Mucosa-associated lymphoid tissue (MALT) lymphoma is a blood cancer that can occur in any part of the body, but it often develops in the stomach. It is a type of non-Hodgkin lymphoma (NHL). MALT lymphoma is also called extranodal marginal zone B-cell lymphoma.

MALT lymphoma is more common in older adults. People are diagnosed with MALT lymphoma at an average age of 60. Treatments usually work well and can often cure this lymphoma.

What Is MALT Lymphoma?

Lymphoma affects lymphocytes, a type of white blood cell that forms within bone marrow tissue. As lymphocytes develop, they become a part of the body’s lymphatic system — the network of tubes, organs, and lymph nodes that fights infection and filters out waste. Lymphoma develops from B cells, a type of lymphocyte, when they become abnormal and stop responding to the controls of the body. Cancerous lymphocytes may be found in different tissues and organs of the lymphatic system, and sometimes in the bone marrow and blood.

There are many different types of lymphoma. About 5 percent to 10 percent of lymphomas are marginal zone lymphomas, named because they occur in areas of lymphoid tissue called the marginal zones. There are three types of marginal zone lymphoma, which are classified by their location in the body:

• MALT lymphoma occurs in places that are extranodal (outside of the lymph nodes).
• Nodal marginal zone lymphoma develops in the lymph nodes.
• Splenic marginal zone lymphoma occurs in the spleen, although lymphoma cells may also be found in the blood and bone marrow.

MALT lymphoma is the most common type of marginal zone lymphoma. It affects mucosa-associated lymphoid tissue. Mucosa is tissue that lines certain body cavities or organs, such as the:

• Mouth
• Gastrointestinal (digestive) system
• Nose
• Lungs

Lymphoid tissue includes any area in the body where lymphocytes grow, develop, or occupy.

Types of MALT Lymphoma

About 1 out of 3 cases of MALT lymphoma develops in the gastric mucosa (the inner lining of the stomach). These cases are known as gastric MALT lymphoma. MALT lymphoma can occur in many other locations, but it is most often found in the:

• Lungs
• Salivary (spit) glands
• Thyroid
• Intestines
• Skin
• Eyes

This is called nongastric MALT lymphoma.

What Causes MALT Lymphoma?

Most people who have gastric MALT lymphoma are infected with Helicobacter pylori, a type of bacteria that often lives in the stomach. H. pylori infections are very common, and most people who have this bacteria do not develop lymphoma.

Nongastric MALT lymphoma is linked to other risk factors. Some people with this cancer have other types of infections. Others have autoimmune diseases like Hashimoto’s thyroiditis or Sjögren’s syndrome.

MALT Lymphoma Symptoms

MALT lymphoma symptoms differ significantly depending on the cancer's location in the body:

• Stomach — Upset stomach, abdominal pain, nausea, vomiting, or weight loss
• Lungs — Cough, shortness of breath, pain in the chest, coughing up blood
• Salivary glands — Lump in the mouth or jaw, or in front of the ear
• Thyroid — Bump at the base of the neck, shortness of breath, trouble swallowing, hoarse voice, tiredness, weight gain
• Gastrointestinal system — Diarrhea, bloating, abdominal pain, weight loss, tiredness
• Skin — Pink or purplish patches on the chest, back, or arms
• Eye — Dark lumps inside the eyelid or near the corner of the eye, eye redness, blurry vision, drooping eyelid

MALT lymphoma very often does not cause any symptoms at all. It is usually only discovered after a person undergoes tests for something else. However, if you notice any symptoms that could indicate MALT lymphoma, talk to your doctor.

Diagnosing MALT Lymphoma

MALT lymphoma may be diagnosed with a mixture of:

• Blood tests
• Imaging
• Bone marrow tests
• Biopsies (removal of a small piece of tissue)

These tests determine whether or not you have lymphoma and help the doctor estimate outlook and make treatment recommendations.

Biopsies for MALT Lymphoma

A tissue biopsy is an important part of diagnosing lymphoma. It helps a doctor determine whether there are cancer cells in a particular area. For people with MALT lymphoma, the doctor will select the biopsy location based on where they believe the cancer to be located.

People with gastric MALT lymphoma will need to have a biopsy taken from their stomach tissue. This biopsy is usually accomplished using an endoscopy — a test in which a camera attached to a long, thin tube is passed down your mouth and into your stomach.

An endoscopy may also be used to look at MALT lymphoma in other locations. The tube may be passed through your rectum to look at your intestines. If you have MALT lymphoma in your lungs, the tube will be passed down your windpipe.

Other Diagnostic Tests

A variety of other tests may also be used to diagnose blood cancer or learn more about the lymphoma cells. Blood tests are often a part of diagnosis and may include:

• A complete blood count to measure levels of each type of blood cell
• Tests for bacterial or viral infections
• Tests that show how well your kidneys and liver are working

Some people with MALT lymphoma may need bone marrow tests, which may include a bone marrow biopsy (removal of cells from the bone) and a bone marrow aspiration (removal of liquid). Bone marrow tests can show whether there are cancer cells in the bone marrow.

Other tests can help doctors determine a treatment plan. Biopsy samples may undergo immunohistochemistry tests to look for specific proteins. They may also undergo cytogenetic tests to look for certain gene changes. Knowing which abnormal genes or proteins the lymphoma cells have provides clues as to which treatments may or may not work. Additionally, people with gastric MALT lymphoma may need breath or stool tests for H. pylori bacteria.

MALT Lymphoma Stages

If you are diagnosed with MALT lymphoma, your doctor will also determine your lymphoma’s stage. The stage describes how advanced the cancer is, and how far the lymphoma has spread throughout the body.

Information from the above tests can be used to help estimate stages. Imaging tests are also usually recommended. These include computed tomography (CT), MRI, and ultrasound scans. In some cases, a positron emission tomography (PET) scan is also used to help plan treatment or determine which tissue to biopsy.

Different systems are available for determining the stage of a person’s lymphoma. Traditionally, doctors have used the Lugano system, although some now use newer systems like the Paris staging system. These systems assign a stage, 1-4, based on which tissues are affected and whether lymphoma cells have spread to nearby tissues or to more distant locations.

Treatments for MALT Lymphoma

Multiple treatments may be used to manage MALT lymphoma. The type of treatment your doctor recommends is based on your overall health, your symptoms, and the stage of your lymphoma.

Gastric MALT Lymphoma Treatments

Gastric MALT lymphoma is usually caused by H. pylori infection, so treatment begins with curing the infection. Antibiotic therapy is usually recommended — along with proton pump inhibitors, which can help heal damage to the stomach. This treatment cures lymphoma in about 90 percent of cases.

If gastric MALT lymphoma is refractory (doesn’t go away after being treated) or relapses (comes back after being treated), other treatments may be used. Rituxan (rituximab) and Imbruvica (ibrutinib) are targeted therapy drugs that can attack specific proteins found in lymphoma cells. The U.S. Food and Drug Administration also recently approved another targeted therapy, Ukoniq (umbralisib), to treat marginal zone lymphomas like MALT lymphoma. Surgery and radiation therapy may also be used to treat MALT lymphoma that doesn’t respond to drug therapy.

Nongastric MALT Lymphoma Treatments

Treatments for this type of lymphoma depend on symptoms. If a person has early stage MALT lymphoma, they may not need treatment right away. The strategy in these instances, called “watch and wait,” consists of frequent follow-up visits and tests to monitor the lymphoma and determine whether it is becoming more advanced.

People who have worsening symptoms of lymphoma generally need to begin treatment. Treatment may sometimes include surgery to remove the lymphoma tissue. If the lymphoma is located in just one area of the body, radiotherapy (radiation treatments) is also often used.

More severe cases of lymphoma are treated with chemotherapy drugs. One common treatment plan is a drug combination called CHOP, which comprises:

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

Chemotherapy is often given with targeted therapy drugs like rituximab.

Some cases of nongastric MALT lymphoma are also caused by infection. For example, infection is occasionally linked to MALT lymphoma located near the eye. Antibiotics such as Vibramycin (doxycycline) may be a part of the treatment plan for these lymphomas.

Outlook for MALT Lymphoma

Treatments for MALT lymphoma are usually effective. Nearly 9 out of 10 people with MALT lymphoma will live for at least five years after being diagnosed. Each individual person’s prognosis (outlook) may be different. You may be more likely to have a worse outlook if:

• You are 70 or older
• You have stage 3 or 4 lymphoma
• You have high levels of lactate dehydrogenase in your blood

In some cases, MALT lymphoma can transform into a faster-growing lymphoma, such as diffuse large B-cell lymphoma. In this case, it will require more complex and stronger treatments.

Talk With Others Who Understand

MyLymphomaTeam is the social network for people with lymphoma and their loved ones. On MyLymphomaTeam, members come together to ask questions, give advice, and share their stories with others who understand life with lymphoma.

Are you living with MALT Lymphoma? Share your experiences in the comments below, or start a conversation by posting on MyLymphomaTeam.