What Is Mucosa-Associated Lymphoid Tissue?

The term mucosa-associated lymphoid tissue (MALT) is used to describe lymphoid tissue which is found along the mucosa. Lymphoid tissue is part of the lymphatic system which drains fluid, filters out harmful substances and helps protect the body from infection. Mucosa is the tissue that lines spaces and passages such as the stomach and intestines. A type of cancer known as MALT lymphoma, or MALToma, can develop from mucosa-associated lymphatic tissue. As the tumor usually grows slowly, the outlook is often positive.

MALT is associated with those body surfaces, such as the intestinal lining, that may come into contact with potentially harmful substances. Apart from the gut, there are numerous sites inside the body where mucosa-associated lymphoid tissue may be found, including the skin, eye, lungs, nose and mouth. Organs such as the thyroid and salivary glands also contain MALT. Structurally, MALT may be made up of what are called lymph nodes, which are small lumps of specialized tissue which is able to fight infection. Sometimes the tissue consists of a collection of individual lymphoid cells.

When a lymphoma arises in mucosa-associated lymphoid tissue, it most often develops in the stomach of an older person. There is an association with what are called autoimmune diseases. For example, people with thyroid disease may develop a MALToma of the thyroid gland, while a MALT lymphoma in the salivary glands can be associated with the disease known as Sjogren's syndrome. In the digestive system, a cancer of this tissue may cause symptoms such as abdominal pain, bleeding or a blocked gut. MALTomas of the stomach are often associated with a long-term, or chronic, infection caused by the bacterium H.pylori.

A lymphoma of mucosa-associated lymphoid tissue might be treated with surgery, radiotherapy or chemotherapy. The exact treatment will depend on the tumor's location and the extent to which it has spread. A stomach MALToma may be managed with antibiotics, which can often shrink the tumor.

MALTomas are typically known as low-grade tumors, which progress very slowly, and patients usually survive for a long time. There is a possibility that a MALToma could recur after treatment, so patients are usually followed up with regular examinations. For a MALToma in the stomach, a series of endoscopies might be carried out, where an instrument with a camera is passed down the esophagus to spot any signs of tumor recurrence.