Plasmacytoma (PLAZ-muh-sy-TOH-muh) is a very rare blood cancer. Fewer than 1,000 people each year are diagnosed with it in the United States. We do not know what causes plasmacytoma.

Plasmacytoma is similar to multiple myeloma. It happens when plasma cells become abnormal, multiply, and make m-protein.

Solitary plasmacytoma is when tumors grow in your bone or bone marrow.

Extramedullary (EK-struh-MED-yoo-LAYR-ee) plasmacytoma (EMP) is when the tumor grows in soft tissues, not in your bones. It’s most common in your head or neck and lungs, but can grow in any soft tissue.

Diagnosing solitary plasmacytoma

There are several kinds of tests that can diagnose solitary plasmacytoma.

Blood and urine tests: These check your level of m-protein.

Imaging tests: These check for damage to soft tissue or bone. You may have a magnetic resonance imaging (MRI), X-ray, or computed tomography (CT) scan.

Learn about the role of imaging in diagnosing cancer.

Biopsy: A biopsy is a procedure to take a sample of tissue or cells. The tumor sample will show plasma cells. We look for myeloma cells to confirm there are no signs of multiple myeloma.

You may have a:

• Bone marrow biopsy, which takes a small sample of bone marrow from your bone.
• Fine needle biopsy, which uses a thin needle, much smaller than ones used to draw blood. It takes a very small sample of cells.

Solitary plasmacytoma treatment

Sometimes we can cure solitary plasmacytoma of the bone with radiation therapy or surgery to kill or remove the tumor. But 7 out of every 10 people with solitary plasmacytoma of the bone get multiple myeloma. They will need chemotherapy.

Extramedullary plasmacytoma treatment

Extramedullary plasmacytoma is when myeloma tumors are in the lungs, throat, or other organs. More than half of people with this condition can be cured with radiation therapy. 

After you have radiation for plasmacytoma, you must have lifelong monitoring. We look for signs of multiple myeloma. If multiple myeloma starts, MSK doctors will treat the disease with chemotherapy and cellular therapies.