The Technical Details - http://www.cancer.gov/cancertopics/wyntk/hodgkin

To make it somewhat easier for the readers I have borrowed the basics of Hodgkins from the listed website. For an excellent and really comprehensive overview please view the listed web page.

What Is Hodgkin Lymphoma?

Hodgkin lymphoma is a cancer that begins in cells of the immune system. The immune system fights infections and other diseases.

The lymphatic system is part of the immune system. The lymphatic system includes the following:

• Lymph vessels: The lymphatic system has a network of lymph vessels. Lymph vessels branch into all the tissues of the body.
• Lymph: The lymph vessels carry clear fluid called lymph. Lymph contains white blood cells, especially lymphocytes such as B cells and T cells.
• Lymph nodes: Lymph vessels are connected to small, round masses of tissue called lymph nodes. Groups of lymph nodes are found in the neck, underarms, chest, abdomen, and groin. Lymph nodes store white blood cells. They trap and remove bacteria or other harmful substances that may be in the lymph.
• Other parts of the lymphatic system: Other parts of the lymphatic system include the tonsils, thymus, and spleen. Lymphatic tissue is also found in other parts of the body including the stomach, skin, and small intestine.

Because lymphatic tissue is in many parts of the body, Hodgkin lymphoma can start almost anywhere. Usually, it's first found in a lymph node above the diaphragm, the thin muscle that separates the chest from the abdomen. But Hodgkin lymphoma also may be found in a group of lymph nodes. Sometimes it starts in other parts of the lymphatic system.

Hodgkin Lymphoma Cells

Hodgkin lymphoma begins when a lymphocyte (usually a B cell) becomes abnormal. The abnormal cell is called a Reed-Sternberg cell.

The Reed-Sternberg cell divides to make copies of itself. The new cells divide again and again, making more and more abnormal cells. The abnormal cells don't die when they should. They don't protect the body from infections or other diseases. The build up of extra cells often forms a mass of tissue called a growth or tumours.

The doctor considers the following to determine the stage of Hodgkin lymphoma:

The number of lymph nodes that have Hodgkin lymphoma cells

Whether these lymph nodes are on one or both sides of the diaphragm

Whether the disease has spread to the bone marrow, spleen, liver, or lung.

 The stages of Hodgkin lymphoma are as follows:

1. Stage I: The lymphoma cells are in one lymph node group (such as in the neck or underarm). Or, if the lymphoma cells are not in the lymph nodes, they are in only one part of a tissue or an organ (such as the lung).
2. Stage II: The lymphoma cells are in at least two lymph node groups on the same side of (either above or below) the diaphragm. Or, the lymphoma cells are in one part of a tissue or an organ and the lymph nodes near that organ (on the same side of the diaphragm). There may be lymphoma cells in other lymph node groups on the same side of the diaphragm.
3. Stage III: The lymphoma cells are in lymph nodes above and below the diaphragm. Lymphoma also may be found in one part of a tissue or an organ (such as the liver, lung, or bone) near these lymph node groups. It may also be found in the spleen.
4. Stage IV: Lymphoma cells are found in several parts of one or more organs or tissues. Or, the lymphoma is in an organ (such as the liver, lung, or bone) and in distant lymph nodes.

Recurrent: The disease returns after treatment.

In addition to these stage numbers, your doctor may also describe the stage as A or B:

A: You have not had weight loss, drenching night sweats, or fevers.

B: You have had weight loss, drenching night sweats, or fevers