Plasmacytoma

A plasmacytoma is a rare form of blood cancer that’s similar to multiple myeloma. Like multiple myeloma, a plasmacytoma happens when plasma cells (healthy, antibody-producing cells normally found in your body) turn into cancer cells. The cells multiply and become a single tumor that forms in your bones or soft tissue.

Most plasmacytomas are treatable. Some are curable with radiation therapy.

But in some people, plasmacytomas come back after treatment. Sometimes, people with this condition develop multiple myeloma. This is a more serious condition that causes additional symptoms.

This is why you’ll need lifelong checkups if you have a plasmacytoma.

​Types of plasmacytoma

There are two types:

• Solitary plasmacytoma of bone (SPB): Abnormal plasma cells form a single tumor in one of your bones. More than half of people with SPB develop multiple myeloma.
• Extramedullary plasmacytoma (EMP): With EMP, a single tumor made of abnormal plasma cells forms in soft tissue. It’s most common in your upper respiratory tract, sinuses and other tissues. Up to 30 out of 100 people with EMP develop multiple myeloma.

Symptoms of plasmacytoma

Symptoms depend on where the tumor is.

SPB symptoms

A plasmacytoma in bone can cause bone pain or fractures. SPB tumors are most likely to form in your spine, pelvis and ribs. But they can form in other bones, too.

EMP symptoms

Symptoms happen when a plasmacytoma presses on soft tissue. Tumors can start wherever you have soft tissue and affect any organ. This includes your liver, lymph nodes, skin and organs in your digestive system. But up to 9 out of 10 people with EMP get tumors in their heads and necks. Common sites include your nasal cavity, sinuses, throat and voice box.

Related EMP symptoms include:

• Headache
• Hoarseness
• Nasal congestion
• Nasal discharge
• Nosebleeds
• Sore throat
• Trouble swallowing
• Signs of a tumor pressing on your spine (back pain, weakness or a pins-and-needles “tingly” feeling in your lower body)

Plasmacytoma symptoms can resemble common problems that may not be signs of cancer. But you should contact your healthcare provider anytime you have symptoms that get worse. Reach out if symptoms last longer than two weeks.

​Plasmacytoma causes

Experts don’t know how healthy plasma cells turn abnormal and form plasmacytomas.

Plasma cells are white blood cells and are part of your immune system. They’re also called B cells. Healthy plasma cells make antibodies. These antibodies fight infections and protect against illnesses. When plasma cells become abnormal, they multiply and produce abnormal antibodies called M proteins. The cancer cells clump together and form a tumor.

Risk factors

People are usually diagnosed in their 50s or 60s. Males are more likely than females to develop this condition. 

People who have multiple myeloma can develop plasmacytomas as part of their disease. So, your risk is greater if you already have this condition.

How doctors diagnose this condition

Healthcare providers use several tests to diagnose plasmacytomas. They include:

• Lab tests: Healthcare providers do lab tests to measure M protein levels. They’ll check for problems with your blood cells.
• Imaging tests: CT scans show signs of SPB, while MRIs can show signs of EMP. You may need a whole-body PET/CT or a whole-body MRI to check for tumors throughout your body.
• Nasal endoscopy: Providers may use this scope test to look for tumors inside your nose and sinuses.
• Biopsy: Your provider will remove samples of fluid and tissue from the tumor and your bone marrow. They’ll test the samples for abnormal plasma cells.

Plasmacytoma vs. multiple myeloma

An important part of diagnosis is making sure a plasmacytoma isn’t a sign of multiple myeloma. The cancer cells in these conditions are the same. But plasmacytoma is less advanced. It requires different treatments.

With a plasmacytoma:

• You only have one tumor that contains the abnormal plasma cells.
• You don’t have multiple myeloma symptoms. For instance, you don’t have kidney problems or anemia that’s linked to the plasma cells.
• You don’t have abnormal plasma cells in your bone marrow. (With multiple myeloma, more than 10% of the cells in your bone marrow are abnormal plasma cells.)

There’s an important exception. You can get a plasmacytoma diagnosis if less than 10% of cells in your bone marrow are abnormal plasma cells. Providers call this “solitary plasmacytoma with minimal bone marrow involvement.” 

Having “minimal bone marrow involvement” means you don’t have multiple myeloma. But you’re at a greater risk of developing it than someone who doesn’t have any cancer cells in their bone marrow.

How is it treated?

Healthcare providers treat plasmacytomas with radiation therapy. Treatment usually takes place in sessions that span several weeks. This treatment often cures SBP.

Sometimes, people need surgery first. For instance, you may need surgery if a tumor is making a bone unstable or if it affects other organs. Your provider may recommend radiation after surgery.

You may need treatments that kill cancer cells throughout your body if your provider thinks your risk of developing multiple myeloma is high. Options include chemotherapy and immunotherapy. Many people with plasmacytomas are now treated with immune therapies as if they have multiple myeloma. This is to prevent the plasmacytoma from growing or invading other parts of the body.

Studies show high cure rates for some people when immunotherapy is used early.

When should I see my healthcare provider?

Your care team will follow up with you after treatment. You’ll likely need regular imaging and bloodwork. Follow-ups are often more frequent in the first year after treatment. But you’ll need follow-up monitoring for the rest of your life.

If the plasmacytoma comes back or you develop multiple myeloma, you’ll discuss a new treatment plan with your provider.

What is the life expectancy of someone with a plasmacytoma?

According to a recent study, approximately 77% of people who have SBP are alive five years after diagnosis. Approximately 81% of people who have EMP are alive five years after diagnosis.

Still, life expectancy is hard to predict. This depends on the type of plasmacytoma, the genetics of the tumor and how you respond to treatment.

For instance, radiation therapy cures this condition in many people. In this case, you may live as long as someone without this condition.

Is there anything I can do to feel better?

No matter how treatment goes, you’ll need lifelong follow-up care after. This is why one of the best things you can do to ease your mind is to understand what comes next.

Follow-up care often includes regular blood and imaging tests. But your care plan depends on factors unique to you.

Ask your healthcare provider what to expect.