Non-Hodgkin and Hodgkin’s Lymphomas

These two diseases are called lymphomas because they originate in white blood cells called lymphocytes.

Part of the immune system, the body’s lymphatic system is our natural defence against infection and disease. It is complex and made up of bone marrow, the spleen, the thymus and the lymph nodes which are throughout the body. Lymph notes are connected by a network of tiny lymphatic vessels.

The difference between Hodgkin’s and non-Hodgkin’s is due to the specific lymphocytes involved. The distinction is made by examining the diseased cells under a microscope. Distinguishing between the two cancers is important because the treatments for Hodgkin’s and non-Hodgkin lymphomas can be quite different.

Non-Hodgkin lymphoma (NHL)

NHL is the third most common childhood cancer and occurs more often in childhood than Hodgkin lymphoma (see below). It starts in the lymphoid tissue but sometimes Non-Hodgkin lymphoma can develop outside the lymph nodes, for example, in the stomach. When NHL occurs ouside the lymph nodes, it is called extranodal lymphoma.

There are two main types of non-Hodgkin lymphoma:

• B-cell NHL (in the lymph nodes in the neck, head, throat and abdomen).
• T-cell NHL (in the lymph nodes in the chest.)

The causes of NHL are largely unknown. However, children with immune system deficiences or those who have used immuno-suppresants over a period of time are at increased risk of being diagnosed with NHL.

Hodgkin’s lymphoma

This cancer is sometimes called Hodgkin’s disease and is a cancer that starts in lymphatic tissue.

Hodgkin’s lymphoma was first described by Dr Thomas Hodgkin in 1832. It is a cancer that affects the lymphatic system. The abnormal lymphocyte involved is the B-lymphocyte which isn’t found in other types of lymphomas, which is why the other types are called non-Hodgkin’s lymphoma (see above).

Hodgkin’s lymphoma can affect children at any age, but is more common in children over 5 years old. Hodgkin lymphoma can also occur in young adults. During childhood boys are more often affected, but in the teenage years boys and girls are affected equally.

The exact cause of Hodgkin’s lymphoma is unknown. However, there is increasing evidence that infections (such as the virus that causes glandular fever) may play a part in the development of Hodgkin lymphoma.