Lymphoma is a group of blood cancers that start in the lymphatic system. The lymphatic system carries lymph, a watery, colorless fluid and white blood cells throughout body through a system of vessels. The primary job of the lymph system is to fight infection inside the body by filtering out viruses, microbial bacterium and other harmful agents.
When lymphoma occurs, the white blood cells within the lymph fluid, called lymphocytes, are in a state of uncontrollable growth and multiplication. These cancerous cells can then spread to other parts of the body by moving through the lymphatic system.
There are two main types of lymphoma, Hodgkin lymphoma (sometimes called Hodgkin’s disease and named for Dr. Thomas Hodgkin who first described it in 1832) and non-Hodgkin lymphoma (NHL). Each type has characteristics that are similar and those that are so unique as to distinguish it from other diseases classified as lymphoma.
While lymphoma causes many different signs and symptoms, some people may have no symptoms at all until the tumor grows quite large. Symptoms vary to the type of lymphoma a person has and in which part of the lymph system the disease starts. Generalized symptoms include weight loss without a known reason, fever and heavy night sweating. In faster growing lymphomas, a person with low blood counts may experience severe or frequent infections, easy bruising or bleeding, fatigue and/or anemia.
One distinguishing difference between the two main lymphoma types is the white blood cells involved. Each type looks different under a microscope, although sometimes tests are needed to confirm a diagnosis. Hodgkin lymphoma starts when normal white blood cells (usually B cells) become abnormal, super-sized Reed-Sternberg cells. These gigantic cells not only rapidly reproduce, but also tend to live longer than normal cells. The abnormal cells eventually become so plentiful they form tumors. However, Hodgkin lymphoma is one of the most curable forms of cancer.
In non-Hodgkin lymphoma, a B cell type of cancer cell is also typical in about 85 percent of diagnoses, but looks different than the Reed-Sternberg cells.