Lymphomas are cancers of the lymphoid tissue which is part of our body's immune system.
Our immune system protects us from infection. It is a complex system made up of the bone marrow, the thymus gland (which lies behind the breast bone), the spleen and the lymph nodes (or lymph glands).
One of the most important cells in our immune system is a type of white blood cell called a lymphocyte. There are two types of lymphocytes: 'B-cells' and 'T-cells'. All lymphocytes are produced in the bone marrow and start life as young, immature cells called stem cells. Some lymphocytes continue their development in the bone marrow or lymph nodes and these are called B-cells but others move to the thymus gland and they are called T-cells.
Many years ago it was thought that lymphomas could be divided into just two conditions: Hodgkin lymphoma (named after Thomas Hodgkin, the London doctor who first described it over 100 years ago) and non-Hodgkin lymphoma (NHL). With the passage of time it has become clear that NHL is not a single illness but includes a number of cancers, which behave very differently.
The description and classification of the various types of NHL has developed over the years as more has been learnt both about the immune system and the cancers themselves. The most recent classification still recognises the difference between Hodgkin lymphoma and NHL but then goes on to divide NHL into some fifteen different tumour types.
From a practical viewpoint doctors divide all these various types of NHL into one of three groups: low grade, high grade or intermediate grade. This division is based on the appearances under the microscope and helps predict how the condition will behave.
Low grade NHLs usually have a relatively slow growth rate, running a long course and often needing little or no treatment for months or possibly years. When they do need treatment they respond well but are likely to come back again at some time in the future. They frequently respond to treatment on several occasions over the years but may eventually become resistant or transform to a high grade form of NHL.
High grade types of NHL usually grow more rapidly and behave more aggressively and so need immediate treatment. Despite this they are more likely to be completely cured than low grade NHLs. Around half of all people with high grade forms of NHL will be cured by the use of intensive chemotherapy.
Intermediate types of NHL lie somewhere between these two extremes in their behaviour.
As the precise characteristics of each of the individual subtypes of NHL are becoming better understood this 'working' classification is gradually giving way to the idea that the various subtypes of NHL are different conditions in their own right. Each of these will have different patterns of behaviour and may need different approaches to treatment.
Lymphoplasmacytic lymphoma (also called Waldenstrom's macroglobulinaemia or immunocytoma) is a uncommon form of NHL, accounting for less than 10% of all cases. It occurs in the middle aged and elderly and it affects men twice as commonly compared to women.
It is a lymphoma derived from B-lymphocytes. These lymphocytes have matured in such a way that they are half way between a lymphocyte and a plasma cell. Normal plasma cells are the cells in our immune system which produce immune globulins, the proteins that our body needs to help fight infection. The abnormal cells in lymphoplasmacytic lymphomas can also produce protein and often give rise to large amounts of abnormal immune globulins. These can be detected in the blood.
Sometimes lymphoplasmacytic lymphomas produce so much abnormal immune globulin that the extra protein actually thickens the blood. This can leads to a condition called hyperviscosity syndrome.
The first sign of the condition is usually the development of anaemia. Sometimes bruising occurs due to a low platelet count in the blood. Both the anaemia and the low platelet count are the result of large numbers of the abnormal plasma cells in the bone marrow which interfere with the production of normal red blood cells and platelets. In contrast to most other types of lymphoma, enlargement of the lymph nodes is not a prominent feature of the disease. Other symptoms may include night sweats, unexplained fever, loss of appetite, or weight loss and discomfort due to an enlarged spleen.
If a hyperviscosity syndrome develops the thickening of the blood results in less oxygen being transferred to vital organs and can cause dizziness, headache, shortness of breath and confusion. Visual disturbance is also very common due to the blood flow in the tiny blood vessels of the retina, at the back of the eye, being affected.
The diagnosis is made by blood tests and the analysis of a sample of tissue taken from the bone marrow.
Lymphoplasmacytic lymphoma is a low grade lymphoma and usually only progresses very slowly. Because of this treatment is often delayed until the condition causes symptoms.