Plasmablastic lymphoma (PBL) is an uncommon type of lymphoma. It often develops in people who have immune system problems, such as HIV infections. PBL is fast-growing and may become resistant to treatment. However, treatment can often help people with this lymphoma live longer and have better outcomes.
PBL makes up about 2 percent of HIV-related lymphomas. About 3 out of 4 people with PBL are men. Plasmablastic lymphoma can occur in people of all ages, but it is rare in children.
Lymphomas develop when infection-fighting white blood cells called lymphocytes grow out of control. Lymphoma can begin in different types of lymphocytes. Doctors group lymphomas into subtypes depending on which type of lymphocyte is affected.
Lymphocytes called B cells help the body fight infection by making antibodies — molecules that help the immune system kill germs. When B cells become activated, they transform into a different type of immune cell called plasma cells. During the process of transformation, the cells briefly become a different type of cell called plasmablasts. PBL develops when these plasmablasts become cancerous. PBL is a subtype of diffuse large B-cell lymphoma.
PBL often develops in people who have immunodeficiencies — disorders in which the immune system doesn’t work properly or is disorganized. About half of people with PBL have HIV infections. Others have a suppressed immune system because of organ transplants or autoimmune disorders. Some elderly adults who have working immune systems also develop PBL.
About 2 out of 3 people with PBL also have Epstein-Barr virus (EBV) infections. EBV can cause gene changes that help B cells resist death and grow too quickly.
PBL leads to tumors in various places within the body. The location of PBL cells determines which symptoms a person experiences.
The most common tumor location, accounting for a little less than half of PBL cases, is within the oral cavity (mouth). Oral PBL tumors usually don’t cause many symptoms. They may feel like a lump or a sore. Sometimes, they bleed.
PBL tumors in other parts of the body cause other symptoms, including lumps in the affected location. If tumors occur in the gastrointestinal (digestive) system, they may cause pain, diarrhea, or blood in the stool. PBL masses in the nose may lead to nosebleeds, a runny nose, or inflammation of the sinuses. People with PBL who have had organ transplants are more likely to have PBL in the skin. Skin masses look like a lump or growth underneath the top skin layer.
Most types of lymphoma lead to enlarged lymph nodes, but this symptom is less common in people with HIV-positive PBL. However, about 1 out of 3 people who develop PBL after an organ transplant have swollen lymph nodes.
Some cases of PBL lead to B symptoms, which include drenching night sweats, fever, and unexpected weight loss. These symptoms are more common in people with HIV infections than in those without.
The first step in diagnosing PBL is often a physical exam. Doctors may ask about certain symptoms or look for lymphoma signs. If the doctor suspects lymphoma or another blood cancer, they may recommend tests to look for additional signs and determine the type of cancer.
Doctors may run a few different types of blood tests, such as:
Doctors may recommend a bone marrow biopsy for people who may have lymphoma. In a bone marrow biopsy, a small sample of cells from the spongy tissue inside the bones (the bone marrow) is removed for testing. A bone marrow biopsy can help determine whether lymphoma cells have spread to the bone marrow.
During diagnosis, doctors will also determine the PBL stage (how far lymphoma cells have spread). Staging is performed using the Ann Arbor Staging System. Earlier-stage lymphomas are located in just one specific area of the body. The more advanced the stage, the farther the lymphoma has spread. Most people with PBL have advanced-stage lymphoma by the time they are diagnosed.
There is no one standard treatment plan for PBL. Because PBL is rare, it is hard to study. Researchers are still determining which treatments are likely to work best. PBL is often refractory (resistant to treatment) and frequently relapses (comes back after being treated). However, many treatment options can help people live longer and have a better outcome.
People with PBL are often treated with aggressive chemotherapy plans. Regimens may include:
Some doctors recommend also treating PBL with intrathecal chemotherapy, in which chemotherapy drugs are injected into the fluid surrounding the central nervous system (brain and spinal cord). Intrathecal chemotherapy helps prevent lymphoma cells from entering the central nervous system or helps treat cells that have already spread there.
Autologous stem cell transplantation can sometimes improve outcomes for people with PBL. During this procedure, doctors remove and save a person’s stem cells (cells that make new blood cells). Next, doctors treat lymphoma with very aggressive treatments, which kill both lymphoma cells and healthy blood cells. After these treatments, a person receives an infusion of the saved stem cells, which help regenerate new blood cells.
In a couple of studies, people with PBL have been treated with drugs usually used in multiple myeloma. Multiple myeloma is a cancer of the plasma cells. Because PBL affects similar cells, the same drugs may help fight both types of cancer. For example, doctors have treated PBL with the myeloma-fighting drugs bortezomib (Velcade) and lenalidomide (Revlimid). Doctors may recommend using these drugs along with chemotherapy.
Antiretroviral therapy (ART) drugs help keep HIV under control. HIV-positive people with PBL often take ART as part of their treatment. These medications may help eliminate PBL cells and improve survival rates, though research supporting this is limited at this time.
One study of nearly 300 people with PBL found slightly different survival rates depending on a person’s immune system status:
These survival rates may be steadily improving due to better treatments. Another recent study found that people with PBL lived for an average of 32 months (about 2.7 years) after being diagnosed.
There are many prognostic factors that affect a person’s individual outlook. Doctors estimate prognosis using a system called the International Prognostic Index. This system considers a person’s age, lymphoma stage, levels of LDH, how many parts of the body are affected by lymphoma, and overall wellness. It provides a score that estimates survival rate and likelihood of relapse.
Additional factors that lead to a better outcome include having early-stage (stage 1) lymphoma, an EBV infection, lymphoma cells that contain the CD45 protein, and lymphoma cells that don’t have changes in the c-MYC gene. To learn more about your individual outlook, talk to your health care team. Your doctors can help you understand more about your prognosis based on your personal characteristics.
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