Plasma cell leukemia (PCL) can be difficult to diagnose due to its rarity and symptoms that mimic other diseases. We spoke with cancer experts to learn more about the diagnosis, including its causes, symptoms, and treatment options.
What Is Plasma Cell Leukemia?
“Plasma cell leukemia is a rare and aggressive plasma cell cancer,” said Jeffrey Zonder, MD, hematologist and leader of the Multiple Myeloma and Amyloidosis Multidisciplinary Team (MDT) at the Barbara Ann Karmanos Cancer Institute in Detroit, Michigan.
Plasma cells are a type of white blood cell responsible for producing antibodies to fight infections. In PCL, these plasma cells become cancerous and multiply rapidly in the bone marrow, crowding out healthy blood cells.
“Sometimes, it develops as a late-stage complication of multiple myeloma, and other times, it develops in patients without any history of multiple myeloma,” Dr. Zonder said.
Plasma Cell Leukemia vs Multiple Myeloma
PCL and multiple myeloma are both cancers that affect plasma cells in the bone marrow, but they have some key differences. The main difference is that PCL is much rarer and more aggressive than multiple myeloma.
According to Dr. Zonder, PCL is more likely to:
Have certain high-risk chromosomal changes, detected by bone marrow FISH testing. These changes include a deletion on chromosome 17 (del17p) or a change called a translocation, meaning parts of chromosomes 14 and 16 trade places (t14;16).
Spread to other organs, including the liver, spleen, or other sites outside of the bone marrow
Cause low blood counts
“Because of these aggressive features, the therapies we typically use to treat myeloma are less effective against PCL,” Dr. Zonder said.
According to research published in Haematologica, less than 1% of all people with multiple myeloma will develop PCL.
The exact cause of PCL is unknown, but like other types of leukemia, it’s believed to result from genetic mutations that cause abnormal growth and division of plasma cells. These mutations may be acquired over time or inherited.
Some people are at higher risk of developing PCL. Liudmila Schafer, MD, a board-certified and award-winning medical oncologist at Mercy Clinic Gynecologic Oncology and leader of The Doctor Connect, says the following factors could increase your risk:
Age above 50 years old
Being male (men are slightly more likely to develop PCL than women)
History of multiple myeloma
Certain genetic abnormalities, such as chromosomal changes and gene mutations in the TP53 and MYC genes
“Also, those with a family history of multiple myeloma are at a higher risk,” said Tulio Rodriguez, MD, a hematologic oncologist at the City of Hope Chicago specializing in treating blood cancers. “Exposure to radiation has been linked to the development of plasma cell leukemia as well.”
If you're at higher risk – specifically if you have multiple myeloma or have had it in the past – it's important to discuss any concerning symptoms with your doctor.
Types of Plasma Cell Leukemia
There are two main types of PCL, according to Dr. Schafer:
Primary PCL: When a person develops PCL as their first cancer diagnosis without any prior history of multiple myeloma
Secondary PCL: When a person with a previous diagnosis of multiple myeloma progresses to develop PCL
Both types have similar symptoms, but secondary PCL may have a worse prognosis due to the patient's history of multiple myeloma.
Plasma Cell Leukemia Symptoms
Dr. Schafer and Dr. Rodriguez stated that the symptoms may include any of the following:
When cancerous plasma cells crowd out healthy red blood cells, causing anemia, people with PCL can experience fatigue.
Bleeding and bruising
A reduced number of platelets, which assist in blood clotting, may lead to excessive bruising and bleeding.
Reduced number of healthy white blood cells can lead to increased susceptibility to infections.
The growth of cancer cells in the bone marrow can lead to bone pain, most commonly in the back, hips, and skull.
You may experience weight loss due to cancer's effect on the body.
Weakness or numbness
This can result from cancerous cells pressing on nerves in the spine.
Swollen lymph nodes, liver, or spleen
As the disease advances, it may affect these organs, causing noticeable swelling.
High levels of calcium in the blood may lead to nausea, vomiting, constipation, and confusion.
Similar to multiple myeloma, PCL may also cause other symptoms, such as bone fractures and kidney problems.
Plasma Cell Leukemia Diagnosis
If your doctor suspects you may have PCL, they’ll start by conducting a physical exam and gathering your medical history. They may also order several tests to help confirm the diagnosis, including:
Complete blood count (CBC): This test will check for abnormal red and white blood cell levels and platelets.
Bone marrow biopsy: A small sample of bone marrow is taken and examined for abnormal plasma cells.
Bone imaging: X-rays, CT scans, or MRIs may be used to look for any bone damage caused by cancerous plasma cells.
Other blood tests: These can check for high levels of certain proteins produced by cancerous plasma cells.
What Is the Normal Percentage of Plasma Cells in Bone Marrow?
“The normal percentage of plasma cells in the bone marrow is 2 to 3%,” Dr. Zonder said. An increase in the percentage of plasma cells can indicate the presence of PCL or another condition. This is why a bone marrow biopsy and other tests are necessary for an accurate diagnosis.
“To make the diagnosis, clonal plasma cells need to make up at least 20% of the circulating white blood cells, or the absolute count of clonal plasma cells in the blood is greater than 2 × 109 (2 trillion) per liter,” he added.
Your doctor will develop a personalized treatment plan based on the type of PCL you have. Some of the most common treatments include:
Stem cell transplant
This is a high-dose chemotherapy followed by a rescue with healthy stem cells. The healthy stem cells may come from your own body or a donor. This treatment helps replace the diseased bone marrow with healthy marrow. However, not everyone is a candidate for this procedure due to its risks.
Maintenance therapy helps keep the disease in check for a longer period after initial treatment. It often involves taking a lower dose of chemotherapy or targeted therapy for a set period. This therapy aims to prevent or slow down the disease's return.
This focuses on relieving symptoms and improving your quality of life. It includes treatments like blood transfusions for anemia, antibiotics for infections, and pain medications for bone pain. Additional medications may be given to prevent bone loss or remove excess proteins from the blood.
This newer type of treatment targets specific abnormalities in cancer cells. It works by interfering with the signals that lead to cancer cell growth and division.
These are often used as part of initial PCL treatment but may also be used to relieve symptoms like bone pain.
Plasma Cell Leukemia Survival Rates
“The prognosis of patients with plasma cell leukemia varies, but unfortunately, has a poorer life expectancy compared to multiple myeloma,” said Dr. Rodriguez. Some factors that may impact survival rates include:
Age and overall health: Younger and healthier patients may have a better chance of responding to treatment and surviving longer.
Type of PCL: Secondary PCL typically has a worse prognosis than primary PCL, as it affects people with a history of multiple myeloma.
Response to treatment: Patients who respond well to initial treatment may have a better prognosis.
Presence of other health conditions: Patients with other significant health conditions may have a harder time tolerating treatment, leading to a worse prognosis.
2021 research published in the Blood Cancer Journal states that treatment advancements haven't improved as much in recent years compared to other types of blood cancers, like multiple myeloma, possibly because PCL is much rarer.
However, continued research and clinical trials offer hope for improved treatments and survival rates in the future. “Regular medical check-ups and awareness of these factors can be helpful in the early detection and management of plasma cell leukemia,” Dr. Rodriguez said.
Research has yet to fully explain what causes PCL, but genetic mutations and exposure to certain chemicals may play a role in its development. People with a history of multiple myeloma should be aware of the potential for secondary PCL.