Types of Myeloma

Myeloma is often described as being a very individual disease; both in terms of the way patients experience complications and in the way they respond to treatment, all of which can vary greatly. Some of this variation is due to the different types and sub-types of myeloma.

Each individual immunoglobulin (Ig for short), can have only one of the five possible heavy chain types and only one of the two possible light chain types.

Most people with myeloma, about 65%, have what is called IgG type myeloma.

 That is immunoglobulin type G (one of the five possible heavy chains), with either the kappa or lambda light chain component.

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

At the same time as producing one whole immunoglobulin structure, approximately 30% of patients will also produce light chains (such as kappa light chains) on their own which are detectable in the urine rather than in the blood.These excess 'light chains' are also known as 'Bence Jones' protein.

In about 20% of patients, the myeloma cells produce light chains only (no heavy chains at all). This is called 'light chain' or 'Bence Jones' myeloma.

More rarely, in about 1-2% of cases, the myeloma cells produce very little or no immunoglobulin of any type which is known as 'non-secretary myeloma' making diagnosis and monitoring very difficult. However, a recently developed test called the Freelite™ test has been able to detect minute amounts of light chains in the urine in most of the traditionally labelled 'non-secretary' patients, therefore making diagnosis and monitoring easier. 

Different types and sub-types of myeloma are based on the type of immunoglobulin (paraprotein) produced by the myeloma cell.

Each immunoglobulin is made up of a specific structure containing two principle components, heavy chains of which there are two and light chains of which there are also two (see Figure 2).

There are five possible types of heavy chain component denoted by the letters G, A, D, E and M, and there are two possible types of light chain component denoted by the Greek letters, Kappa (k) and Lambda (l).