Plasmacytoma

Learn about this rare plasma cell cancer, including its types, symptoms, diagnosis and treatment. Understand survival rates and the risk of the disease changing into multiple myeloma.

Update Date: 01.09.2026

Overview
Symptoms
Causes
Risk factors
Complications
Diagnosis
Treatment
Coping and support
Preparing for an appointment

Overview

Plasmacytoma is a rare cancer that forms in a type of white blood cell called a plasma cell. Healthy plasma cells help the body fight infections by making proteins called antibodies.

In plasmacytoma, cancerous plasma cells grow out of control and form a tumor. The tumor usually forms in a bone. Less often, it forms in soft tissue outside the bones.

Plasmacytoma is related to multiple myeloma, but the two conditions are different. Plasmacytoma usually involves one tumor in one place in the body. Multiple myeloma is more widespread. It affects plasma cells in the bone marrow throughout the body rather than forming just one tumor in one place. Sometimes, plasmacytoma can become multiple myeloma over time.

Plasmacytoma is not the same thing as plasmacytosis. These are two different medical conditions that can be easy to mix up. Plasmacytoma refers to plasma cell cancer. Plasmacytosis means there is an increased number of plasma cells in the blood or bone marrow.

Reactive plasmacytosis happens when the body makes more plasma cells in response to another health condition. This can happen with an infection or an autoimmune disease, which causes the immune system to attack healthy cells and tissues. Reactive plasmacytosis isn't cancer.

Treatment for plasmacytoma may cure it. But sometimes the cancer comes back or changes into multiple myeloma. This change is called progression. Regular follow-up care after plasmacytoma treatment can help find these changes.

There are two main types of plasmacytoma. The type depends on where the tumor starts.

  • Solitary plasmacytoma of bone. This is the more common type. It starts in a bone and may grow into soft tissue nearby. Solitary plasmacytoma of bone most often affects the spine. Other common places where a tumor can form include the pelvis, ribs and skull.
  • Extramedullary plasmacytoma. This type starts in soft tissue outside the bones. It most often starts in the head or neck, such as in the nose, sinuses or throat. It can start in other parts of the body too. Another name for this type is extraosseous plasmacytoma.

A plasmacytoma that starts in a bone may grow into nearby soft tissue. If this happens, it's still a solitary plasmacytoma of bone. It isn't an extramedullary plasmacytoma.

Rarely, an extramedullary plasmacytoma can occur in the skin.

Symptoms

Plasmacytoma symptoms depend on where the tumor is.

Plasmacytoma in a bone often causes pain in the affected area. Other symptoms may include swelling or a lump over or near the affected bone. You also could have a broken bone.

A plasmacytoma in the spine can press on the spinal cord or nearby nerves. This may cause numbness, tingling or weakness in the arms or legs.

Symptoms of extramedullary plasmacytoma depend on where tumors grow. Because these tumors often occur in the head and neck, symptoms may include:

  • A blocked or stuffy nose.
  • Nosebleeds.
  • Trouble swallowing.
  • A hoarse voice.
  • A lump you can see or feel in your head or neck.

Extramedullary plasmacytomas in other parts of the body can cause different symptoms depending on where the tumor grows.

Make an appointment with a doctor or other healthcare professional if you have symptoms that worry you.

Seek emergency medical care if you have plasmacytoma and develop new or worsening:

  • Weakness in your arms or legs.
  • Trouble walking.
  • Numbness, tingling or loss of feeling in your arms or legs.
  • Loss of bladder or bowel function.

These may be signs that a tumor in the spine is pressing on the spinal cord.

Causes

It's not clear what causes plasmacytoma. Researchers have found changes in the genes of plasmacytoma cells. It's not known whether these changes can be passed down in families.

Plasmacytoma happens when a plasma cell turns into a cancer cell. Healthy cells grow and divide based on what the body needs. Old or damaged cells die and are replaced. Cancer cells don't follow these rules. The cells continue living when healthy cells would die. In plasmacytoma, cancer cells multiply out of control and build up in one place, forming a tumor.

Experts don't know why some people with changes in plasma cells develop a single plasmacytoma while others develop multiple myeloma.

Risk factors

There aren't many known risk factors for plasmacytoma. Plasmacytoma is more common in some groups of people. Factors linked with plasmacytoma include:

  • Older age. Plasmacytoma is most often diagnosed in middle-aged and older adults. It's rare before age 40.
  • Sex at birth. Plasmacytoma occurs about twice as often in men as in women.
  • Race. In the United States, plasmacytoma occurs more often in Black people than in white people. It occurs least often in Asian Americans and Pacific Islanders.
  • A weakened immune system. The risk of plasmacytoma is higher in people with weakened immune systems. This is especially true for people who have received organ transplants, such as kidney, liver, heart or lung transplants.

Researchers haven't found evidence that environmental factors increase the risk of plasmacytoma.

Complications

Plasmacytoma can cause complications when a tumor damages a bone or presses on nearby tissues. Possible complications include:

  • Broken bones. A plasmacytoma in a bone can weaken the bone and cause it to break.
  • Pressure on the spinal cord or nerves. A plasmacytoma in the spine can press on the spinal cord or nearby nerves. This can cause weakness, numbness, tingling or trouble walking.
  • Pressure on nearby tissues or organs. An extramedullary plasmacytoma can press on or block nearby structures. The complications depend on where the tumor grows.

Diagnosis

Diagnosing plasmacytoma takes several tests. Your care team needs to confirm that the tumor is a plasmacytoma. The team also needs to find out whether cancerous plasma cells are in your bone marrow or whether there are other tumors in your body.

A biopsy is used to confirm plasmacytoma. During a biopsy, a healthcare professional removes a sample of tissue for testing in a lab. The sample is checked for cancerous plasma cells. A computerized tomography (CT) scan or magnetic resonance imaging (MRI) may be used to guide the biopsy.

Along with a biopsy, other tests look for cancerous plasma cells in your bone marrow and tumors in other parts of your body. The results help your care team tell the difference between plasmacytoma and multiple myeloma. This is important because the two conditions are treated differently.

The goal of testing is not only to confirm plasmacytoma. It is also to make sure there isn't evidence of multiple myeloma anywhere else in the body.

Tests may include:

  • Blood tests. Blood tests can check your blood cell counts, calcium levels and how well your kidneys are working. Other blood tests look for proteins made by the cancerous plasma cells. These proteins are called monoclonal proteins (M proteins).
  • Urine tests. Urine tests also can look for M proteins. You may need to collect your urine over 24 hours for testing.
  • Bone marrow tests. Bone marrow biopsy and bone marrow aspiration are procedures to collect and examine bone marrow. The tests look for cancerous plasma cells in your bone marrow. These tests are done after the first biopsy that confirms the tumor is plasmacytoma. Results of these tests help your care team understand how widespread your condition may be.
  • Imaging tests. Whole-body MRI or a PET scan combined with a CT scan, called PET-CT, can look for other tumors or changes in the bone marrow. Finding other areas of concern can mean that the condition is multiple myeloma rather than solitary plasmacytoma. Regular X-rays may not find all the changes that can show whether a person has multiple myeloma.

Bone marrow is the soft tissue inside some bones where blood cells are made. Sometimes, bone marrow testing finds a small number of cancerous plasma cells even when imaging shows only one tumor. When less than 10% of the cells in the bone marrow are cancerous plasma cells, the condition is called solitary plasmacytoma with minimal bone marrow involvement. This condition is different from a solitary plasmacytoma in which no cancerous plasma cells are found in the bone marrow.

Plasmacytoma stages

There is no standard staging system for plasmacytoma. Instead, the tests used for diagnosis help show whether there is one tumor. Or they may show evidence of a more widespread plasma cell cancer, such as multiple myeloma.

Treatment

Treatment for plasmacytoma usually aims to control the tumor or get rid of it. Most plasmacytomas are treated with radiation therapy. Surgery may be used sometimes. The type of treatment you have depends on whether the tumor starts in a bone or in soft tissue outside the bones.

Solitary plasmacytoma of bone

Radiation therapy is the main treatment for a tumor that starts in a bone, called solitary plasmacytoma of bone. Radiation therapy uses high-energy beams to kill cancer cells. Plasmacytomas are sensitive to radiation. This means radiation therapy can often control or get rid of the tumor in the area being treated.

Radiation is directed at the tumor and the area around it. The amount of radiation and the area treated depend on how big the tumor is and where it's located.

You may need surgery if the tumor has weakened a bone or is pressing on the spinal cord or nerves. Surgery can help stabilize the bone or relieve pressure. Surgery doesn't replace radiation therapy for treating this type of plasmacytoma.

Extramedullary plasmacytoma

Radiation therapy also is a main treatment for a tumor that starts in soft tissues outside the bones, called extramedullary plasmacytoma. The treatment is directed at the tumor and the area around it.

Surgery may be used for some people when the tumor can be taken out. Radiation therapy often is still part of treatment. In selected cases, such as some tumors in the upper or lower airway, surgery alone may be an option.

Medicines

Medicines that treat cancer throughout the body, called systemic therapy, aren't usually used to treat plasmacytoma. Researchers are studying whether adding medicines to radiation therapy may help some people with solitary plasmacytoma who have a higher risk of developing multiple myeloma.

If plasmacytoma becomes multiple myeloma, treatment changes. You may then need to take medicines that are used to treat multiple myeloma.

Follow-up care

Regular follow-up care is important after treatment. Plasmacytoma can return or become multiple myeloma, sometimes years after treatment. Follow-up may include blood and urine tests along with imaging tests to look for changes.

Follow-up visits happen at regular intervals based on your care team's recommendations. For example, you may have follow-up visits every three months for the first two years after your first treatment. Then you may go back every six months for the next three years, followed by yearly visits after that. Your care team watches for any complications from treatment or signs that your cancer has returned.

Coping and support

Being diagnosed with plasmacytoma can bring uncertainty, especially because this cancer may be treated successfully but still needs long-term follow-up. You may worry about treatment, test results, or the chance that plasmacytoma could come back or become multiple myeloma.

These steps may help you cope with plasmacytoma:

  • Understand your diagnosis. Ask your care team what type of plasmacytoma you have, where the tumor is and whether any tests show cancerous plasma cells in your bone marrow.
  • Ask about your follow-up plan. Find out how often you need to have blood tests, urine tests or imaging tests after treatment. Also ask which results might lead to more testing or treatment.
  • Keep track of important information. Keeping copies of your biopsy, bone marrow, blood, urine and imaging test results may help you feel more prepared for follow-up visits or visits with new specialists.
  • Prepare for treatment and recovery. If you need radiation therapy or surgery, ask what side effects to expect, how treatment could affect daily activities and when to call your care team.
  • Get emotional support. Talk with a trusted friend, counselor, social worker or mental health professional if worry affects your sleep, mood or daily activities.
  • Ask for help from others. Invite someone you trust to come with you to appointments, help keep track of information, or support you during treatment and follow-up.

Preparing for an appointment

If you have symptoms that could be caused by plasmacytoma, you may start by seeing your usual healthcare professional. You may then be referred to a doctor who specializes in blood conditions, called a hematologist, or a doctor who specializes in treating cancer, called an oncologist.

Here's some information to help you get ready for your appointment.

What you can do

When you make the appointment, ask if there's anything you need to do ahead of time. Also:

  • Write down your symptoms. Make note of when they started and whether they have changed over time.
  • Write down important health information. Gather details about any other health conditions you have.
  • Make a list of medicines you take. Include prescription and nonprescription medicines, vitamins and supplements. Also write down the amount, called the dose, that you take.
  • Bring a family member or friend, if possible. Someone who comes with you can help you remember what your healthcare professional tells you.
  • Write down questions to ask. Put your most important questions first in case time runs short.

For plasmacytoma, questions you may want to ask include:

  • What type of plasmacytoma do I have?
  • Where is the tumor?
  • What tests do I need?
  • Have you found cancerous plasma cells in my bone marrow?
  • Do my test results show any signs of multiple myeloma?
  • What treatment do you recommend?
  • Will I need radiation therapy?
  • Will I need surgery?
  • What side effects might treatment cause?
  • What is the chance that treatment will get rid of the plasmacytoma?
  • What is the chance that the plasmacytoma will return or become multiple myeloma?
  • What follow-up tests will I need?
  • How often will I need follow-up visits?
  • What symptoms should I report right away or seek emergency care for?
  • Should I see a doctor who specializes in plasma cell cancers?
  • Are there brochures or other printed materials I can take with me? What websites do you recommend?

Don't hesitate to ask other questions you may have.

What to expect from your doctor

Your healthcare professional is likely to ask you questions. These may include:

  • What symptoms do you have?
  • When did your symptoms start?
  • Have your symptoms changed over time?
  • Where do you have pain?
  • Have you noticed a lump or swelling?
  • Have you had numbness, tingling or weakness?
  • Have you had trouble walking?
  • Have you had any broken bones?
  • Do you have any other health conditions?
  • What medicines, vitamins and supplements do you take?

© 2026 Mayo Foundation for Medical Education and Research. All rights reserved. Terms of Use