Lymphoma is a type of blood cancer that affects white blood cells called lymphocytes. Lymphocytes are in your blood, as well as your lymph nodes, spleen, bone marrow, and other parts of the body that make up your lymphatic system. There are two main types of lymphocytes: B lymphocytes and T lymphocytes, also called ‘B cells’ and ‘T cells.’ The two main types of lymphoma are Hodgkin lymphoma (also called Hodgkin’s disease) and non-Hodgkin lymphoma. Both types have several subtypes, which present their own challenges for diagnosis and treatment. Different types of lymphoma affect some age groups more than other ages. It’s important to know the type and subtype of lymphoma because it affects prognosis and identifies what types of treatments may be available. Hodgkin Lymphoma Every year, more than 8,000 people in the United States are diagnosed with Hodgkin lymphoma. Treatment is improving and more people are surviving, but about 1,000 people will still die from the disease this year. Hodgkin lymphoma can occur at any age, but it is most common among young adults aged 15 to 40 years and adults older than 55. It’s the most common cancer diagnosed among teens from 15 to 19 years. With Hodgkin lymphoma, the lymph node has abnormal cells called Reed-Sternberg cells. The name Hodgkin lymphoma is just the first part of identifying the disease. There are two main subtypes: classical Hodgkin lymphoma and nodular lymphocyte-predominant Hodgkin lymphoma. Classical Hodgkin lymphoma (CHL) is the most common type of Hodgkin lymphoma, affecting more than 90% of people diagnosed with the disease. It is further divided into four subtypes. The shape of the lymphoma cells and other characteristics determine each subtype. The subgroups are: Nodular sclerosis CHL: The most common form of Hodgkin lymphoma, affecting 60 to 80% of people with the disease. More women than men develop nodular sclerosis CHL but it is highly curable with the right treatment approach. Mixed cellularity CHL: This is a less common subtype of CHL, affecting 15 to 30% of people with Hodgkin lymphoma, more men than women, and mostly older adults. It can be harder to cure because it is often diagnosed later than nodular sclerosis CHL. Lymphocyte-depleted CHL: An aggressive form of Hodgkin lymphoma, lymphocyte-depleted CHL is quite rare—as low as 1% or less of all Hodgkin lymphoma cases. It is difficult to treat because it spreads quickly and diagnosis often comes later when it is advanced. People most likely to have this subtype include those who are older or have HIV, and people in developing countries. Lymphocyte-rich CHL: Affecting about 5% of all people with Hodgkin lymphoma, lymphocyte-rich CHL has a high cure rate with few relapses. It’s often diagnosed early, in stage I or II, making treatment more effective. It is more common in men. Hodgkin lymphoma is among the most curable of cancers if it is caught early enough. If treatment or diagnosis is delayed, it can spread to the spleen, liver, bone marrow, or bone. The treatment for Hodgkin lymphoma depends on the subtype and the stage—how far along the cancer has progressed. Non-Hodgkin Lymphoma Non-Hodgkin lymphoma is more common than Hodgkin lymphoma. It affects almost 75,000 people in the United States each year. More than half of those who develop non-Hodgkin lymphoma are older than 65. It differs from Hodgkin lymphoma because it does not have the Reed-Sternberg cell. Most often, non-Hodgkin lymphoma begins in the lymph nodes, but it can start elsewhere. There are many subtypes of the disease. The most common is B-cell lymphoma. About 80% of patients with non-Hodgkin lymphoma have this subtype. T-cell lymphoma makes up about 15% of non-Hodgkin lymphoma cases. B-cell lymphomas include these: Diffuse large B-cell lymphoma: This most common type of non-Hodgkin lymphoma affects people of all ages, particularly middle age and older adults. Caucasians are at higher risk for developing this type of lymphoma than African Americans or Asian Americans. Follicular lymphoma: This is the second-most common form of non-Hodgkin lymphoma. It usually strikes older people, over the age of 50. Follicular lymphoma is often diagnosed later, when it is already at stage 3 or 4, which makes the survival rate lower than lymphomas diagnosed earlier. Marginal zone lymphoma: About 8% of non-Hodgkin lymphoma cases are marginal zone lymphoma (MZL). It often strikes people aged 60 or older. One subtype, extranodal MZL or mucosa-associated lymphoid tissue (MALT) often occurs in people who have had previous chronic infections, chronic inflammation, or autoimmune disorders. A second subtype, splenic MZL, frequently affects people with hepatitis C infection. Mantle cell lymphoma: Mantle cell lymphoma affects about 6% of people with non-Hodgkin lymphoma. It is an aggressive form of the disease and is usually diagnosed late. Waldenström’s macroglobulinemia: Fewer than 2% of cases are this subtype, which is a slow-growing cancer that affects mostly older adults. Burkitt lymphoma: This is a rare but very aggressive type of non-Hodgkin lymphoma. There are two subtypes. Sporadic Burkitt lymphoma affects up to 30% of children with B-cell non-Hodgkin lymphoma; it is rare among adults. Immunodeficiency-related Burkitt lymphoma affects mostly people with HIV, but it can also strike people who have a weakened immune system. Primary mediastinal B-cell lymphoma:This subtype affects mostly young adults and is relatively rare, affecting between 2% and 4% of people with the disease. Primary mediastinal B-cell lymphoma affects more women than men. It is a fast-growing cancer that can spread to the tissues and organs in the chest cavity. It shares many features with classical Hodgkin lymphoma. Small lymphocytic lymphoma: This subtype represents about 5% of all non-Hodgkin lymphoma cases. SLL is considered the same disease as chronic lymphocytic leukemia (CLL is the most common form of adult leukemia). The difference is when most of the cancerous lymphocytes are in the lymph nodes it is diagnosed SLL and when most of them are in the bone marrow it is CLL. Some forms grow slowly and treatment may only be necessary when symptoms occur or when tests show faster cancer growth. Subtypes of T-cell lymphomas include: T-lymphoblastic lymphoma/leukemia: Most common in teens and young adults, T-LBL affects about 1% of people with lymphoma. It affects more men than women. This type of lymphoma differs from the others because it can be either lymphoma or leukemia, a type of blood cancer that starts in the bone marrow. The final diagnosis depends on how much of the bone marrow is involved. Peripheral T-cell lymphoma: A rare, aggressive form of non-Hodgkin lymphoma. There are eight subtypes. Lymphoma treatment teams may use chemotherapy, immunotherapy, and radiation therapy to remove the abnormal lymphocytes. Some people with lymphoma are treated with bone marrow transplants, others are candidates for stem cell transplants. Which type of therapy you may receive depends on what type of lymphoma you have (Hodgkin disease versus non-Hodgkin disease), what subtype, how far it has progressed, and the benefits, risks and side effects of treatment.