Lymphoma

Hodgkin's Disease and Non-Hodgkin's Lymphoma Symptoms Image

What is a Lymphoma?

A lymphoma is a malignant tumor of the lymphatic system. It is also the name for cancer of the lymphatic system.

Although the description “lymphoma” covers a mixed group of diseases, the two main types of cancer of the lymphatic system are Hodgkin’s disease (HD or HL) and non-Hodgkin’s lymphoma (NHL). As few as eight percent of lymphomas diagnosed each year in the United States are classified as Hodgkin’s disease.

Cancerous lymph cells can occur anywhere in the body where there are lymphocytes (a type of white blood cell). Malignancies are most likely to develop in the lymph nodes of the neck, tonsils, under the jaw, thymus gland, armpits, elbows, groin, legs, ankles, spleen and bone marrow. Abnormal cells, however, may also occur in other organs of the body, such as the central nervous system and the gastrointestinal tract.

Also, it is not uncommon, in more advanced cases, for the cancer to spread to other parts of the body outside the lymphatic system, such as the lungs and liver. HD tends to spread from one lymph node to an adjacent node, but it can also spread to organs outside the lymphatic system, whereas NHL often skips, randomly, to other parts of the body.

What is Lymphoma - Lymphoma

Similarities and Differences to Leukemia

Leukemia is a cancer that originates in the bone marrow. As with lymphoma, it involves the abnormal growth of white cells.

Another similarity between the two forms of cancer is that the malignant cells multiply to an extent that they impede the production of healthy blood cells, thus leading to a weakening of the body’s immune system.

Unlike leukemia, however, which originates in the bone marrow, lymphomas start in the lymphoid tissues, typically in the lymph nodes, in various parts of the body.

The Importance of the Lymphatic System

The lymphatic system protects the body from disease. Its proper functioning is vital to maintaining a healthy immune system.

The lymphatic system consists of several narrow tubes called lymph vessels. These vessels form a network that extends throughout the body. The lymphatic system carries a fluid called “lymph” that contains white blood cells called lymphocytes.

Lymph nodes look a bit like small bean-shaped protrusions and are located throughout the lymphatic system. One of the most common lymphoma symptoms is a persistent swelling of the lymphatic tissue in the lymph nodes. Most instances of swollen lymph nodes, however, are not cancerous, but merely the body’s reaction to a minor infection.

Classification

Recent advances in the diagnosis and treatment of NHL have led to improved methods for classifying subtypes of this group of diseases. Current thinking favors the new WHO (2000) classification of lymphoid tumors, which is based on the Revised European-American Classification of Lymphoid Neoplasms (REAL), originally published in 1994.

This new classification system groups tumors according to morphological (how the cells look), phenotypic (what proteins the cells produce), and genotypic (the presence of specific genetic mutations) characteristics.

In addition, lymphomas may be classified as aggressive (fast growing) or indolent (slow growing). This additional classification is referred to as the grade of the tumor.

Classification also generally involves grouping subtypes according to cell types such as T-Cells, B-Cells, Large Cells or Follicular Cells.

HD Subtypes

Hodgkin’s disease is classified according to the appearance of the abnormal cells under the microscope. The disease is subdivided into four main types. The two most common subtypes of HD are Nodular Sclerosis and Mixed Cellularity. Less common subtypes are Lymphocyte Predominant and Lymphocyte Depleted, with the latter accounting for as few as five percent of Hodgkin’s lymphomas.

NHL Subtypes

As with Hodgkin’s disease, NHL is also classified by examining cell tissues under a microscope. Each type of NHL is further classified according to growth rate.

Common subtypes of NHL include diffuse large B-cell, precursor T lymphoblastic, mantle cell, follicular, marginal Zone B-cell, MALT-type, Burkitt’s lymphoma, and mycosis fungoides/Sezary’s syndrome, to name but a few.

Resources

Cancer Research UK. (nd). Hodgkin’s disease. Retrieved April 14, 2003, from www.cancerresearchuk.org/aboutcancer/specificcancers/23387.

Cancer Research UK. (nd). Non-Hodgkin’s lymphoma. Retrieved April 14, 2003, from www.cancerresearchuk.org/aboutcancer/specificcancers/15222.

Lymphoma Research Foundation. (2002). Learn about lymphoma. Retrieved April 14, 2003, from www.lymphoma.org/site/PageServer?pagename=learning