What is MALT Lymphoma?

MALT Lymphoma - An Extranodal Marginal Zone-B Lymphoma

What is MALT lymphoma?. Istockphoto.com/Stock Photo©Imtmphoto

What is MALT lymphoma, what are the causes, and how is it treated?

MALT Lymphoma - Definition

MALT lymphoma is an uncommon form of Non-Hodgkin Lymphoma (NHL). MALT stands for 'mucosa-associated lymphoid tissue'. Unlike most other lymphomas that occur in lymph nodes (or lymph glands), this lymphoma arises from lymph tissue present in the lining of some other organs of the body.

MALT lymphoma is also medically known as an extranodal marginal zone B-cell lymphoma.

That simply means that it is a type of B-cell non-Hodgkin lymphoma that arises not from nodes but other organs.

Who is Affected by MALT Lymphoma?

MALT lymphomas account for only about 5% of all non-Hodgkin lymphomas. They are more common in older adults, but may occur in individuals in their twenties and thirties. It is slightly more common in women than in men.

Which Organs of the Body are Affected?

The most commonly affected organ in MALT lymphoma is the stomach, which accounts for nearly 2 out of every 3 cases. This is often referred to as 'gastric MALT lymphoma.'  But other organs are also affected by MALT lymphoma. The lung, thyroid, salivary glands and the eye may also be affected by this lymphoma.

What Causes MALT lymphoma?

MALT lymphomas of the stomach are associated with a bacterial infection. Helicobacter pylori is a type of bacteria that commonly infects the stomach and causes ulcers and gastritis.

In some individuals it can also cause MALT lymphomas. It isn't unusual to have a "germ" responsible for gastric MALT lymphoma as other bacteria, viruses, and parasites are risk factors for other lymphomas. This make sense knowing that it is the lymph system that is responsible for identifying and fighting off foreign organisms in our body.

Worldwide, roughly 20% of cancers are related to infections. Risk factors for MALT lymphomas also include infection with Chlamydophilia psittaci, and autoimmune diseases.

How does MALT lymphoma behave?

MALT lymphomas are low grade lymphomas. They grow slowly and remain confined to one organ for a relatively long time. When talking about lymphomas which are slow growing, oncologists often use the term 'indolent.' The majority of patients with MALT lymphoma are diagnosed early, before the disease has spread to other organs and lymph nodes.

What are the Symptoms of MALT Lymphoma?

The symptoms of MALT lymphoma depend on the organ affected. When MALT lymphoma affects the stomach, you may feel indigestion, weight loss, and black stools because of bleeding into the stomach. Some people may feel a vague pain in the abdomen.

Tests for MALT Lymphoma:

To diagnose a MALT lymphoma, the doctor will need to take a biopsy from the tumor. For MALT lymphomas of the stomach this usually involves an endoscopy.

Doctors will also test for the presence of the H. pylori bacteria in the stomach. Other tests that will need to be performed include blood tests, scans of the abdomen and chest, and also a bone marrow test.

Staging of MALT Lymphomas:

The staging of lymphomas involves 3 separate ratings.  They are first diagnosed between stage I and IV based on how extensive they are.  Then the letter A or B is given based on symptoms.  There are also 2 more letters, E and S, in which E stands for 'extraproliferative' or outside of the lymphatic system, and S represents presence of the cancer in the spleen.  MALT lymphomas do not arise in lymph nodes, nor do they commonly spread to other organs. Most MALT lymphomas are diagnosed in Stage IE, meaning they are present in only one organ and that it is outside of the lymphatic system.  Only about 20% of MALT lymphomas are in advanced stage at diagnosis.

Treatment of MALT Lymphomas:

Treatment of MALT lymphomas depend on the organ involved and the stage of diagnosis. In most patients local treatments like radiation or surgery may be adequate to deal with the disease, but systemic therapy such as chemotherapy is often used for higher stage cancers, and may be used to reduce the risk of recurrence with early stage cancers.

Treatment for MALT lymphomas of the stomach consists of eradicating the infection with H pylori.  This alone is sufficient to eliminate the cancer in a large percentage of people.

Sources:

Nakamura, S., and T. Matsumoto. Treatment Strategy for Gastric Mucosa-Associated Lymphoid Tissue Lymphoma. Gastrenterology Clinics of North America. 2015. 44(3):649-60.

Raderer, M., Kiesewetter, B., Ferreri, A. et al. Clinicopathologic characteristics and treatment of marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma), CA: A Cancer Journal for Clinicians. 2015 Nov 24. (Epub ahead of print).

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