Types of Non-Hodgkin's Lymphoma

Because there are so many types of non-Hodgkin’s lymphoma, several different systems have been developed to classify this disease. Most doctors now use the REAL/WHO classification (Revised European-American Lymphoma/World Health Organization). The REAL/WHO system sorts the types of lymphoma by the appearance of the lymphoma cells, presence of proteins on the surface of the cells, and genetic features. Although there are many kinds of lymphomas, only the most common types are discussed below.

To simplify discussion of non-Hodgkin’s lymphomas, the many specific types are sometimes grouped together into slow growing (or indolent), aggressive, or highly aggressive categories (see Table 1). Aggressive and highly aggressive lymphomas grow more rapidly and spread through the body quickly. Without treatment, most patients live only a short time. Fortunately, most aggressive and highly aggressive lymphomas respond well to chemotherapy, and many can be cured.

Table 1. Lymphoma types (based on how they grow)

* Although mantle cell lymphoma is not very fast growing, it responds poorly to standard treatment

B-Cell Lymphomas

Chronic lymphocytic leukemia/small lymphocytic lymphoma: Although one disease is a leukemia and one is a lymphoma, these two diseases are related and account for 7% of all lymphomas. In both kinds, the same type of cell, the small lymphocyte, is involved. The only difference is in where the cancer occurs. It is mostly in the blood in leukemia, and it is mainly in the lymph nodes in lymphoma. Both are slow-growing diseases although leukemia, which is much more common, tends to be slower. They are not considered curable with standard treatments. But depending on the stage and growth rate of the disease, patients can live well over 10 years with this lymphoma.

Recently it has become clear that there are 2 kinds of chronic lymphocytic leukemia. One is very slow growing and rarely needs treatment. The other kind grows faster and almost always needs to be treated. Doctors can tell them apart by testing for a substance called ZAP-70 in the leukemia cells. This is a new test that is not available everywhere. Cells that contain this substance are usually the faster growing kind. Sometimes, these slow-growing lymphomas can change (transform) over time into a more aggressive type of lymphoma.

Follicular lymphoma: About 22% of all lymphomas are follicular lymphomas. These cells tend to grow in a nodular pattern similar to the normal patterns in lymph nodes. This is a slow growing lymphoma. It mostly arises in many lymph node sites in the body, as well as in the bone marrow. The average age for people with this lymphoma is 60. It is rare in very young people. In advanced stages it is not considered curable by standard treatment. The percentage of patients who live at least 5 years after their cancer is diagnosed is about 60% to 70%. In time, many follicular lymphomas transform into a fast growing diffuse large B-cell lymphoma.

Extranodal marginal zone B-cell lymphomas - mucosa-associated lymphoid tissue (MALT) lymphomas: This type makes up 8% of lymphomas. Most MALT lymphomas start in the stomach. They are thought to stem from an infection by bacteria called Helicobacter pylori. This lymphoma can also develop in other sites like lung, skin, thyroid, salivary gland, small or large intestine, breast, and tissues surrounding the eye. In those cases, the cancer is called nongastric MALT lymphoma. Usually MALT lymphomas are confined to the area where they began and are not widespread. The average age for patients with this lymphoma is 60. It is a slow-growing lymphoma and often can be put into prolonged remission and possibly cured in its early stages.

Mantle cell lymphoma: About 6% of lymphomas are this type. When diagnosed, it is usually widespread and will involve lymph nodes, bone marrow, and, very often, the spleen. Men are most often affected; the average age of patients is in the early 60s. Although this is not a very fast growing lymphoma, it is a serious one. Only 20% of patients survive at least 5 years.

Diffuse large B-cell lymphoma: This kind makes up 31% of all lymphomas. It is a fast-growing lymphoma. The usual symptoms are a rapidly growing mass in the body or in a lymph node that can be felt. About one-third of these lymphomas are confined to one part of the body (localized). Although this lymphoma usually starts in lymph nodes, it can grow in other areas such as the intestines, bone, and the brain or spinal cord. When it is localized this type of lymphoma is considered to be more curable than when it has spread to other parts of the body. It can affect any age group but mostly occurs in older people. The average age of patients is the mid-60s. About 40% to 50% of people with this lymphoma are cured with treatment.

Burkitt’s lymphoma: This type makes up about 2% of all lymphomas. It is named after the doctor who first described this disease in African children and young adults. Another kind of lymphoma called Burkitt’s-like lymphoma looks like Burkitt’s lymphoma but the cells are slightly larger. Because they are hard to tell apart, the REAL/WHO classification combines them. In the African type, it often starts as tumors of the jaws or other facial bones. In the more common types seen in the United States, the lymphoma usually starts in the abdomen, where it forms a large tumor mass. It can also spread to the brain and spinal fluid. The average age of patients is about 30, and close to 90% of patients are male. Although this is a fast-growing lymphoma, about half of patients are cured by aggressive chemotherapy.

AIDS-related B-cell lymphoma: The major types of non-Hodgkin’s lymphoma seen in people with AIDS are diffuse large B-cell lymphoma, Burkitt’s lymphoma, and primary central nervous system lymphoma. The first two are discussed above. The main difference in treating these lymphomas in people with AIDS is that often their outcome depends on how well the AIDS is responding to treatment. Also, these patients are very sensitive to the side effects of chemotherapy, especially the effect on blood counts. This is becoming less of a problem because of advances in treating the HIV infection that causes AIDS. Also, the number of people developing these lymphomas has decreased in the last few years because of the improved HIV treatment.

Primary central nervous system lymphoma: This lymphoma usually involves the brain (then called primary brain lymphoma), but it also can be found in the spinal cord and in tissues around the spinal cord and inside the eye. In time, it spreads throughout the central nervous system. In the past, this was a rare tumor, but it has become more common with the AIDS epidemic. Most people develop headache and confusion. They can also have vision problems and, rarely, paralysis. The outlook for people with this condition is poor. About 30% of people can live 5 years with modern treatments.

T-Cell Lymphomas

Anaplastic large T/null-cell lymphoma: About 2% of lymphomas are this kind. The cells are large. It is more common in young people. It usually starts in lymph nodes and can also spread to skin. There is one form that begins in the skin. Although this type of lymphoma appears to be fast growing, treatment with chemotherapy or radiotherapy is often successful, especially if the tumor cells contain a protein called ALK-1. Many patients with this lymphoma are cured. It is generally treated like a diffuse large B-cell lymphoma.

Peripheral T-cell lymphomas: There are several kinds of peripheral T-cell lymphomas, which, in total, account for about 7% of all lymphomas. They are mostly treated like diffuse large B-cell lymphomas. There are a variety of rare subtypes of these lymphomas which include:

• Histology unspecified: Extranodal natural killer/T-cell lymphoma, nasal type which often involves the upper airway passages, such as the nose and nasopharynx, but also invades the skin and gastrointestinal tract.
• Enteropathy type T-cell lymphoma which can occur in people who are sensitive to gluten, the main protein in wheat flour.
• Subcutaneous panniculitis-like T-cell lymphoma which invades the deepest layers of the skin and causes nodules to form under the skin.

Lymphoblastic lymphoma/leukemia: This type can be either B cell or T cell. This disease can be considered either a lymphoma or leukemia, depending on whether more (leukemia) or less (lymphoma) than 25% of bone marrow cells are lymphoma cells. Usually the lymphoma forms in the mediastinum (the area in front of the heart and behind the chest bone). About 2% of all lymphomas fall into this group. Patients are most often (75%) men, and their average age is 25. The cell is small to middle-sized. The lymphoma is fast growing, but if it hasn’t spread to the bone marrow when first diagnosed, the chance of cure with chemotherapy is quite good.

INTRODUCTION

WORK UP

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