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Splenic marginal zone lymphoma (SMZL) is a type of non-Hodgkin lymphoma (NHL). About 1 percent to 2 percent of all NHL cases are splenic marginal zone lymphoma. This type of cancer is low grade, which means that it grows slowly. People with SMZL often have good outlooks and may live for many years. SMZL doesn’t always need to be treated right away.
Lymphoma is a type of cancer that develops from immune cells called lymphocytes. Lymphocytes are cells that help the body fight infection. SMZL is a type of marginal zone lymphoma (MZL), which develops from lymphocytes called B cells.
MZL develops in tissues of the lymphatic system, in an area called the marginal zone. There are three types of MZL. These subtypes are defined by which tissues they are located in:
People with SMZL have many cancer cells inside the spleen. The spleen is an organ in the upper part of the abdomen, on the left side. The spleen helps kill germs, make new blood cells, and get rid of old or damaged blood cells.
People with hepatitis C virus (HCV) infections are more likely to develop SMZL. About 1 out of 5 people with SMZL are infected with HCV. Autoimmune disorders may also increase risk. However, most people with HCV or autoimmune conditions don’t develop SMZL.
SMZL may not always cause symptoms right away. About 1 out of 4 people do not have symptoms, especially when SMZL is still in its early stages. Eventually, most people with SMZL develop splenomegaly (an enlarged spleen). Splenomegaly can cause:
SMZL can sometimes spread to the bone marrow, a soft tissue inside of certain bones. Cells in the bone marrow make new blood cells. If cancer spreads to the bone marrow, it can crowd out the body’s healthy blood cells, causing cytopenia (low blood cell counts). Some people with SMZL develop anemia (low levels of red blood cells), which may lead to extreme tiredness, shortness of breath, and heart palpitations. SMZL can also cause thrombocytopenia (low levels of platelets), which may lead to bleeding or bruising problems.
Splenic marginal zone lymphoma can also cause B symptoms, which include fever, night sweats, and weight loss. Additionally, 1 out of 5 people with SMZL develop autoimmune disorders such as autoimmune hemolytic anemia, rheumatoid arthritis, or primary biliary cirrhosis.
When diagnosing SMZL, doctors may use blood tests, bone marrow tests, and laboratory tests. Occasionally, surgery is involved in the diagnostic process.
SMZL diagnosis often includes a complete blood count (CBC), in which the levels of each type of blood cell are measured. Other blood tests can help determine how well the kidneys and liver are working. Additionally, doctors may want to measure the blood levels of certain molecules that may serve as signs of cancer, including lactate dehydrogenase (LDH) and beta-2 microglobulin.
Looking inside the bone marrow can help doctors determine whether lymphoma has spread in that area. To analyze the bone marrow, doctors may perform a bone marrow biopsy, in which they remove a small sample of bone tissue, or a bone marrow aspiration, in which they take out a sample of fluid.
Some people may have their spleen surgically removed (splenectomy) before they get an official diagnosis of SMZL. In the case of splenectomy, doctors will typically use pieces of the spleen for further laboratory testing and diagnosis.
Samples from the bone marrow or spleen are sent to a laboratory so that the cells can be further studied. Laboratory tests include histology and immunophenotyping tests such as flow cytometry. These tests help doctors see what the bone marrow or spleen cells look like, determine whether the cells are cancerous, and determine the type of lymphoma. Additionally, tests that look for certain gene changes can help doctors tell SMZL apart from other types of lymphoma.
Doctors may also recommend additional tests to gather more information about lymphoma or about the various health conditions that SMZL can cause. These tests may include:
After diagnosis, doctors determine how far the lymphoma has spread (lymphoma stage). Knowing the lymphoma stage helps doctors plan treatments and estimate prognosis. Doctors stage SMZL using the above tests as well as imaging tests like computed tomography (CT) scans.
Doctors don’t have one standard treatment plan that is always used to treat splenic marginal zone lymphoma. SMZL is rare, which makes it hard to study. However, researchers have found that treatments like surgery, chemotherapy, and targeted therapies can help people have better outcomes. Doctors often recommend different treatment plans based on a person’s symptoms and their overall health.
If SMZL is not causing symptoms, treatment may not be needed. People with asymptomatic SMZL can often live for many years without being treated. Delaying treatment can help people avoid unpleasant side effects. During this time, it is important to have regular follow-up visits with doctors to make sure that the lymphoma is not getting worse.
Doctors sometimes use a splenectomy to treat SMZL. A splenectomy can quickly relieve many SMZL symptoms. However, a splenectomy will not remove all of the lymphoma cells because SMZL usually spreads to the bone marrow. Medications are increasingly becoming more successful at treating SMZL, so doctors don’t use splenectomies to treat SMZL as often as they once did.
SMZL can be treated with several different combinations of chemotherapy drugs. These medications may include:
Rituxan (rituximab) is a targeted therapy that is the most common drug used to treat SMZL. Targeted therapy drugs attack tumor cells while largely leaving the body’s normal cells alone. Many doctors recommend rituximab because it is less toxic and leads to fewer side effects than chemotherapy. In some cases, people with SMZL receive rituximab along with chemotherapy. Other targeted therapies such as Velcade (bortezomib) may also help.
People with SMZL who have a hepatitis C infection often take antiviral drugs to help kill the virus. These drugs may also help treat the lymphoma.
SMZL is indolent (slow growing) and those with this condition often have a good outlook. People live for an average of 10 years after being diagnosed with SMZL.
Sometimes, SMZL can lead to worse outcomes. About 3 out of 10 people with SMZL develop aggressive lymphoma that grows more quickly. People with this faster-growing type live an average of four years after diagnosis. Additionally, SMZL sometimes transforms into diffuse large B-cell lymphoma (DLBCL), a more aggressive type of lymphoma.
Certain prognostic factors increase the chances that a person with SMZL will have a poor outlook:
Talk to your health care team if you would like to know more about your prognosis. Your doctors can help you understand what to expect from splenic marginal zone lymphoma.
A lymphoma diagnosis can be a difficult time, but it may be made easier by connecting with others who share a similar experience. MyLymphomaTeam is the social network for people with lymphoma and their loved ones. On MyLymphomaTeam, more than 8,300 members come together to ask questions, give advice, and share their stories with others who understand life with lymphoma.
Are you living with splenic marginal zone lymphoma? Share your experiences in the comments below, or start a conversation by posting on MyLymphomaTeam.
Todd Gersten, M.D. is a hematologist-oncologist at the Florida Cancer Specialists & Research Institute in Wellington, Florida. Review provided by VeriMed Healthcare Network. Learn more about him here.
Maureen McNulty studied molecular genetics and English at Ohio State University. Learn more about her here.
