MALT lymphoma is a slow-growing type of non-Hodgkin lymphoma, a cancer that originates in the lymphatic system. The disease develops from the abnormal and uncontrolled growth of a white blood cell called a B-lymphocyte. Its full name, extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue, describes where it develops—outside of the lymph nodes in tissue that lines various organs throughout the body.
Understanding MALT Lymphoma
Mucosa-associated lymphoid tissue, or MALT, is a component of the body’s immune system. This specialized tissue is found in the lining, or mucosa, of many organs, including the stomach, lungs, intestines, eyes, and salivary glands. Its primary function is to protect these surfaces from infection. The tissue contains collections of immune cells, primarily B-lymphocytes, ready to respond.
Lymphoma develops in this tissue when B-lymphocytes multiply without restraint. These abnormal cells accumulate in the MALT, forming tumors. This means the disease progresses slowly, and in some cases, may not require immediate treatment.
MALT lymphoma can arise in almost any part of the body containing this specific tissue, but it is most frequently found in the stomach, a condition known as gastric MALT lymphoma. Non-gastric MALT lymphoma refers to cases that originate in other areas, such as the thyroid gland, skin, or lungs. MALT lymphoma is rare, accounting for about 8% of all non-Hodgkin lymphomas.
Common Symptoms by Location
The signs of MALT lymphoma are related to the organ where the cancer is growing. Many individuals may not experience any symptoms, with the lymphoma being discovered during medical tests for other issues.
For gastric MALT lymphoma, which develops in the stomach, symptoms can include:
- Persistent indigestion
- Pain in the abdomen
- Nausea or vomiting
- A loss of appetite
- Unintentional weight loss
In non-gastric cases, symptoms vary widely. When MALT lymphoma affects the eyes, it can cause redness, swelling, blurry vision, or a noticeable lump. If the cancer is in the lungs, a person might experience a chronic cough, shortness of breath, or chest pain. For lymphomas in the salivary glands, a lump may be felt in the jaw or mouth.
General symptoms often associated with other types of lymphoma, known as B symptoms, are less common in MALT lymphoma unless the disease is more advanced. These systemic symptoms include drenching night sweats, unexplained fevers, and significant weight loss. Their presence helps doctors plan the appropriate course of action.
Causes and Diagnostic Process
MALT lymphoma is often linked to long-term inflammation from chronic infections or autoimmune conditions. There is a strong association between gastric MALT lymphoma and a bacterial infection in the stomach called Helicobacter pylori (H. pylori). This bacterium causes persistent inflammation of the stomach lining, and while most people with H. pylori do not develop cancer, approximately 90% of those with gastric MALT lymphoma have the infection.
Certain autoimmune diseases are also connected to the development of MALT lymphoma in specific locations. For instance, Sjögren’s syndrome is linked to lymphomas in the salivary glands and near the eyes. Hashimoto’s thyroiditis is associated with MALT lymphoma of the thyroid gland.
Confirming a diagnosis of MALT lymphoma requires a biopsy, where a small sample of the affected tissue is removed and examined by a pathologist. For suspected gastric cases, an upper endoscopy is performed to collect biopsy samples from the stomach lining. Imaging tests such as CT scans or PET scans may be used to see the location and extent of the lymphoma, while blood tests check for general health markers.
Treatment Approaches and General Outlook
Treatment for MALT lymphoma is highly individualized, based on the cancer’s location, stage, and the person’s overall health. For gastric MALT lymphoma caused by H. pylori, the primary treatment is a course of antibiotics to eliminate the infection. Eradicating the bacteria can lead to complete remission of the lymphoma in many cases.
For localized MALT lymphoma in other parts of the body, radiation therapy can be an effective treatment. In some situations where the lymphoma is slow-growing and not causing any symptoms, a strategy of “watchful waiting” or active surveillance may be recommended. This involves regular check-ups to monitor the condition without immediate treatment.
If the lymphoma is more widespread or does not respond to initial treatments, other options are available. These include chemotherapy or targeted therapies like rituximab, used alone or in combination. The general outlook for individuals with MALT lymphoma is favorable, especially for localized disease or gastric cases that respond to antibiotic treatment. However, recurrence is possible, so long-term follow-up care is necessary.