Lymphoma is a type of blood cancer that originates in lymphocytes, which are a type of white blood cell. Generally lymphoma occurs within the lymph nodes, which are part of the lymphatic system (a network of tissues and vessels that help control the fluid in the body) which is part of the immune system.⁷ However in some cases lymphoma can arise in other organs. This is known as extra-nodal lymphoma.

The lymphatic system is made up of lymphocytes, of which there are 2 main types: B-lymphocytes (which help to make antibodies to help protect the body from infection) and T-lymphocytes (which help to regulate the body’s immune function). ⁷

Lymphoma develops as a result of abnormal growth and development in these lymphocyte cells. There are two types of lymphoma that can occur:

• Hodgkin lymphoma (HL) – named after Dr Thomas Hodgkin who discovered the disease. It is rarer than non-Hodgkin lymphoma, and accounts for less than 1% of all cancers in New Zealand.⁴
  • Abnormal B lymphocyte cells known as Reed-Sternberg cells are the malignant cell in HL.⁷
  • Enlarged lymph nodes (most commonly around the neck) are usually noticed first.⁴
• Non-Hodgkin lymphoma (NHL) – accounts for approximately 90% of lymphomas. There are more than 60 different subtypes.⁸

Non-Hodgkin lymphoma

Non-Hodgkin lymphoma accounts for approximately 85% of all lymphoma diagnoses and is the most common type of blood cancer in New Zealand.

There are many different sub types of non-Hodgkin lymphoma which are divided into ‘B-cell’ or ‘T-cell’ lymphomas. Both sup-types are cancers of the lymphatic system after the B or T lymphocytes (type of white blood cell) undergo a malignant change and multiple uncontrollably. These abnormal cells eventually form as tumours, most commonly in the lymph nodes of the body.

Hodgkin lymphoma

Hodgkin lymphoma is a rare cancer accounting for approximately 0.5% of all cancers diagnosed in New Zealand. While non-Hodgkin lymphoma can affect either the B or T cells, Hodgkin lymphoma is marked by the presence of Reed-Sternberg cells. Reed-Sternberg cells are malignant, mature B cells, and are unusually large.

Hodgkin lymphoma tends to progress quite predictably through lymph nodes and is commonly diagnosed in early stages.

A biopsy is the only way for doctors to confirm a Hodgkin lymphoma diagnosis.

The most common system used to stage lymphoma is the Ann Arbor Staging system, which includes 4 stages;¹⁰

• Stage I – cancer cells have been found in only one group of lymph nodes
• Stage II – two or more lymph node groups have been affected; however, they are localised to either the top or bottom half of the body
• Stage III – two or more lymph node groups have been affected in both sides of the diaphragm.
• Stage IV – lymph node groups are affected as well as one or more organs (such as bone marrow or liver)