Descripción general
Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) is a type of slow-growing lymphoma. The name often is shortened to MALT lymphoma. Lymphoma is cancer that affects the lymphatic system, which is part of the body's immune system.
In MALT lymphoma, the cancer starts in infection-fighting white blood cells in the moist tissue that lines the inside of the nose, mouth, lungs and digestive system. This tissue is called the mucosa. MALT starts in a type of white blood cell called B cells, also called B lymphocytes.
MALT lymphoma happens when the B lymphocytes grow out of control and form a growth of cancer cells in the mucosa. It can happen after long-term infection or irritation in the tissue. For example, an infection with Helicobacter pylori is linked to MALT lymphoma in the stomach. The body sends white blood cells to fight the infection. Over time, this ongoing immune system response can cause changes in some B cells and lead them to grow out of control.
MALT lymphoma can develop in many parts of the body. It happens most often in the stomach. It also can happen in the lungs, thyroid, salivary glands and eyes.
Not all people with MALT lymphoma need treatment at first. If there are no symptoms, healthcare professionals will typically monitor them. Treatment may depend on where the cancer is located. Options may include chemotherapy, immunotherapy, radiation therapy, targeted therapy and bone marrow transplant, also called bone marrow stem cell transplant.
Lymphomas are often grouped into two main types: Hodgkin lymphoma and non-Hodgkin lymphoma. MALT lymphoma is a type of non-Hodgkin lymphoma. More specifically, it is a type of marginal zone lymphoma. MALT lymphoma also is called extranodal marginal zone lymphoma.
Types
Healthcare professionals typically place MALT lymphoma into two categories: stomach-related and not stomach-related. The types of MALT lymphoma include:
Stomach-related MALT lymphoma. This cancer also is called gastric MALT lymphoma. It's the most common type. It starts in the stomach lining. It is typically linked to an H. pylori infection. H. pylori is a type of bacteria that causes irritation and ulcers in the stomach.
Nonstomach-related MALT lymphoma happens in other parts of the body. It can include:
- Immunoproliferative small intestinal disease. This type appears in the small intestine and may begin in the duodenum, which is the first short section of the small intestine, just past the stomach.
- Ocular adnexal MALT lymphoma. This type affects the tissues around the eye, including the tear gland. It may be linked to Chlamydia psittaci infection.
- Salivary gland MALT lymphoma. This type starts in the salivary glands, which is the place where saliva or spit forms. It is usually linked to Sjogren syndrome.
- Pulmonary MALT lymphoma. This type starts in the lung. It is also called bronchial-associated lymphoid tissue (BALT) lymphoma.
- Thyroid MALT lymphoma. This type starts in the thyroid gland. It is typically linked to Hashimoto's disease.
Other, more rare types of MALT lymphoma may affect the breasts, liver and genitourinary (GU) tract. The GU tract involves the urinary system and nearby reproductive organs and includes the bladder, prostate, kidney and uterus.
Síntomas
Signs and symptoms of MALT lymphoma usually depend on what part of the body is involved. In some MALT lymphoma types, there are no noticeable symptoms early on.
MALT lymphoma in the stomach may cause weight loss and general stomach symptoms including:
- A feeling of sour liquid traveling upward in the throat, called reflux.
- Discomfort or pain in the stomach.
- Nausea.
MALT lymphoma can affect other parts of the body:
- In the salivary glands, it may cause swelling in the face and a tumor in the gland.
- In the structures surrounding the eye, called the ocular adnexa, it may cause a tumor, eye redness, constant eye watering, swelling around the eye.
- In the lungs, there may be no symptoms at first. A cough or a shortness of breath may develop. A small nodule or lump may appear on pictures taken of the lungs. Often it is found on a chest X-ray or other imaging test before it causes symptoms.
- In the thyroid, it may cause a growing tumor in the neck that may be painless. The tumor may lead to trouble swallowing, eating or drinking, and hoarseness.
When to see a doctor
Make an appointment with a healthcare professional if you have symptoms that worry you or are not going away.
Causas
It's not always clear what causes MALT lymphoma. This cancer usually does not come from one cause. It is typically linked to ongoing irritation or inflammation caused by infections. Over time, this inflammation can make certain B cells, which are a type of white blood cell, grow in an irregular way and turn into cancer cells.
Factores de riesgo
The factors that increase the risk of MALT lymphoma may include:
- Ongoing infections. Ongoing infections can increase the risk of developing MALT lymphoma. These may include H. pylori, Chlamydia psittaci, Borrelia burgdorferi, Campylobacter jejuni and hepatitis C.
- Autoimmune conditions. Having an autoimmune condition in which the immune system attacks the body by mistake can increase your risk of MALT lymphoma. Such conditions include Hashimoto disease, Sjogren syndrome and others.
- Older age. MALT lymphoma can happen at any age. It is most common in people age 60 and older.
There is no known way to prevent MALT lymphoma.
Complicaciones
MALT lymphoma complications usually depend on the type. Internal bleeding and organ damage may be complications of gastric MALT lymphoma. In rare situations, a slow-growing MALT lymphoma may turn into a more fast-growing type, such as diffuse large B-cell lymphoma. MALT lymphoma also might come back after treatment. This is known as a relapse. Repeated relapses can be common, depending on where the lymphoma started and how advanced it is.