Cancer

08 October 2008

Lymphoma

Lymphomas are cancers that develop in the lymph system, which is part of the body's immune system. Therefore people with HIV/Aids are susceptible to lymphoma.

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Description
  • Lymphomas are cancers that develop in the lymphatic system, which is part of the body's immune system.
  • Because there is lymphoid tissue throughout the body, lymphomas can start in any part.
  • Lymphomas are divided into two general types: Hodgkin's lymphomas and non-Hodgkin's lymphomas.
  • Lymphoma often causes fever and drenching night sweats; other symptoms depend on which area of the body is affected.
  • Lymphoma may be treated with chemotherapy; lymphoma involving the brain may also be treated with radiation therapy.

What is lymphoma and what causes it?
Lymphomas are cancers that develop in the lymphatic system, which is part of the body's immune system.

The lymphatic system is made up of thin tubes that branch, like blood vessels, into all parts of the body. Lymph vessels carry lymph, a watery fluid that contains white blood cells called lymphocytes. Along the network of vessels are groups of small, bean-shaped organs called lymph nodes, which make and store infection-fighting cells. Clusters of nodes are found in the underarm, groin, pelvis, neck, chest and abdomen.

The spleen (an organ in the upper abdomen that filters old blood cells from the blood), the thymus (a small organ beneath the breastbone), and the tonsils (an organ in the throat) are also part of the lymph system. Because lymphatic tissue occurs in all parts of the body, lymphomas can start in any tissue or organ.

There are only 5 subtypes of Hodgkin’s lymphoma but there are a multitude of subtypes of non-Hodgkin’s lymphomas. Lymphoma associated with HIV disease is usually one of the non-Hodgkin's lymphoma (NHL) subtypes.

A normal lymphocyte divides to produce many identical cells in response to certain chemical signals, but it can also stop dividing in response to certain specific chemical control signals. However, if a lymphocyte is damaged so that it does not recognise the control signals to stop cell division, it will eventually produce a mass of cells that divide uncontrollably. This mass of abnormally growing cells is a lymphoma, a tumour that can cause blockages and displace normal cells and tissue. Abnormal lymphocytes may spread to other parts of the body, where they form other tumours.

NHL occurs much more frequently in HIV-infected people than in the general population, and is most often associated with advanced disease. There are two major types of NHL in people with HIV infection:

  • Lymphoma arising in the brain and spinal cord (primary central nervous system [CNS] NHL)
  • Lymphoma arising in other parts of the body (systemic NHL).

Primary CNS NHL almost always occurs in people with very advanced HIV disease (CD4 cell count below 50/ul), whereas systemic NHL is sometimes seen in people with a decreased but slightly higher CD4 count.

Symptoms and signs of lymphoma
Lymphoma often causes fever and drenching night sweats. General tiredness, loss of appetite and significant weight loss may also occur. Further lymphoma-related symptoms depend on which areas of the body are affected.

Lymphomas commonly involve the lymph nodes, and so may be found where there are clusters of these, such as in the neck, groin or underarm area. Lymphoma may also occur in the brain and spinal cord, any part of the digestive tract, bone marrow, spleen, bone, liver, ovaries and testes. If lymphoma is present in a lymph node, the node enlarges to form a lump that is usually not painful.

If lymphoma occurs in the brain, symptoms may include confusion, memory loss, seizures, speech difficulties and headache, and numbness, tingling or weakness in the limbs.

Swollen lymph nodes do not always indicate the presence of lymphoma. HIV infection itself often causes moderate, non-tender lymph node enlargement (generalised lymphadenopathy syndrome). Also, other types of infections and certain systemic illnesses (such as rheumatoid arthritis, sarcoidosis etc.) can also produce enlarged lymph nodes.

How is lymphoma diagnosed?
Your doctor may suspect you have lymphoma if you are experiencing episodes of fever or significant sweats, symptoms indicating a CNS problem, have an enlarged lymph node or lymph node cluster, or have a mass detected on physical examination.

A radiographic study (CT Scan or MRI scan) of the brain, chest and abdomen may reveal a mass or enlarged lymph nodes that suggest lymphoma.

To prove that a mass is lymphoma requires a biopsy (tissue sample). Sometimes sufficient tissue is obtained by inserting a thin needle into the mass and drawing material into the syringe (fine needle aspiration or FNA). In most cases, however, the doctor needs to cut a small sample of tissue from the mass with a scalpel, after first providing an anaesthetic. The sample is then sent to the laboratory and examined for cancerous cells so that the subtype of lymphoma can be accurately determined.

If you have symptoms of brain involvement with a lesion visible on a CT scan of the brain, your doctor may decide to first give you medications used to treat toxoplasmosis, an infection seen in people with advanced HIV disease, to see if the tumour is not caused by toxoplasmosis. If the tumour does not shrink, CNS NHL could be the cause, and a biopsy of the lesion in the brain will then be necessary to confirm the diagnosis.

How is lymphoma treated?
All lymphomas are treatable and a large portion are curable. Effectiveness of treatment depends on the particular cell characteristics of the lymphoma, its location and how much it has spread, as well as the strength of your immune system.

Systemic NHL is treated with chemotherapy, which consists of several anti-cancer drugs given intravenously (IV) over a period of time. Side-effects from chemotherapy are common. One of the main side effects of most chemotherapy drugs is suppression of the function of the bone marrow, resulting in a low white blood cell count (neutropenia). Because of this you become very vulnerable to bacterial infections. The duration and severity of the neutropenia can be reduced by using a medication called granulocyte colony stimulating factor (G-CSF), which helps the bone marrow regenerate (recover) and produce white blood cells.

Primary CNS NHL is much more difficult to treat, and people with this disease usually do not live more than six months after diagnosis. This is because people with primary CNS NHL often have very advanced HIV disease and are at risk for severe infections and other complications. Primary CNS lymphoma is generally treated by radiation of the brain, but very high doses of chemotherapy may also be considered if you are fit enough for such intensive treatment. This may improve symptoms for a few weeks or months, but does not usually cure the tumour.

Reviewed by :Dr Adrian Schmidt MBChB(Pretoria) M Med Internal Medicine(Stellenbosch)

 

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