Plasma cell leukemia (PCL) is a rare, aggressive subtype of multiple myeloma. Between 1973 and 2009, it’s estimated that PCL made up 0.6 percent of multiple myeloma diagnoses in the United States. This is about 1,200 new diagnoses each year.

In PCL, high numbers of plasma cells are found in the blood and bone marrow. Plasma cells are antibody-producing immune cells that develop from activated B cells. There are two types of PCL: primary and secondary.

Primary PCL is a newly diagnosed blood cancer, making up 60 to 70 percent of PCL diagnoses. It has different genetic and molecular markers to secondary PCL. The average age at diagnosis is 61, about 10 years younger than multiple myeloma.

Secondary PCL is when multiple myeloma transforms into PCL. It makes up 30 to 40 percent of PCL diagnoses. Secondary PCL has been increasing, likely due to advances in multiple myeloma treatment. The average age at diagnosis is 66.

Multiple myeloma also affects plasma cells. In multiple myeloma, as in PCL, plasma cells grow and divide out of control.

However, in multiple myeloma, abnormal plasma cells remain confined to the bone marrow. In PCL, these cells spread out into the bloodstream.

Traditionally, PCL is defined by the number of plasma cells circulating in the blood. These criteria can include:

  • plasma cells that make up over 20 percent of circulating white blood cells
  • a plasma cell count of over 2×109 cells per liter in the blood

However, it’s also possible that lower cutoffs for plasma cell numbers can be used to diagnose PCL. Genetic and molecular analyses may also be performed.

The exact cause of PCL is unknown. Similar to other cancers, PCL develops due to a series of genetic changes whose presence can lead to the emergence of abnormal cells that grow and divide out of control.

What exactly triggers these genetic changes to occur is unknown. Additionally, the mechanism by which abnormal plasma cells escape from the bone marrow and enter the bloodstream is also unclear.

According to UK’s Leukemia Care, a few known factors for PCL are:

  • PCL appears to occur twice as often in people of African descent compared to white people.
  • PCL also appears to be slightly more common in those assigned male at birth compared to those assigned female, though this distribution was more balanced in recent studies on primary PCL.

The exact reasons for these differences are currently unknown but may be due to inequities in healthcare. As we learn more about PCL, it’s possible we’ll find out more about these as well as discover additional risk factors.

Because PCL is so rare, most of what we know about its symptoms comes from various case studies. Many of the symptoms of PCL are associated with organ damage due to the high numbers of abnormal plasma cells in the blood.

The potential symptoms of PCL can include:

The goal of PCL treatment is to lower the numbers of plasma cells in the blood and bone marrow, ideally achieving complete remission. Because PCL is very aggressive, it’s important that treatment begin as soon as possible.

Let’s take a look at how PCL may be treated.


The initial step of treatment is called induction. The goal of induction is to help reduce the number of cancer cells in the body.

The targeted therapy drug bortezomib (Velcade) is often used during induction. It may also be used as a part of combination therapy consisting of the immunomodulator lenalidomide (Revlimid) and the steroid dexamethasone.

Stem cell transplant

A doctor may recommend stem cell transplant as a part of PCL treatment. Typically, good candidates for a stem cell transplant are younger in age and in otherwise good health.

Autologous stem cell transplants are typically used. This is where healthy stem cells are harvested from your own body prior to the transplant, rather than from a donor.

Prior to a stem cell transplant, a high dose of chemotherapy is used to kill the cells in your bone marrow. This destroys both healthy and cancerous cells.

Then, you’ll receive an infusion of the previously harvested stem cells. The goal is for these cells to settle in your body and set up healthy bone marrow.

It’s also possible that a tandem stem cell transplant may be recommended. This involves receiving two autologous stem cell transplants in a row. Receiving a tandem stem cell transplant may help to improve overall survival.

Maintenance therapy

Maintenance therapy occurs after a stem cell transplant. If you’re not eligible for a stem cell transplant, you may receive maintenance therapy after induction therapy.

The goal of maintenance therapy is to help to prevent cancer from coming back or relapsing. It typically involves the use of bortezomib, lenalidomide, or both.

Supportive treatment

Supportive treatments help to address the symptoms or complications associated with PCL and its treatment. Some examples of supportive treatments that may be given as a part of your PCL treatment include:

PCL is an aggressive form of cancer. It may initially respond to treatment, but quick relapses are not uncommon.

Individuals with PCL have an average overall survival of between 4 and 11 months. However, the increased use of autologous stem cell transplants as well as advances in treatments have slightly improved this number.

Some factors that have been found to worsen PCL outlook include:

When we talk about outlook, it’s important to remember that overall survival statistics are based on the observation of many people with PCL. They don’t reflect individual situations.

Receiving a diagnosis of PCL can be very overwhelming. It’s likely that you’ll feel many emotions, which may include anxiety, sadness, or anger. This is completely normal.

It’s important to keep in mind that new treatments are being researched all of the time. These have the potential to improve the outlook for PCL from what’s been previously reported.

Know that there are support resources available to you during this time. Some to check out include:

  • The International Myeloma Foundation. The International Myeloma Foundation offers an InfoLine, information about support groups near you, and a variety of caregiver resources.
  • The Multiple Myeloma Research Foundation. The Multiple Myeloma Research Foundation provides resources like access to support groups, information about financial assistance, and various educational programs.
  • The American Cancer Society. The American Cancer Society has a search tool that can help you find various cancer support resources in your area.

PCL is a rare and aggressive subtype of multiple myeloma. In PCL, abnormal plasma cells grow and divide out of control in the bone marrow and have spread into the bloodstream.

The treatment for PCL can involve various medications with or without a stem cell transplant. Relapses after treatment are common.

While the outlook for PCL is poor, it can be improved with prompt diagnosis and treatment. If you develop concerning signs or symptoms that are consistent with those of PCL, be sure to see a doctor as soon as possible.