We have discussed leukemia and how it begins in the blood cell lines of the bone marrow, but we have yet to discuss another cancer of blood cells called lymphoma. Lymphoma is cancer of the lymphocytes (infection fighting cells) that develops and divides locally in lymph nodes. We are going to discuss malignant lymphomas that can be divided into two categories: non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL).

Non-Hodgkin Lymphoma (NHL) is more common and usually seen in patients older than 50. NHL can be classified as B-cell, T-cell, or even NK-cell lymphoma. Depending on the type of NHL either humoral or cell-mediated immunity is disrupted. B-cell lymphoma is most common in the United States (~90% of cases), hence humoral immunity is more commonly affected. Non-Hodgkin lymphoma is more life-threatening because it spreads faster and to other organs more than HL. Risk factors for NHL include chemical and radiation exposure and immune dysfunction. Genetics, impaired immunity and infectious agents all play roles in causing NHL. Gene changes related to NHL are usually acquired during life rather than being inherited. People with immune deficiencies and autoimmune diseases have a much higher chance of getting NHL because they have weakened immune systems. Chronic infections also pose an increased risk because the body is always making new lymphocytes to fight infection, so there are more chances for a mutation in lymphocyte DNA to occur.

Hodgkin Lymphoma (HL) spreads from lymph node to lymph node and is therefore more predictable. Those with HL will have poor cell-mediated immunity. Large leukocytes found in the superficial cortex of lymph nodes called Reed Sternburg cells are characteristic of HL and are critical in diagnosis. Viruses, carcinogens, and genetics can all cause HL. Staging is an important diagnostic test for HL and helps the healthcare provider know the location and number of nodes involved in the lymphomas. Stage A HL is characterized by the patient having no constitutional symptoms while stage B HL is characterized by weight loss and night sweats.