Lymphoma is a type of cancer that begins in lymphocytes, which are white blood cells that play a role in the body’s immune system. These cells are part of the lymphatic system, a network of tissues and organs that help rid the body of toxins, waste, and other unwanted materials. Marginal zone lymphoma (MZL) represents a specific category within non-Hodgkin lymphoma, characterized by its typically slow-growing nature. This article aims to clarify what marginal zone lymphoma is, its different forms, how it is identified, and the approaches used for its management.
What is Marginal Zone Lymphoma?
Marginal zone lymphoma is a type of non-Hodgkin lymphoma that develops from B-cells, a specific kind of lymphocyte. These B-cells originate in the marginal zones, which are regions found at the edges of normal lymphoid tissues. MZL is considered an indolent, or slow-growing, lymphoma, meaning it progresses at a more gradual pace compared to aggressive forms of lymphoma.
The development of MZL often involves a mutation in these B-cells, leading to their uncontrolled multiplication. This overproduction of abnormal B-cells can accumulate in various parts of the body, forming masses or affecting organ function. Its slow progression often means that individuals may live with the condition for years before needing active treatment.
Types of Marginal Zone Lymphoma
Marginal zone lymphoma is categorized into three primary subtypes, each distinguished by where it arises in the body.
Extranodal Marginal Zone Lymphoma (MALT Lymphoma)
The most common form is extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue, often referred to as MALT lymphoma. This type develops outside the lymph nodes, frequently in organs like the stomach, but can also appear in the lungs, skin, thyroid, or salivary glands. Gastric MALT lymphoma has been linked to chronic inflammation often caused by Helicobacter pylori (H. pylori) bacterial infection.
Nodal Marginal Zone Lymphoma
Another subtype is nodal marginal zone lymphoma, which primarily affects the lymph nodes. While it starts within the lymph nodes, it does not frequently spread beyond them and exhibits slow growth.
Splenic Marginal Zone Lymphoma
The third subtype, splenic marginal zone lymphoma, involves the spleen, blood, and bone marrow. This particular subtype has been associated with hepatitis C virus infection.
Recognizing Symptoms and Diagnosis
The signs and symptoms of marginal zone lymphoma can differ considerably depending on the specific subtype and the body area affected. For instance, extranodal MALT lymphoma in the stomach may cause symptoms such as indigestion, nausea, vomiting, or abdominal pain. If MALT lymphoma affects the skin, it might present as a rash, while involvement around the eye could lead to discharge or discomfort. Individuals with nodal marginal zone lymphoma might notice painless swollen lymph nodes, commonly in the neck, armpit, or groin. Splenic marginal zone lymphoma can lead to an enlarged spleen, causing a feeling of fullness after eating only small amounts of food, or generalized fatigue.
Beyond these localized signs, some individuals with MZL may experience more generalized symptoms, often referred to as “B symptoms.” These can include unexplained weight loss, night sweats, and fever without an apparent infection.
Diagnosing MZL typically begins with a physical examination, where a doctor checks for swollen lymph nodes or an enlarged spleen. Blood tests are also performed to assess general health, check blood cell counts, and screen for infections such as hepatitis C or H. pylori. Imaging scans, including CT, PET, and MRI, help determine the location and extent of the lymphoma. A biopsy, which involves taking a tissue sample from an affected lymph node, bone marrow, or other involved site, is performed to confirm the diagnosis. This sample is then examined by a pathologist to identify the specific type of lymphoma and its characteristics.
Treatment Options
Treatment decisions for marginal zone lymphoma are highly individualized, taking into account the specific subtype, the stage of the disease, the presence and severity of symptoms, and the patient’s overall health. For individuals with slow-growing MZL that is not causing significant symptoms, a “watchful waiting” approach, also known as active surveillance, may be adopted. This involves regular monitoring of the condition without immediate intervention.
For MALT lymphomas linked to H. pylori infection, antibiotic therapy is often the first line of treatment and can lead to the lymphoma regressing or even disappearing in a significant number of cases. Similarly, if splenic MZL is associated with hepatitis C, antiviral treatment for the infection may resolve the lymphoma.
Localized MZL may be treated with radiation therapy, which uses high-energy rays to target and destroy cancer cells in specific areas. Immunotherapy, frequently involving monoclonal antibodies like rituximab, is a common treatment, often used alone or in combination with chemotherapy. Chemotherapy, which uses drugs to kill cancer cells, may be used for more advanced disease or when other treatments are not effective, often as part of a chemo-immunotherapy regimen. In rare instances, surgery, such as removal of the spleen for splenic MZL, or resection of localized extranodal disease, may be an option.
Prognosis and Ongoing Care
Marginal zone lymphoma generally has a favorable outlook compared to more aggressive lymphomas, largely due to its indolent nature. Many individuals achieve remission with treatment, meaning the signs and symptoms of the cancer are reduced or disappear. However, MZL has a tendency to recur, with relapse being a possibility even after successful treatment.
Because of the potential for recurrence, long-term follow-up care is an important aspect of managing MZL. This ongoing monitoring typically involves regular check-ups, blood tests, and sometimes imaging scans or biopsies to detect any signs of the lymphoma returning or progressing. Survivorship care focuses on managing any long-term side effects from treatment and maintaining overall well-being.