Types of myeloma

IgG myeloma

Approximately 65% of myeloma patients have what is called IgG type myeloma. This means that the immunoglobulin is made up of two IgG heavy chains and either two kappa or two lambda light chains. IgG kappa is slightly more common than IgG lambda.

IgA myeloma

The next most common type is IgA myeloma with either kappa or lambda light chains whereas IgM, IgD and IgE type myeloma are all quite rare.

Light chain myeloma

In approximately 20% of patients, the myeloma cells produce only light chains and no heavy chains at all. This is known as ‘light chain’ or ‘Bence Jones’ myeloma.

Non-secretory myeloma

In rare cases, myeloma cells secrete very little or no immunoglobulins or free light chains. This occurs in approximately 2% of patients and is called ‘non-secretory myeloma’. This makes diagnosis and monitoring very difficult; however, a test has been developed that measures free light chains in the blood called the Serum Free Light Chain Assay (SFLCA). This test can detect minute amounts of light chains in the serum in most ‘non-secretory’ patients and has therefore improved diagnosis and monitoring. It is treated in much the same way as secretory myeloma.

Some research has shown subtle differences in the behaviours of the different types of myeloma. For example, IgG, the most common type, normally has all the usual features of myeloma; on the other hand, IgA myeloma can sometimes be characterised by tumours outside the bone. Light chain or Bence Jones myeloma is the most likely to cause kidney damage and can lead to deposits of the light chain component in the kidneys, nerves or other organs, resulting in conditions such as AL amyloidosis or light chain deposition disease (LCDD).

As myeloma is a heterogeneous disease, it is important that each patient is assessed and treated on an individual basis to ensure they receive optimal treatment and care.