DVM
Dr. Michele King, DVM
1611 Recommendations
If the lump was histologically identified as a plasmacytoma, it would be best to have it surgically removed. Your veterinarian will be able to advise you further, but with that diagnosis, it would be best not to take chances.

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English Bulldog
10 Years
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

Excessive Sleeping
Swollen nipple
Lethargy, rapid breathing at times
Worsening snoring

Medication Used

Melphalan 2mg QOD

My 10yo English Bulldog had a plasma cell tumor removed from the bottom of his foot almost 2 years ago. Last fall his toe started swelling and our vet did a X-ray that showed most of the bone in that toe was mostly gone and had basically “eaten away by something “. So we amputated the toe and it came back malignant. Vet called an oncologist to discuss it and they said the plasma cell tumor had came back into the toe and they diagnosed him with plasma cell cancer. They said it was very rare and offered radiation and chemo. Also offered to do further testing to see if it had spread. At his age I didn’t want to put him through all of that, but we decided to try the chemo. They prescribed Melphalan 2mg every other day. He does well on it, but I have noticed he sleeps more now and seems to have trouble breathing at night when he sleeps. He has actually gained weight and still has a great appetite. All of his blood work always comes back great, they also did a chest X-ray about a month ago. I’m just terrified that maybe the chemo isn’t enough or maybe it’s harming him and I don’t know. You all seem very knowledgeable about this disease so I thought I would get your opinion. Thanks for your time!!

Dr. Michele King, DVM
Dr. Michele King, DVM
1611 Recommendations
Side effects of that drug tend to be more Gi in nature, with nausea, vomiting, and diarrhea sometimes resulting from administration. If he is having problems breathing at night, that may be more related to him being a bulldog than the drugs, and a clear chest x-ray is positive. Frequent rechecks with your veterinarian would be a good idea to make sure that his breathing problems aren't something that needs to be treated. I hope that Bogger does well with his chemotherapy.

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