Primary effusion lymphoma (PEL) is a type of non-Hodgkin lymphoma (NHL). Unlike many other types of lymphoma, PEL does not usually lead to tumors. Instead, it causes fluid-containing cancer cells to fill up different cavities (spaces in the body).

PEL is rare, making up less than 1 percent of all lymphomas. It most often affects men who have AIDS and represents 4 percent of all NHLs related to HIV. PEL has a unique clinical presentation in that it arises in body cavities, such as the space between the lungs and chest wall, around the heart, and the lining of the abdomen.

What Is Primary Effusion Lymphoma?

Lymphoma develops from lymphocytes, a type of white blood cell that fights infections. There are three main types of lymphocytes. About 90 percent of lymphomas, including PEL, develop from B lymphocytes. A type of large-cell lymphoma, PEL may be treated in the same way as other large-cell lymphomas, such as diffuse large B-cell lymphoma.

Lymphomas are often categorized as indolent (slow-growing) or aggressive (fast-growing). PEL is a very aggressive form of lymphoma. People with PEL need to start treatment right away.

Causes of Primary Effusion Lymphoma

PEL is strongly linked to viral infections. These infections are more likely to develop in people with immune system problems. Most cases of PEL occur in those who have AIDS, a disease that leads to very low levels of immune cells. In some cases, PEL develops in people who have other conditions that weaken the immune system. Organ transplants, cirrhosis (scarring of the liver), autoimmune diseases, or cancer can all decrease a person’s immunity. PEL can also develop in elderly people who have working — but less active — immune systems.

When the immune system doesn’t work properly, it leaves a person more vulnerable to infection. People with PEL are often infected with human herpesvirus-8 (HHV-8), also called Kaposi’s sarcoma-associated herpesvirus. Additionally, 80 percent of people with PEL have Epstein-Barr virus infections.

Researchers believe that these viruses make cells become cancerous and encourage them to grow out of control. They also help cancer cells avoid being killed by the immune system.

Signs and Symptoms of PEL

In other types of lymphoma, cancerous lymphocytes build up within the lymphatic system. The lymphatic system is a collection of tissues and organs that help fight infection and remove extra fluid. Lymphoma most often causes cells to accumulate in lymph organs or in lymph nodes (small glands found throughout the body), forming tumors.

PEL acts differently. Many people with this condition do not have any tumors or enlarged lymph nodes. Instead, they have effusion (fluid buildup) within body cavities. PEL can cause effusions in multiple locations in the body, leading to different symptoms:

• Pleural effusion (fluid buildup around the lungs), leading to shortness of breath
• Pericardial effusion (fluid buildup in the space surrounding the heart), leading to shortness of breath, dizziness, and low blood pressure
• Peritoneal effusion (fluid buildup in the abdomen), which can cause feelings of bloating in the belly and swelling in the feet or legs

Some people with PEL also experience B symptoms. This set of symptoms occurs in many types of lymphoma and includes fever, night sweats, and weight loss.

In rare cases, PEL may spread from the body cavities to other parts of the body. Tumor cells may be found in the digestive system, skin, lung, or lymph nodes. If PEL cells spread, they may form tumor masses in these locations.

Primary Effusion Lymphoma Diagnosis

Doctors use a variety of tests to diagnose lymphoma. Often, diagnosis begins with a physical exam, in which a doctor looks for lymphoma signs and asks about symptoms. Doctors may then recommend tests like biopsies, immunohistochemistry, immunophenotyping, tests to look for viral infections, and imaging studies.

Effusion Tests

Diagnosing PEL involves studying the fluid that fills the body cavities. Doctors may take a small sample of the fluid to determine if cancer cells are present. Additionally, doctors may perform a biopsy (remove a small sample of tissue) to study the membranes that line the body cavity.

Immunohistochemistry and Immunophenotyping

During immunohistochemistry (IHC) tests, doctors study cells under a microscope. IHC helps doctors analyze whether cells are cancerous. These tests can also help show whether cells are PEL or another type of lymphoma.

Immunophenotyping can also tell PEL apart from other lymphomas. Immunophenotyping tests “read” the proteins found on the outer surface of cells. Different types of cancer cells tend to contain different surface proteins.

Viral Tests

PEL cells always contain the HHV-8 virus, so doctors will look for signs of viral infection in order to confirm that a person has this lymphoma. HHV-8 makes a protein called latency-associated nuclear antigen 1 (LANA-1). Doctors perform tests to look for this protein inside of lymphoma cells. If LANA-1 is present, that means that cells are infected with HHV-8 and are likely PEL cells.

Imaging Tests

If PEL is diagnosed, doctors will also study how advanced it is. Doctors use imaging tests such as positron emission tomography or CT scans. These tests show whether PEL has spread to other parts of the body.

Treatments for PEL

PEL is rare, which makes it difficult to study. Doctors don’t have a standard treatment plan for this lymphoma. However, most doctors recommend treatment with chemotherapy and antiviral drugs. In rare cases, doctors have also used stem cell transplants to treat PEL.

Chemotherapy

PEL cells are often resistant to chemotherapy. However, some chemotherapy drugs can kill cancer cells and help a person have a complete response (have all signs of cancer disappear).

Doctors may recommend a regimen of drugs called CHOP. This regimen consists of a combination of chemotherapy drugs:

• Cyclophosphamide (sold as Cytoxan)
• Doxorubicin (also known as hydroxydaunorubicin and sold as Adriamycin)
• Vincristine sulfate (formerly sold as Oncovin)
• Prednisone

Adding high-dose methotrexate to the usual CHOP regimen may increase the chances that someone will have a complete response. Additionally, doctors may recommend a related regimen, EPOCH, which contains all of the drugs found in CHOP plus the drug etoposide.

Another chemotherapy regimen that may help treat PEL is ACVBP, which includes doxorubicin, cyclophosphamide, vincristine, bleomycin (sold as Blenoxane), and prednisone.

Antiretroviral Drugs

People with HIV infections often receive antiretroviral therapies (ARTs) while undergoing treatment for primary effusion lymphoma. ART drugs help keep HIV under control. They prevent the immune system from becoming damaged and help the body better fight off lymphoma.

Stem Cell Transplant

A couple of small studies have found that autologous stem cell transplants may help people with PEL. During an autologous stem cell transplant, doctors remove and save some of a person’s blood stem cells (cells that create new blood cells). Next, the person undergoes aggressive treatments that kill both cancerous and healthy blood cells. Doctors then deliver the saved stem cells back into the body, where they can replace the blood cells that were lost.

Stem cell transplants have not yet been well-studied for people with PEL. Additionally, stem cell transplantation can cause serious side effects. This procedure is usually only an option for people who are younger, have a stronger immune system, and are in otherwise good health.

New Treatments for PEL

Doctors are increasingly treating lymphoma with new therapies. Targeted therapy drugs can recognize and attack cancer cells while mostly leaving normal cells alone. Additionally, immunomodulatory drugs boost the immune system to help it better fight cancer.

Researchers are studying whether any targeted therapies or immunomodulatory drugs may be able to help treat PEL. People with this lymphoma may be able to access new drugs or new treatment plans by participating in a clinical trial.

Primary Effusion Lymphoma Outlook

PEL is difficult to treat, and people with this condition usually have a poor prognosis (outlook). About half of people with PEL live for 10 months or more after being diagnosed.

People tend to have better outcomes if they are in better overall health, were taking ARTs before they were diagnosed with PEL, or have PEL cells in only one body cavity. People who are HIV-negative often have a better outlook than those who are HIV-positive.

Talk With Others Who Understand

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