Types of myeloma
There are different types and subtypes of myeloma. These include:
- light chain myeloma
- non secretory myeloma
- myeloma without symptoms (smouldering myeloma)
There are also some other conditions related to myeloma. For example, MGUS, plasmacytoma and amyloidosis. Some of these conditions can develop into myeloma.
To understand about the different types of myeloma, it is helpful to know about plasma cells, paraproteins and immunoglobulins.
Plasma cells, immunoglobulins, paraproteins and myeloma
In myeloma, the bone marrow makes lots of abnormal (cancerous) 
.
Normal plasma cells make proteins called that protect us from infection. These antibodies are also called immunoglobulins.
The abnormal plasma cells (myeloma cells) make abnormal types of antibodies (immunoglobulins) called . Doctors use different names for paraproteins. They might also call them:
- abnormal proteins
- monoclonal proteins
- myeloma proteins
- a monoclonal spike.
Each paraprotein is made up of:
- 2 long protein chains - these are also called heavy chains
- 2 shorter protein chains – these are also called light chains
This is important because sometimes the myeloma doesn’t make the whole paraprotein. It sometimes only makes large amounts of the light chain part of the paraprotein. These are called free light chains or Bence Jones proteins.
Light and heavy chains
There are different types of heavy and light chains. These are described below:
- Heavy chain - there are 5 types, G, A, D, E and M
- Light chain – there are 2 types, kappa and lambda
The types of myeloma
Your myeloma will only make one type of paraprotein (so either G,A,D,E or M). Your doctor names your myeloma after the type of:
- abnormal immunoglobulin (paraprotein) it is making (G, A, D, E or M)
- light chain (kappa or lambda)
Based on this your doctor might say you have, for example, IgG kappa myeloma.
IgG myeloma, is the most common type, followed by IgA myeloma. IgM, IgD and IgE are very rare.
There are other subtypes of myeloma, which we describe below:
Light chain myeloma (Bence Jones myeloma)
About 15 out of 100 people with myeloma (15%) have light chain myeloma. This means their myeloma cells only produce the light chain part of the immunoglobulin. They do not produce the heavy chain part.
Doctors call this Bence Jones myeloma after the doctor who discovered it. There is a urine test which can detect the light chains (Bence Jones protein) in your urine.
A blood test can also pick up small increases in the amount of free light chains in the blood. This is called a serum free light chain test. Doctors use this test to:
- measure the amount of each of the light chains in your blood
- to compare the amount of kappa light chains to the amount of lambda light chains – this is known as the ratio
Your doctor can use the test to diagnose and monitor your myeloma.
Non secretory myeloma
In around 3 out of every 100 people with myeloma (around 3%), the myeloma cells produce little or no paraprotein. This makes it harder to diagnose and monitor. Doctors call this non secretory myeloma.
Doctors use bone marrow tests and scans (such as PET-CT) to diagnose and monitor non secretory myeloma.
Myeloma without symptoms (smouldering myeloma)
Asymptomatic myeloma is also called smouldering or indolent myeloma. This means you don't have symptoms or any tissue or organ damage.
But you have one or more of these:
- paraprotein in your blood that is more than 30 g/L
- level of abnormal plasma cells in your bone marrow that is between 10% and 60%
- no features of CRAB (including bone lesions on scans that are not causing symptoms)
- low light chain levels in your blood or urine
You don't normally have treatment for smouldering myeloma. But your doctor will want to monitor you very regularly for any symptoms. Smouldering myeloma may progress to symptomatic myeloma, but your doctor won't be able to say when this will happen. The risk of myeloma progressing is highest in the first 5 years after diagnosis.
About 50 out of 100 people (50%) with smouldering myeloma develop symptoms and need treatment within the first 5 years. However, after 5 years the risk decreases and some people never develop symptoms or need treatment.
Types of myeloma depending on gene changes
Myeloma develops when there is a change in the of the plasma cells. Genes are the instruction manuals for cells ‘telling’ them how to behave. There are subtypes of myeloma based on the gene changes in the myeloma cells.
Knowing the genetic subtype can help doctors know how your myeloma might progress. Doctors are doing research to understand more about these genetic subtypes. In the future, treatment options might vary, depending on your genetic subtype.
Your doctors usually do tests on your blood and bone marrow to look for changes in certain genes. You might hear these tests called cytogenetic tests or molecular analysis.
The doctors give mutations names which are codes for the specific change. They refer to these genetic mutations as either high risk or low risk. They use this information, along with other factors, to decide what stage your myeloma is. This helps them understand how your myeloma might develop.
Other conditions related to myeloma
These are conditions that also affect plasma cells, and are related to myeloma:
- monoclonal gammopathy of undetermined significance (MGUS)
- plasmacytoma
- amyloidosis
Monoclonal gammopathy of undetermined significance (MGUS)
MGUS is not cancer. But some people with it can go on and develop myeloma. If you have MGUS, your plasma cells make too many abnormal immunoglobulins. Doctors call these paraproteins or M protein. These show up in your blood test.
For most people, this doesn’t cause symptoms or affect your health. MGUS is often found by chance, in blood tests for a routine check up.
Doctors might diagnose MGUS if they find paraprotein in your blood. They look at the level of the paraprotein and do other tests to rule out other conditions like myeloma. They diagnose MGUS if:
- the level of abnormal paraprotein in your blood is less than 30 g/l
- the level of abnormal plasma cells in your bone marrow is less than 10%
- there is no evidence of certain other related conditions
- there are no related problems with organs or tissues
MGUS does not usually need treatment. Some people with MGUS go on to develop myeloma, so your specialist or GP will see you regularly for check ups. About 1 out of 100 people with MGUS (1%) develop myeloma each year.
Plasmacytoma
A plasmacytoma is similar to myeloma. But the abnormal plasma cells are in one place and form a lump (tumour). You can develop a plasmacytoma in bone or soft tissue.
You might have:
- one area of plasmacytoma - a solitary plasmacytoma
- more than one plasmacytoma - multiple solitary plasmacytomas
Plasmacytoma can develop in the bone, or outside the bone in the soft tissue. A plasmacytoma outside the bone is called an extramedullary plasmacytoma.
More than 50 out of 100 (more than 50%) of people with bone plasmacytoma go on to develop myeloma later in life. Soft tissue (extramedullary) plasmacytoma can also develop into myeloma but is less common.
Doctors usually treat plasmacytoma with .
Amyloidosis
This is a rare conditon. The plasma cells make an abnormal protein called amyloid. The amyloid collects in body organs, such as the kidneys or heart, and gradually causes damage.
About 10 to 15 out of every 100 people with myeloma (10 to 15%) develop amyloidosis. But it doesn't always cause problems. However, it is rare for people with amyloidosis to develop myeloma.
Doctors usually treat amyloidosis with chemotherapy, and use the same drugs that you would have for myeloma.
