Plasma cell tumors in dogs are relatively rare but significant to diagnose, particularly since they can vary from benign to possibly malignant. As an owner of a pet, knowing about these tumors can assist you in making early decisions that can have a dramatic effect on the health and well-being of your dog.
What Is a Plasma Cell Tumor?
Plasma cells are white blood cells that are derived from B-cells, which are vital to the immune system. Plasma cells secrete antibodies that are used by the body to combat infection. The plasma cell tumor (PCT) results from these cells growing out of control and creating a mass. In dogs, the tumors are:
- Extramedullary (outside of bone marrow) – most prevalent
- Bone marrow-based, which is one component of a systemic condition known as multiple myeloma
Common Sites in Dogs
Plasma cell tumors may occur in many areas of a dog’s body, most often:
- Skin (cutaneous PCTs) – frequently on the head, legs, or trunk
- Mouth – like the gums or hard palate
- Mucocutaneous junctions – where mucous membranes meet skin (e.g., lips, anus, vulva)
- Less often in abdominal organs or bone marrow
Are Plasma Cell Tumors in Dogs Malignant?
The character of plasma cell tumors is different:
- Benign (plasmacytomas): The majority of skin and oral tumors belong to this category. They are typically well-defined and non-metastasizing.
- Malignant: PCTs occasionally become aggressive and metastasize to other parts of the body in a few instances, particularly when they occur internally.
Symptoms to Watch For
Symptoms vary with tumor location and size. Typical presentation includes:
- A skin or oral growth or lump
- Ulceration or bleeding from the tumor
- Chewing or eating difficulty (if oral)
- Swelling or pain
- Lameness or bone pain (if there is bone involvement)
In systemic disease such as multiple myeloma, additional signs may be lethargy, weight loss, increased drinking and urination, or bone fractures.
Diagnosis
Veterinary diagnosis usually includes:
- Physical Examination
- Fine-needle aspirate or biopsy – to obtain cells for cytology or histopathology
- Blood tests – to look for evidence of systemic disease or organ compromise
- Imaging – for example, X-rays or ultrasound to evaluate internal involvement
- Bone marrow aspirate – in cases of suspected multiple myeloma
Treatment Options
Treatment is based on whether or not the tumor is localized or within a systemic disease:
- Surgical Removal: The initial treatment for most local plasma cell tumors. Surgery usually cures oral and cutaneous plasmacytomas.
- Radiation Therapy: Employed where tumors are resistant to surgical removal or are removed incompletely.
- Chemotherapy: Most often for multiple myeloma or aggressive tumors with metastasis. Drugs such as melphalan and prednisone are used.
- Immunotherapy/Targeted Therapy: Currently under investigation but potentially promising in the future.
Prognosis
- Localized benign neoplasms: Prognosis is ideal with complete surgical resection.
- Multiple myeloma or malignant neoplasms: Prognosis depends on response to therapy. Many dogs can survive months to years with proper therapy.
Prevention and Monitoring
There’s no method known to prevent plasma cell tumors, but an early discovery is important. Annual vet check-ups and monitoring any new lumps or behavioral modifications in your dog can help a lot.
Dog Plasma Cell Tumors – FAQs
A plasma cell tumor is a growth caused by the uncontrolled multiplication of plasma cells — immune cells that produce antibodies. These tumors can occur on the skin, in the mouth, or internally.
Most plasma cell tumors in dogs are benign (non-cancerous), especially when they appear on the skin or in the mouth. However, in some cases (such as multiple myeloma), they can be malignant and spread to other areas.
The exact cause is unknown. Some contributing factors may include genetics, chronic inflammation, or immune system dysregulation. Certain breeds may be more prone.
Benign plasmacytomas usually don’t spread. However, malignant forms like multiple myeloma can affect bones, organs, and blood cells and require more aggressive treatment.
Yes, recurrence can happen, especially if the tumor wasn’t completely removed. Regular monitoring and follow-up with your vet are essential.
Final Thoughts
Plasma cell tumors in dogs are most often benign, particularly when they are on the skin or in the mouth. They should always be checked by a veterinarian, however, to decide what to do. With proper diagnosis and treatment, many dogs live healthy, happy lives.
If you’re worried about a lump on your dog or noticing unusual symptoms, don’t wait—schedule a veterinary appointment. The sooner you act, the better the outcome.
