What is Hodgkin lymphoma?
Hodgkin lymphoma is a type of lymphoma, which is a general term for cancer of the lymphatic system. It is sometimes called Hodgkin disease. The name Hodgkin comes from the doctor who first described this cancer.
“A few months before my wedding in 2005, I saw my GP as I’d been feeling tired and had lost weight, but I was mostly worried about a lump in my neck. The doctor didn’t have time to check it out properly and wasn’t too worried, so I didn’t think anything else of it.”
Hodgkin lymphoma develops when lymphocytes become damaged. The lymphocytes grow and multiply uncontrollably, causing enlarged lymph nodes and painless lumps called tumours. As the damaged lymphocytes replace normal lymphocytes, the body’s immune system becomes less able to resist and fight infections.
Hodgkin lymphoma may affect a single lymph node, a group of lymph nodes, or an organ such as the liver, lung, spleen or bone marrow. Sometimes Hodgkin lymphoma can appear in several parts of the body at the same time.
Topics on this page:
- The lymphatic system
- Types of Hodgkin lymphoma
- What causes Hodgkin lymphoma?
- Who gets Hodgkin lymphoma?
The lymphatic system
Hodgkin lymphoma is a cancer of the lymphatic system. The lymphatic system is part of the immune system, which protects the body against disease and infection.
The lymphatic system includes a large network of thin tubes (lymph vessels) that are found throughout the body and in a number of organs, such as the spleen, liver, thymus gland and bone marrow.
Lymph vessels carry a clear fluid called lymph. This fluid travels to and from the tissues before being emptied into the bloodstream. Lymph contains white blood cells called lymphocytes, which help fight infection.
Along the lymph vessels is a network of small, bean-shaped structures called lymph nodes or glands. Lymph nodes are found throughout the body, including the neck, underarms, chest, abdomen and groin.
The lymphocytes in the lymph nodes clean the lymph fluid as it passes through the body by removing and destroying bacteria, viruses and other harmful substances.
When germs become trapped in the lymph nodes, they become swollen, which is a sign that your body is fighting an infection. For example, the glands in your neck may swell when you have a sore throat. The swelling happens because the lymphocytes in the lymph nodes multiply to fight off the virus or bacteria that is causing the infection.
Other parts of the lymphatic system include:
- Spleen – The spleen is found on the left side of the abdomen, under the ribs. It stores lymphocytes, filters waste products from the blood, and destroys old blood cells, abnormal cells and bacteria.
- Thymus gland – This is found inside the rib cage, behind the breastbone. The thymus gland helps produce white blood cells.
- Tonsils – The tonsils are a collection of lymphatic tissue at the back of the throat that traps inhaled or ingested germs.
- Bone marrow – This is the soft, spongy material inside bones. Bone marrow produces three types of blood cells: oxygen- carrying red blood cells; infection-fighting white blood cells, including lymphocytes; and platelets, which help the blood to clot.
Types of Hodgkin lymphoma
There are two different types of Hodgkin lymphoma: classical Hodgkin lymphoma and nodular lymphocyte-predominant Hodgkin lymphoma. These two types differ in how they look under the microscope and how they grow and spread.
Classical Hodgkin lymphoma
About 95% of all cases of Hodgkin lymphoma are classical Hodgkin lymphoma. The cells of this type of Hodgkin lymphoma are called Reed-Sternberg cells.
There are four subtypes of classical Hodgkin lymphoma. Each one has a unique appearance under a microscope. They grow differently and involve different sites of the body.
- Nodular sclerosing – the most common subtype of classical Hodgkin lymphoma. It affects 60–80% of people with Hodgkin lymphoma. This subtype affects more women than men.
- Mixed cellularity – affects 25–30% of people.
- Lymphocyte-rich – affects 5% of people.
- Lymphocyte-depleted – affects fewer than 5% of people.
Nodular lymphocyte-predominant Hodgkin lymphoma
The cells of nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) are called ‘popcorn cells’ because of the way they look under a microscope.
NLPHL occurs in fewer than 5% of people with Hodgkin lymphoma. It mostly affects men in their 30s and 40s.
The main symptom of NLPHL is enlarged lymph nodes in the neck, chest or armpit. It is usually diagnosed via biopsy.
Sometimes, an operation to remove the lymph nodes is the only treatment for NLPHL. This is followed by ‘watch and wait’, which involves regular check-ups to make sure the cancer hasn’t returned.
What causes Hodgkin lymphoma?
The causes of Hodgkin lymphoma are largely unknown. Researchers think a combination of factors relating to a person’s genes and from their environment may cause Hodgkin lymphoma. Risk factors include:
Epstein-Barr virus and HIV – People who have a history of Epstein-Barr virus infection (also called glandular fever or infectious mononucleosis) or HIV infection have a higher chance of developing classical Hodgkin lymphoma. However, this accounts for few people who have Hodgkin lymphoma.
Family history – Having a parent, brother or sister who has had Hodgkin lymphoma slightly increases a person’s risk of developing it. However, this family link is uncommon, as most people with Hodgkin lymphoma do not have a family history.
Lifestyle factors – Being overweight or obese increases a person’s risk of developing Hodgkin lymphoma. Smoking is also a risk factor.
Many people with known risk factors don’t develop Hodgkin lymphoma, and some people who do get it have no known risk factors. Hodgkin lymphoma is not contagious.
Who gets Hodgkin lymphoma?
Hodgkin lymphoma is a rare form of cancer – it makes up only about 0.5% of all cancers diagnosed in Australia.
About 12% of all lymphomas diagnosed are types of Hodgkin lymphoma. The rest are non-Hodgkin lymphomas.
Each year in NSW, about 180 people are diagnosed with Hodgkin lymphoma. It most commonly develops in younger people aged 14–29 and older people aged over 50, but it can occur at any age. It is more common in men than women.