Lymphoma refers to a form of tumor caused by the immune system, involving abnormal activity of lymphocytes, body cells that belong to the lymphatic system. Lymphocytes are born at the level of the bone marrow and their primary role inside the body is to identify antigens (foreign bodies that are malignant to the organism) and to trigger the action of the immune system, telling it to attack the discovered antigens. However, in the case of patients with lymphoma, the cells of the lymphatic system become compromised and begin to act like cancer cells. Thus, the occurrence of lymphoma is primarily determined by inappropriate activity of the lymphatic system, lymphocytes multiplying at abnormally fast rates and accumulating in different regions of the body.

There are two distinctive types of lymphatic cells involved in causing the occurrence of lymphoma: ?B? lymphocytes and 'T' lymphocytes (commonly referred to as B cells and T cells). The main action of B cells is to create antibodies, a type of proteins that fight against antigens. The T cells (born at the level of the thymus gland) help the activity of the B cells, sustaining and enhancing their action.

According to the type of cells involved in causing the disease and the rate of progression, there are multiple forms of lymphoma. The main two types of lymphoma are: Hodgkin's Lymphoma (also referred to as Hodgkin's Disease) and Non-Hodgkin's Lymphoma. These two main types can be further classified in multiple subtypes. Hodgkin's Lymphoma is characterized by the implication of the so-called ?double-eyed cells? in causing the disease. All other varieties of lymphoma that don't share this feature are known as Non-Hodgkin's Lymphomas. Non-Hodgkin's Lymphoma comprises over 25 subtypes, classified according to the speed of progression and the seriousness of the disease. Various subtypes of lymphoma involve genetic abnormalities that carry the name of primary mutations. Some of these mutations are responsible for triggering the disease, while others are responsible for sustaining its progression.

A very common subtype of lymphoma is follicular lymphoma. This variety of lymphoma is slow progressing and alternates between periods of remission and periods of relapse. In the majority of cases, follicular lymphoma is caused by a specific genetic mutation that affects the B lymphocytes. The mutation causes an overproduction of the BCL2 protein, a type of protein that stimulates an excessive accumulation of B cells, which begin to act like cancerous cells.

Another common subtype of Non-Hodgkin's Lymphoma is diffuse large cell lymphoma. This variety progresses faster and it can also originate from a slower progressing lymphoma subtype. Diffuse cell lymphoma requires immediate treatment; otherwise, the disease can become life-threatening in a very short amount of time. The most efficient form of treatment consists in chemotherapy. Although most patients with diffuse cell lymphoma experience relapse, a second course of strong chemotherapy is usually effective in curing relapsed cases.

Burkitt's lymphoma is a rapidly evolving lymphoma subtype that occurs due to a unique genetic anomaly. This variety of lymphoma requires immediate medical intervention and involves a poor patient life expectancy. When chemotherapy is not sufficient for treating patients with Burkitt's lymphoma, combination treatments with immunosupressants can help ameliorate its symptoms and slow its progression rate.

Unlike B-cell lymphomas, T-cell lymphomas are rare and account for about 20 percent of cases of all Non-Hodgkin's Lymphoma in general. T-cell lymphomas are rapidly progressing and often involve the body skin. Along with Hodgkin's Disease, T-cell lymphoma raises serious issues in diagnosis and treatment. This is due to the poor understanding of the causes and evolution of the disease, medical scientists lacking conclusive medical data. However, medical scientists hope to unveil the exact origins and the pattern of evolution characteristic to Non-Hodgkin's T-cell lymphoma and Hodgkin's Disease in order to develop an efficient treatment in the near future.