The Furry Critter Network

Plasmacytoma - Issue Description

Back to Canine Health Issues Menu


Issue Name


Other Names

Issue Description

Extramedullary plasmacytomas are tumors of plasma cells that occur outside the bone marrow cavity. The most common location of these neoplasms is the skin or mucous membranes, especially the lip, digits, trunk, ears, and face. Plasmacytomas are not very common tumors in dogs, but it is thought that they may be underrepresented due to misclassification as different tumor types.


Plasmacytomas are usually solitary raised nodules that appear red and sometimes ulcerated, especially neoplasms on the digits. Cutaneous and mucocutaneous plasmacytomas usually lack clinical signs of disease; however, oral and rectal plasmacytomas have been associated with gagging or rectal prolapse, respectively. If signs of generalized illness are present concurrently, the possibility of multiple myeloma should be excluded.


It is diagnosed by immunoglobulin electrophoresis (or Serum protein electrophoresis) and bone marrow biopsy. Immunoglobulin electrophoresis will show a monoclonal M spike, but bone marrow biopsy will fail to find the classical signs of multiple myeloma. After those two determinations are made, search for the primary site in the soft tissue begins.


They usually occur on older dogs, with a mean age between 9 and 10 years. There appears to be no sex predilection although some studies found that more males than females were affected. While many breeds were represented in these reports, one study found that Cocker Spaniels were more commonly affected.

There can be some ambiguity when using the word:

  • Plasmacytoma" is sometimes equated with "plasma cell dyscrasia" or "solitary myeloma".
  • It is often used as part of the phrase "solitary plasmacytoma".
  • It is also used as part of the phrase "extramedullary plasmacytoma ". In this context, "extramedullary" means outside of the bone marrow.
  • Treatment

    Surgical excision is the treatment of choice for plasmacytomas and generally results in a favorable prognosis.


    Canine (muco)cutaneous plasmacytomas are mostly benign and thus differ from both multiple myelomas and extramedullary plasmacytomas of internal organs, which often metastasise. After surgical excision of (muco)cutaneous plasmacytomas, dogs have remained tumour-free for long periods, although metastasis to lymph nodes has been reported. Whether these metastases originated from primary (muco)cutaneous plasmacytomas or from multiple myeloma remains unclear, because tests were not carried out to exclude the possibility of primary multiple myeloma.

    The relationship between the localisation or cell type of the (muco)cutaneous plasmacytomas and their biological behavior have been investigated to determine the prognosis of these tumours. The clinical outcome of cutaneous plasmacytomas is not influenced by either anatomical site or histological appearance. However, well-differentiated tumours are most often found in the skin of the lip and the ear, whereas the poorly differentiated tumours preferentially affect the skin of the digits. Results from one study suggested less benign behavior for plasmacytomas with the polymorphous-blastic cell type, whereas in another study it was concluded that almost all cases had a good prognosis.

    Back to Canine Health Issues Menu

    Featured Rescues

    "Don't Shop ... Please Adopt"

    laptop pro


    The American Society for the Prevention of Cruelty to Animals® (ASPCA®) was the first humane society to be established in North America and is, today, one of the largest in the world.

    Our organization was founded on the belief that animals are entitled to kind and respectful treatment at the hands of humans and must be protected under the law. Headquartered in New York City, the ASPCA maintains a strong local presence, and with programs that extend our anti-cruelty mission across the country, we are recognized as a national animal welfare organization. We are a privately funded 501(c)(3) not-for-profit corporation, and are proud to boast more than 2 million supporters across the country.

    The ASPCA’s mission, as stated by founder Henry Bergh in 1866, is “to provide effective means for the prevention of cruelty to animals throughout the United States.”

    laptop pro


    If you can’t find the pet you’re looking for on Petfinder, don’t give up. Some shelters maintain waiting lists for specific breeds, so don’t be afraid to ask! There are also breed-specific rescues for just about every breed, and most of them post their pets on Petfinder. (Petfinder can even e-mail you when a pet that fits your criteria is posted — just click “Save this Search” at the top of your search results page.)

    laptop pro

    Rescue Me

    Jeff Gold, Founder, Rescue Me! Animal Rescue Network

    Jeff Gold lives in Watkinsville, Georgia on the same property as Rescue Me's Animal Rehabilitation Center, with 18 rescue animals. Shown with him in the photo to the left are Maggie, Izzie and Cortez. In 2003, after learning there was nobody doing boxer rescue work in Georgia, Gold founded Boxertown, an organization which helped find homes for over 500 boxers during its first two years. Based upon this success, Gold came up with the vision for Rescue Me! ― a network which helps all breeds of dogs, cats and other animals find good homes, anywhere in the world. is also a free service of Rescue Me! and provides the world's largest and most up-to-date directory of animal rescue organizations for all breeds of dogs, cats and other animals, including a comprehensive directory of wildlife rehabilitators in over 150 countries.