Light chain multiple myeloma is a subtype of multiple myeloma, a cancer of the plasma cells in bone marrow. Symptoms can include bone pain, fatigue, infections, swelling, and more.

Multiple myeloma is a rare type of cancer that occurs when plasma cells in bone marrow become cancerous and multiply.

There are different types of multiple myeloma, depending on the type of antibody the plasma cells produce. These antibodies, or immunoglobulins, consist of light and heavy chain proteins.

Light chain myeloma is a subtype of multiple myeloma, in which the immunoglobulins only consist of light chain proteins. This can affect symptoms, treatment types, and outlook.

This article looks at what light and heavy chains are and how light chain myeloma differs from other types of multiple myeloma.

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Multiple myeloma is a rare type of cancer that occurs due to plasma cells becoming cancerous. Plasma cells are a type of white blood cell found in bone marrow, and they help protect against infections.

The term for a cancerous plasma cell is a myeloma cell. These cells can multiply, and excessive plasma cells may group together to form a tumor.

If there are multiple tumors or the bone marrow contains a significant number of cancerous plasma cells, the condition is called multiple myeloma.

Learn more about multiple myeloma here.

There are different types of multiple myeloma. The type depends on the immunoglobulin that a myeloma cell produces, also known as antibodies or M-proteins.

According to the International Myeloma Foundation, immunoglobulins (Ig) usually consist of two heavy chain proteins and two light chain proteins joined together.

Myeloma cells produce abnormal immunoglobulins called monoclonal proteins, or M-spike, which cannot fight infection in the same way as regular immunoglobulins.

There are five types of heavy chain proteins:

  • IgG
  • IgA
  • IgD
  • IgE
  • IgM

There are two types of light chain proteins: kappa and lambda. Light chain proteins are shorter and lighter in weight than heavy chain proteins.

Subtypes of myeloma are categorized based on:

  • the type of immunoglobulins they produce
  • the combination of heavy and light chains the immunoglobulin contains

The types of immunoglobulins are:

  • IgG kappa
  • IgA kappa
  • IgD kappa
  • IgE kappa
  • IgM kappa
  • IgG lambda
  • IgA lambda
  • IgD lambda
  • IgE lambda
  • IgM lambda

The most common type of myeloma is IgG kappa. This means the myeloma cells produce immunoglobulins made of two IgG heavy chains and two kappa light chains.

Roughly 15% of people with multiple myeloma have light chain myeloma.

Light chain myeloma occurs when the myeloma cells only produce immunoglobulins with light chain proteins and no heavy chain proteins.

According to a 2018 article, changes at a DNA level result in an inability to produce any heavy chains, meaning immunoglobulins only have light chain proteins.

People may also refer to light chain myeloma as Bence Jones myeloma after the doctor who discovered this subtype of multiple myeloma.

The most common symptoms of multiple myeloma are:

In addition to multiple myeloma symptoms, people with light chain myeloma may also experience:

  • numbness in limbs
  • loss of appetite
  • impaired kidney function
  • excess calcium in the blood
  • anemia
  • bone damage

A 2018 article found that bone pain and kidney failure are the most common first signs of light chain multiple myeloma.

Learn more about the symptoms of multiple myeloma here.

To diagnose multiple myeloma, doctors will assess any symptoms, take a full medical history, and use a range of tests, including:

  • blood tests to check white and red blood cell counts
  • urine tests to check for elevated levels of M-proteins, as excessive plasma cells can lead to higher levels of M-proteins than usual
  • bone marrow samples to examine plasma cells
  • imaging scans, such as MRI and CT scans, to look for any changes in the bones

These tests can help doctors identify signs that could indicate multiple myeloma, such as:

To diagnose the subtype of multiple myeloma and determine whether a person has light chain myeloma, doctors may:

  • test urine or blood for the presence of light chains
  • check for deposits of light chains in the kidneys or nerves

Light chain multiple myeloma does not create the spike in M-proteins that can be a feature of other types of multiple myeloma, so doctors look for an excess of light chains and the absence of heavy chains.

Learn more about multiple myeloma blood tests here.

Treatment for multiple myeloma may include:

Treatment may vary depending on a person’s overall health, age, and medical history.

According to the Dana-Farber Cancer Institute, doctors usually recommend the following approach to treatment:

  1. initial induction phase
  2. intensified treatment, including an autologous stem cell transplant for people who fit certain criteria
  3. maintenance therapy
  4. treatment for relapsed disease

Doctors often prescribe a VRd drug regimen to treat multiple myeloma. VRd includes:

Learn more about treatment options for multiple myeloma here.

A rare but serious complication of light chain multiple myeloma is light chain amyloidosis. This occurs when large quantities of light chain proteins collect in organs.

Light chain amyloidosis can affect any organ in the body except the brain, and commonly affects the kidneys and heart.

Treatment for light chain amyloidosis may include:

  • diuretics
  • a protein called albumin
  • vasopressors, a type of drug to increase blood pressure to prevent organ damage

Learn more about treatment options for multiple myeloma here.

Having light chain myeloma may affect a person’s outlook compared to other types of multiple myeloma.

According to a 2021 article, impaired kidney function is more common in light chain multiple myeloma than other types of multiple myeloma. This can result in poorer outcomes.

The article notes that bortezomib is an important part of the treatment for managing kidney failure in multiple myeloma.

In a long-term follow-up study of 100 people treated with a VRd drug regimen followed by maintenance therapy, the median survival was around 126 months.

One older 2014 article notes that early diagnosis and treatment play a vital role in improving outcomes for people with light chain multiple myeloma.

If a person has amyloidosis affecting two or more organs, it may also result in a poorer outlook, with an estimated median survival rate of 13 months without treatment. Light chain amyloidosis only occurs in 5–10% of cases.

Learn more about the outlook for multiple myeloma here.

Multiple myeloma is a cancer of the plasma cells found in bone marrow. Light chain myeloma is a subtype of multiple myeloma.

Cancerous plasma cells, or myeloma cells, produce immunoglobulins. These immunoglobulins consist of heavy and light chain proteins.

A person has light chain myeloma if the immunoglobulins from myeloma cells only contain light chain proteins. Light chain myeloma can increase the risk of kidney failure and may result in poorer outlooks than other types of multiple myeloma.

Early diagnosis and treatment, and a treatment regimen with the drug bortezomib help improve a person’s outlook.