Plasmacytoma and multiple myeloma (MM) are two types of cancer that affect plasma cells. There are several differences between these two types of cancer. Many people with plasmacytoma go on to develop MM.
Plasma cells are a type of white blood cell. They normally function by making antibodies to help defend you against germs such as viruses and bacteria.
Sometimes, cancer can affect plasma cells. Two examples of this are plasmacytoma and multiple myeloma (MM). While these conditions are both plasma cell cancers, there are also key differences to be aware of.
Plasma cell cancers happen when plasma cells begin growing and dividing out of control. When this happens, they can form tumors.
A plasmacytoma is a plasma cell tumor that can form in the bone or in the soft tissues of your body. Read more about plasmacytoma.
Multiple myeloma (MM) is when a dysfunctional form of plasma cells develops in your bone marrow and reproduces quickly, crowding out the production of other important blood cells produced by your bone marrow.
In addition to growing uncontrollably, the dysfunctional plasma cells, and to a lesser extent, plasmacytoma, produce an abnormal antibody called M protein. High concentrations of M protein can cause health complications.
While plasmacytoma and MM do have similarities, they also have key differences in things such as:
We review in more detail each of these key differences below.
Tumors: Number and location
Generally speaking, the cancer cells in a plasmacytoma typically form a tumor at a single location. This is called a solitary plasmacytoma.
There are two types of plasmacytomas:
- Solitary plasmacytoma of the bone (SPB): SPB occurs in a bone,
most commonlythose of your spine, ribs, or skull. The incidence of SPB is 40% higherthan that of extramedullary plasmacytoma.
- Extramedullary plasmacytoma (EMP): EMP happens in soft tissue. It’s
most often foundin the head and neck area, such as your throat, sinuses, and tonsils.
In contrast, abnormal growths of plasma cells in MM can be found in the bone marrow of many bones in your body. Unlike plasmacytomas, they’re not found in soft tissues.
In MM, cancer cells build up in your bone marrow. This crowds out healthy blood cells, leading to low blood counts that can cause:
- an increased risk of infections
- easy bleeding
The effects of MM also cause characteristic organ damage throughout the body. These are referred to as “CRAB symptoms” and include:
- C: Calcium elevation in the blood (hypercalcemia) due to bone damage.
- R: Renal (kidney) disease related to M protein and hypercalcemia.
- A: Anemia because of low red blood cell levels.
- B: Bone disease with symptoms such as bone pain, weakness, and easy breaks.
While many of the diagnostic tests for plasmacytoma and MM are similar, each condition has different diagnostic criteria. This is a set of symptoms, signs, or test results used to accurately diagnose a condition.
Plasmacytoma can be diagnosed when
- A lesion of abnormal plasma cells is found in the bone or in soft tissue.
- The abnormal plasma cells are clonal, meaning that they’re derived from a common ancestor cell.
- Bone marrow is normal or contains less than 10% cancer cells.
- A skeletal survey is normal, aside from the original lesion.
- There’s no evidence of CRAB symptoms.
Meanwhile, MM is diagnosed when
- A clonal, or duplicate, population of abnormal plasma cells of 10% or more in the bone marrow or a biopsy-confirmed plasmacytoma is present.
- Any one or more of the following things are true:
- There’s evidence of CRAB symptoms.
- More than one bone lesion is found using imaging.
- There’s a population of clonal plasma cells in your bone marrow at 60% or more, with or without CRAB symptoms.
- Your serum free light chain ratio is elevated, and the concentration of free light chain is 100 milligrams per liter (mg/L) or higher.
Staging is a reflection of the extent of the cancer in your body. There’s
- Beta-2-microglobulin (B2M): B2M is found on the surface of plasma cells and is at higher levels in MM.
- Albumin: Albumin is an important protein found in blood plasma. It’s found at lower levels in MM.
- Lactate dehydrogenase (LDH): Elevated LDH levels can signal tissue damage and more advanced MM.
- Genetics: Certain genetic changes in MM are associated with a poorer outlook for people with cancer.
|Stage 1||B2M levels are less than 3.5 mg/L, albumin levels are 3.5 grams per deciliter (g/dL) or higher, LDH levels are normal, and genetics aren’t high risk.|
|Stage 2||This isn’t stage 1 or 3.|
|Stage 3||B2M levels are 5.5 mg/L or higher, LDH levels are high, or cytogenetics are high risk.|
People with smoldering MM often don’t require treatment immediately. Instead, they’re monitored carefully, and treatment begins when symptoms develop. Some people with smoldering MM never develop active MM.
Active MM can be treated using one or a combination of therapies. These may include:
- targeted therapy
- immunotherapy, which can include:
- stem cell transplant
Radiation therapy can also be used to ease bone pain from MM. This is called palliative care. Additionally, radiation therapy and surgery can also be used to prevent serious complications from spinal cord compression in MM.
Now let’s explore the different aspects of progression for plasmacytomas and MM.
The outlook for people with plasmacytoma is typically very good when treatment is given. For example, radiation therapy for plasmacytoma can result in a control rate of
But plasmacytoma can progress into MM. This is more common in SPB than in EMP. A
Some factors that are associated with a poorer outlook for people with plasmacytoma
- older age
- larger tumor size
- SPB that affects your spine
- clonal abnormal plasma cells found in your bone marrow
- M protein that persists after treatment
As such, individuals treated for plasmacytoma will need regular follow-ups to check on the recurrence or the development of MM.
If you have smoldering MM, your risk of progression to active MM is about
People with MM can also develop both SPB and EMP. It’s estimated that
- the stage of your MM
- the genetics of your MM
- the type of treatment used and how your MM responds to it
- your level of kidney function
- your age and overall health
Plasmacytoma and MM are both cancers that affect plasma cells. But these cancers have many differences in things such as basic characteristics, symptoms, diagnosis, and treatment.
Generally, the outlook for people with plasmacytoma is good. Many people eventually do go on to develop MM sometime in the future. While MM is very treatable, it typically can’t be cured.