Marginal Zone Lymphoma (MZL)
Lymphoma is the most common blood cancer. The two main forms of lymphoma are Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL). Lymphoma occurs when cells of the immune system called lymphocytes, a type of white blood cell, grow and multiply uncontrollably. Cancerous lymphocytes can travel to many parts of the body, including the lymph nodes, spleen, bone marrow, blood, or other organs, and form a mass called a tumor. The body has two main types of lymphocytes that can develop into lymphomas: B-lymphocytes (B-cells) and T-lymphocytes (T-cells).
Marginal zone lymphomas are a group of indolent (slow-growing) NHL B-cell lymphomas, which account for approximately 12 percent of all B-cell lymphomas. The median age for diagnosis is 65 years old
There are three types of marginal zone lymphoma:
Extranodal marginal zone lymphoma or mucosa-associated lymphoid tissue (MALT) is the most common form of marginal zone lymphoma. It occurs outside the lymph nodes, in places such as the stomach, small intestine, salivary gland, thyroid, eyes, and lungs. MALT lymphoma is divided into two categories: gastric, which develops in the stomach, and non-gastric, which develops outside of the stomach. This form of lymphoma makes up about nine percent of all B-cell lymphomas.
In many cases of MALT lymphoma, there is a previous medical history of inflammation or autoimmune disorders. For example, Helicobacter pylori (H. pylori), a microbial pathogen linked to chronic gastritis, has been associated with a significant portion of patients with gastric MALT lymphoma.
Nodal marginal zone lymphoma (sometimes called monocytoid B-cell lymphoma) occurs within the lymph nodes and accounts for about two percent of all B-cell lymphomas.
Splenic marginal zone lymphoma occurs most often in the spleen and blood. It has been associated with Hepatitis C. This form of lymphoma makes up about one percent of all B-cell lymphomas.