Plasmacytoma In Dogs

Plasmacytoma is an uncommon tumor of dogs. There are two forms, medullary and extramedullary according to whether the growth is in the bone marrow or not, respectively. Today we will be discussing extramedullary plasmacytoma. This is a continuation of our series on round cell tumors which began with canine histiocytoma, followed by canine transmissible venereal tumor.

Canine extramedullary plasmacytomas are most likely to occur on mucus membranes and/or skin. The head is a common location for them, with the areas of the face, ears and lips frequently affected. However, lesions also commonly occur on the trunk as well as the feet and toes.

Typically canine extramedullary plasmacytoma is a tumor of older dogs. They arise with the appearance of raised, red nodules. Rarely is the general health of the patient affected unless the mass is in the mouth or rectum, in which case obstruction may occur.

Differential diagnosis must include multiple myeloma, especially if systemic disability is observed.

Treatment is primarily focused on surgical excision. However, given the typical locations in which they occur, surgical excision may, by necessity, be incomplete. For example, rectal and oral lesions may not allow removal of all of a tumor mass if large quantities of tissue must be excised. Sufficient skin to close a surgical site may exist for a small foot lesion, but this is a part of the body which has little skin to spare. Large lesions may require amputation.

On the other hand, growths on the trunk usually allow for wide surgical margins, removing all of the cancerous cells. In these cases prognosis is favorable.

For plasmacytomas which cannot be completely removed surgically, chemotherapy and radiation are good treatment options for many patients.

See you tomorrow, Dr. Randolph.


  1. Hi Dr. Randolph, My approximately 14 year old (we think that’s her age, she is a rescue) border collie, Emma, has been bleeding on and off from her rectum for about a year. Sometimes it might be just a drop or two on the stool, other times it has been more globular and “muscousy”. Or sometimes, there is no trace of blood at all. It has never been a bright red, more of a dark maroon color. Our vet has X-rayed, probed, examined and has not been able to find the cause. A few days ago, she began bleeding bright red blood profusely from her rectum. While looking at her closely, my husband saw a protruding “mass” in her rectum. He was able to gently remove it and we rushed Emma and the “mass” to our vet. He referred us to another local vet who specializes in internal medicine. The internist’s lab analysis shows it to be a plasmacytoma. I have spoken with the internist about our options and he has recommended chemotherapy OR a round of tests to determine the extent of the cancer. He told me that most dogs can tolerate chemo pretty well and that after one injection it would be given as an oral dose at home. Given her age, I would think chemo would be a better option. But, I am concerned that it might be hard on her and I don’t want to negatively affect her quality of life. Can you weigh in with your opinion on chemo? I want to do whatever I can for Emma to keep her able to have a good life and keep chasing balls. Thank you so much for your help. Margaret Jones

    • I can do better than weigh in. I can have my favorite board-certified oncologist weigh in. Click here to read her opinion. I am so sorry that you are having to face this. You will thank yourselves for doing what you can. Just plan ahead to know when to say no; there will come a time when you have to let go. I had a patient with a rectal mass we had to let go of just this past Saturday. It was hard, but when her bleeding got to a point that it was uncontrollable, it was time. Neither we nor the pet’s owners wanted to see her have a massive bleeding episode at home. Our best wishes to you, and please stay in touch so we can know about Emma’s progression, Dr. Randolph.

      • Hi Dr. Randolph, I am sorry that I haven’t gotten back to you to say thank you for the information and the kind advice. We decided not to go with chemo and went with a program of immune boosting supplements and vitamins. And it seemed to really help. There were some additional bleeding episodes, but very, very slight and far in between. Unfortunately, Emma developed what we think was degenerative myelopathy as her hips just began to get weaker and weaker. We eliminated everything else until that was left. She wasn’t in pain, so we got used to lifting her and putting throw rugs literally all over our house to give her traction. She was still a happy dog and still wanted to catch a ball..from a sitting position. But, on January 28, 2015, we let her go. She lost control of her bowels, and that upset her too much. The hardest thing I have ever had to do. I miss her every day. She was my “once in a lifetime dog”.
        We have since rescued two more dogs, a 15 month Border Collie/Malamute mix and a 7 year old former working Border Collie. Both are females and have issues…and we are working on that. They are loving, sweet dogs and they are keeping me busy. Thank you again for your caring about Emma. Your advice was really helpful and comforting to me.

        • We are so sorry for your loss, so happy that we could be a bit of help, and find it encouraging that you have consoled yourselves by jumping back in with a couple of new dogs. I can’t say that I’ve ever had a “once in a lifetime dog,” but my Brenda has. For her, it was our Peyton. Click here to read Peyton’s story. So, even if by proxy, I know what that’s like. It has been theorized that I have a favorite, though. Click here to read how that theory came to light. May both of your new dogs have long, happy lives. Thank you for your readership, Dr. Randolph.

  2. Dear Dr. Randolph, Firstly, thank you for this informative site and for the effort that you put in to replying to people here; I think it’s wonderful. Secondly, I would be most grateful if you could answer a question for me; perhaps not so well-informed as yet on this subject, sorry for that. My adorable and fabulous Welsh collie has managed to reach approx. 20 years old (approx. because he was a rescue dog and thought to be around 4 when I got him). I have noticed in the last few days he has 2 small ‘nodes:’ 1 on his head and 1 on his ear. The one on his ear was red a couple of days ago, now normal flesh colour. The one on his head is now red. They are small, not entirely round, a bit like a tick in the early stages (slightly elongated) but definitely not ticks. I think he had one once on his ankle that was examined and thought to be probably a wart, but the hind leg was recently examined by another veterinarian who said she thought there was a lump in the upper right hind leg – possibly another fatty lump as he has a couple of those. I am wondering if the “nodes” are warts or cancers, if they can signify any other cancer, eg. in his leg, if there is a pattern. To provide some background, he started to go blind a few years ago following a bout of vestibular syndrome, is on vivitonin. He also has arthritis, beginning in his legs and later in his spine (his lower back now curves a bit) and has persistent weakness in his right hind leg, the focus of my question, along with the nodes. He had a myriad of treatments, including X-rays and swimming, but the weakness in the leg has persisted. He has not been checked for cancer specifically, but has has other large fatty lumps aspirated (to show fat). He has recently been fighting a long battle with repeated bladder infections and is just about to finish another course of antibiotics; still on special food. He seems to be getting weaker. I don’t want to subject him to too much unpleasantness, but am wondering if I should have him checked specifically for cancer, if it would be too much, or too late, or totally unnecessary. Based on the scant info I have provided, can you offer any suggestion or advice ?

    • 1. Janet, you are most welcome.
      2. To read more about vestibular syndrome click here.
      3. While your description of the lumps on your collie are excellent, there is no way I can diagnose them by the description alone. Click here to read a post that explains why. Your local veterinarian can examine the lumps and determine whether additional steps are warranted. Fine Needle Aspiration is a relatively painless and minimally-invasive way to look inside the lumps without surgery. Click here to read about FNA. That the lumps have redness that comes and goes is a bit of concern.
      I hope this has helped you. Please write back and let us know what your veterinarian finds out. You are most fortunate to have had your dog live to 20 years. Click here to read more about dog and cat aging. It took a lot of TLC for him to live so long.
      Best wishes, Dr. Randolph.

  3. Hello Dr. Randolph,
    My 10 1/2 year old miniature dachshund has a small pinkish bump on his trunk. Here are the exact words from the report his veterinarian gave to me.
    “Source: Small round superficial lesion, firm, ventral truncal region according to the history and diagram.
    Description/Microscopic Findings/Comments:
    The smear is highly cellular showing a population of neoplastic round cells possessing round to ovate eccentrically located nuclei, an occasional small pale nucleolus and generally small to moderate amounts of basophilic cytoplasm. Occasional perinuclear clearing is evident imparting a plasmacytoid appearance. Some possess several small clear vacuoles. A few bi- and multinucleate cells are observed. There is an abundant pink amorphous background. Blood elements and dermal debris makes up the remainder of this specimen.
    Conclusion: Plasmacytoma
    Comment: Findings are compatible with a round cell tumor. Plasmacytoma as well as other round cell neoplasia would have to be considered. Excisional biopsy would be indicated for definitive diagnosis. A favorable prognosis would be expected based on cytologic features.”
    Our vet is at Banfield, and she says this is her “first plasmacytoma.” She wants to remove it and do a dental at the same time. I am concerned about long term anesthesia. Should I have it removed? Should I look for someone with more experience?
    This little guy is my love, and I want to make sure I am doing the right thing.
    Thanks so much for your help.

    • Thank you for a very complete history. Here is how I would handle this if I were a layman faced with your situation. Have a sit-down with the Banfield doctor and say something to the effect of, “I want to ensure that I have the best possible outcome in this situation. Are you confident that you can provide ‘clean margins’ (click here to read about the concept of clean margins) laterally and deep to the tumor, along with safety in anesthesia? I am both willing and financially able to take him to a board-certified surgeon and/or oncologist, if you think a specialist(s) could add safety and improve his outlook for a full lifespan.”
      Keep in mind that even though this is her first plasmacytoma, if she has a valid license, she has had surgical training in elliptical excision (click here to read about elliptical excision) and clean margins, and those foundational principles apply to every tumor removal we do.
      You might also ask her how confident she is that he will not experience infection at the surgery site from bacteria released into the bloodstream during dental prophylaxis. Some practitioners do such procedures together all the time. Others prefer to have them be separate procedures. While it is the surgeon’s choice, it is ultimately your decision. If you prefer, you could have them scheduled separately, a month or two apart.

      • Thank you so much Dr. Randolph for your reply. I will meet with the Banfield veterinarian and make a decision. We may ask for a referral to the Veterinarian Specialty Hospital of the Carolinas. They have a location just a few miles from my home.
        Wishing you the best 2014 has to offer.

  4. I was just told that my dog has a plasmacytoma tumor in his ear, but my veterinarian said that it is not cancer and he can remove it. I read here that if it is not all removed that chemotherapy and radiation should be used. My veterinarian said that if he can not get it all out it is not life threatening. Is this correct? Am sort of confused. I have a 9 year old cocker spaniel and his name is Toby. He had a tumor removed from his elbow about 3 years ago but it was not this type and he has been doing great and there are no other signs of a tumor any other place on him but in his left ear canal.

    • To quote from the movie, Cool Hand Luke, “What we have here is a failure to communicate.” I suspect that your veterinarian has information from a Fine Needle Aspirate having been read by a pathologist. Did the FNA say that Toby’s plasmacytoma was particularly not aggressive? Typically, plasmacytomas are notorious for local recurrence if the entire mass is not excised. I have removed entire pinnas from dogs because of these. The ear canal, especially the vertical ear canal, is another matter. Surgery there is very tricky. Parts of the horizontal ear canal are easier to work in and may more readily allow complete excision. Have another sit-down talk with your pet’s doctor and be sure you are both on the same page for your expectations. Some information may have slipped through the cracks in the translation. And, please keep us posted on Toby’s condition.

  5. My 7 year old Carolina Dog mix has been diagnosed with a plasmacytoma that is on the side of the large pad on his right back foot. Surgery has been recommended by my veterinarian. Since this in on the foot and they are going to have to remove part of the pad, should I have my general practitioner remove this tumor? Also, is this a cancerous tumor?

    • Cindy, we’re sorry to hear that your dog has been affected by plasmacytoma. The behavior of the tumor is well-covered in this post. As to who should perform the surgery it is a decision you and your GP should discuss together. If he feels he is qualified to perform the procedure AND you have confidence in him to do so, by all means, proceed. If, however, you have doubts, feel free to ask for a referral to a board-certified surgeon and/or oncologist. Many specialty practices house both specialties under one roof. Please keep us posted on your dog’s progress and outcome.

  6. Hi Again, Dr. Randolph. Maggie Mae, my elderly Great Dane, has no longer been on aspirin and seems to have made as complete a recovery as an almost 13 year old can make. This past week while going through some old scrapbooks I found a picture of her taken the day I got her at 4 1/2 months – on December 18th, 1999. I’ve been off a year on her age! Just thought it might be of interest to you that she’s a bit more remarkable than I’d thought! Best wishes – Joan

  7. Thank you for getting back to me so promptly, Dr. Randolph. For the past 3 days there has been no more sign of blood; Maggie has eaten as usual; however she appears to be very tired and is sleeping more.
    As to the aspirin – my doctor said I should take a baby aspirin a day. I thought with Maggie so elderly it might benefit her as well. Today I bought Senior dog food – smaller kibbles and I am adding a bit of rye bread pieces to the cat snack already in her meals. She likes this and as I said, is eatting and able to go outside as usual. Barry and I will hold on to our dear friend as long as she allows. Thank you again. Joan

    • Joan, I’m glad Maggie’s stool is blood-free, yet I’m concerned that she continues to be lethargic. If you can’t get her to see a veterinarian perhaps the house-call approach will work for you. Some laboratory tests might point a doctor in the direction he should go. Your thinking was on the right track with the aspirin, but it’s not applicable to most dogs. As dogs are primarily carnivores, their risk of atherosclerosis and thrombocytic clots is quite low, whereas people’s platelets (which come from thrombocytes) can be high, thus the aspirin is useful as a preventive measure in people. I doubt that your local veterinarian would approve of its use in Maggie’s case. It is my fervent prayer that you will have Maggie for a long, long time yet. Thanks for the good news, Dr. Randolph.

  8. My Harlequin Dane Maggie is now almost 12. Yesterday I noticed a few drops of blood from her rectum as I was putting her out in the a.m. She ate as usual, and again later in the day. The blood is not steady. I have stopped her daily baby aspirin and now will watch to see if the drops return. Should I be taking a more active step to find out what is wrong? My problem is she will no longer get in my car, so transporting her is another issue. Plus she would be so afraid at the vet. At almost 12, I do not expect a miracle. I and my cat, Maggie’s dear friend Barry, have already begun our grieving. Thank you for your past responses to my inquiries. I wrote you last May 25, 2011.

    • Dear Ms. Best, It is good to hear from you again. I’m sorry it’s with bad news about Maggie. Of course, the best route is to have a doctor examine her and try to find the source of the blood. House-call and mobile practices abound these days, so there may be a veterinarian in your area who could see Maggie right there in your own home. Alternatively, knowing that the prognosis is not particularly good for a Great Dane in her age group, you could let Nature take her course. But, what if this isn’t something fatal, but something that could be fixed. You and Barry might end up having Maggie a lot longer. We just don’t know without that examination. You are smart to discontinue aspirin therapy, as it certainly can contribute to bleeding. I’m also curious about why she’s on an aspirin regimen. Please post another comment on this page and write back when you can. Best wishes, Dr. Randolph.

  9. This article is very informative and easily understood. I had hoped to determine whether or not there is medication which could be bought to assist a dog that has had plasmacytoma removed from the mouth.

    • Elaine, you can be referred to a board-certified veterinary oncologist by your general practitioner for recommendations for followup chemotherapy, radiation, etc. Alternatively, if your pet’s doctor has time he might be able to talk to an oncologist he has a relationship with, or the veterinary college he graduated from. Best wishes on his full recovery, Dr. Randolph.

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