Plasma Cell Cancer in Dogs

Cancer in dogs can affect various organs and cells. Plasma cell cancer occurs when the white blood cells multiply uncontrollably and become malignant. Plasma cells belong to the immune system and are responsible for the formation of antibodies which help the organism fight diseases. When plasma cells multiply beyond control, they can cause several types of cancer in dogs.

Plasma Cell Cancer in Dogs

Plasma cells have an active role in defending the body against diseases. They are part of the immune system and are usually located in lymphatic tissue and mucosal surfaces. In some cases they harm the body by multiplying uncontrollably. When they become malignant, plasma cells become round and larger than their normal size. They replicate at a higher rate and produce more immunoglobulin.

Malignant plasma cells can result in different types of cancer: extramedullary plasmacytoma, solitary osseous plasmacytoma and multiple myeloma.

Extramedullary Plasmacytoma

Extramedullary plasmacytoma is common in dogs. The tumors form from soft tissue, located on the surface of the skin (more than 75% of cases), the oral cavity (around 20% of cases) and in rare cases it can affect internal organs, genitals or eyes (around 5% of cases).

Extramedullary plasmacytoma is not an aggressive disease and it is usually curable by surgical excision; however, if it spreads to other locations, surgery is not possible. It usually affects older animals.

When located in the oral cavity and skin, extramedullary plasmacytoma has the appearance of a tumor: red and sometimes ulcerated.

If extramedullary plasmacytoma affects internal organs, specific signs might manifest.

Solitary Osseous Plasmacytoma

Solitary osseous plasmacytoma forms in the bone tissue. The tumors are usually formed on the vertebral body, the ribs and the zygomatic arch in the skull. In very rare cases they can be located on long bones.  

Depending on the location, the tumor causes bone pain, pathologic fractures, lameness or neurologic problems.

Solitary osseous plasmacytoma only occurs rarely in dogs.  It usually turns into multiple myeloma. Treatment involves surgery, radiotherapy and chemotherapy, but the prognosis is worse than in case on extramedullary plasmacytoma.

Multiple Myeloma

Multiple myeloma is more aggressive than other plasma cell cancer forms. It usually develops from solitary osseous plasmacytoma and affects older dogs.

Myeloma affects mainly the bones. It causes bone diseases, pathological fractures, diffuse osteoporosis and suppresses the bone marrow. Myeloma also increases the calcium levels in the blood and thickens it. These changes which occur in the blood can trigger heart conditions.

Dogs suffering from myeloma can also manifest bleeding diathesis, the predisposition to hemorrhages caused by the blood’s inability to coagulate normally.  

Myeloma can also affect renal functions and even penetrate kidney tissue.  

Surgery is not an option, so chemotherapy is typically the chosen course of treatment. The treatment does not destroy all malignant cells, but delays the progression of the disease. Secondary conditions have to be treated as well. They can also be managed through decreasing the primary tumor.

In the best case scenario, dogs can survive for up to 4 years.

 

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