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Lymphoma Explained

What is cancer?

Cells make up every part of the human body including our skin, hair, nails, lymph nodes, blood and body organs. Cell division is a normal part of a cell’s life cycle and is regulated by our genes (segments of DNA that determine a person’s unique characteristics and how their body functions). Under healthy conditions, the process of cell division is tightly controlled with numerous checks and balances in place. The definition of cancer is the abnormal, uncontrolled growth of cells.

Why does cancer occur?

This is a question that scientists have been trying to answer for a long time. One main reason that cancer may develop is due to genetic errors. There are many different genes present in all cells and each one controls a different function in the body. When errors occur in the genes (called genetic mutations) that control cell division, the result is a cell that cannot divide normally. This results in an abnormal cell that cannot properly perform its intended function. The cells of the immune system are constantly circulating in the body to identify and destroy these abnormal cells. However, in instances where the immune system does not work properly, or if the genetic mutation is too severe, these abnormal cells remain and grow at an uncontrolled rate. Cancer is what occurs when these abnormal cells continue to grow at an uncontrolled rate. As these abnormal cells divide, they can create their own blood supply and form a solid mass called a tumour. A cancerous tumour will continue to grow at an uncontrolled rate and will eventually cause harm to other areas of the body.

What is the lymphatic system?

The lymphatic system is a system of lymph nodes, vessels and organs that runs throughout the body, and often seems mysterious and elusive as it does not receive the same attention as other body systems, like the cardiovascular or digestive systems. Individuals may be aware of lymph nodes in the neck when they become swollen with a sore throat or infection. The lymphatic system is a very important part of the body serving many life-preserving functions.

The lymphatic system is a network primarily made up of:

  • Lymph nodes: small, bean-shaped organs found throughout the body; and
  • Lymphatic vessels: vessels which circulate lymphatic fluid (also called lymph) throughout the body


  • Bone marrow
  • Thymus gland
  • Tonsils
  • Spleen
  • Liver
  • Lymphocyte accumulations in the lining of the intestinal, respiratory, genital and urinary 


How does the lymphatic system work?

The lymphatic system has three main functions:

  1. To circulate and regulate fluid levels in the body. Any excess fluid that escapes from the bloodstream is picked up by the lymphatic system and returned to the blood stream. This helps to prevent oedema (swelling due to excess fluid) and keeps the fluid levels in the body and the bloodstream within normal limits.
  2. To absorb fats from the digestive system. Special lymph vessels, called lacteals, are located in the lining of the digestive system where they are responsible for absorbing fat and fat-soluble vitamins from food. The fats are then transported to the bloodstream and used as needed.
  3. To defend the body against infection. The vessels of the lymphatic system move lymphatic fluid and lymphocytes, a specific type of white blood cell, throughout the body. The lymphatic fluid travelling through the lymphatic vessels passes through lymph nodes, which are primarily made up of lymphocytes. The lymphocytes serve to filter the lymphatic fluid of any debris, removing bacteria, viruses and other foreign substances. This helps keep the body free of invading organisms and therefore, free of infection.

What are Lymphocytes?

Lymphocytes are a type of white blood cell and are a major component of the lymphatic system. Lymphocytes are divided into two types: B-lymphocytes or T-lymphocytes (also called B-cells or T-cells), and function to fight infection and prevent disease. They are an integral part of a healthy immune system. 

Normal functioning B-cells transform into highly specialised cells called plasma cells in the face of infection. Plasma cells manufacture antibodies which function to fight infections. T-cells directly attack foreign invaders such as bacteria and viruses, and also kill cancer cells and rid them from the body. Lymphocytes can be found in the blood however, the majority of them are normally circulating within the lymphatic system.

What is lymphoma?

Lymphoma is a cancer of the lymphatic system so understanding the lymphatic system and cancer in general makes it easier to understand. In lymphoma, a tumour develops due to uncontrolled growth of abnormal lymphocytes. Because the lymphatic system exists throughout the body and involves many organs, there may be cancerous tumours in many parts of the body when someone has lymphoma. There are two main categories of lymphoma: Hodgkin Lymphoma (HL) and Non-Hodgkin Lymphoma (NHL).

What is the difference between Hodgkin and Non-Hodgkin Lymphoma?

The difference between Hodgkin Lymphoma and Non-Hodgkin Lymphoma is the presence of Reed-Sternberg cells. A Reed-Sternberg cell is a cell derived from a B-lymphocyte and is only present in Hodgkin Lymphoma. If Reed-Sternberg cells are present when the tumour is examined under a microscope, the diagnosis is Hodgkin Lymphoma. If there are no Reed-Sternberg cells in a lymphatic tumour, the diagnosis is most likely to be Non-Hodgkin Lymphoma. 

Of all diagnosed lymphoma cases, 90% of them are Non-Hodgkin Lymphoma and 10% Hodgkin Lymphoma. Distinguishing between Hodgkin Lymphoma and Non-Hodgkin Lymphoma is important.

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