Non-Hodgkin's Lymphoma - Introduction

Introduction

Lymphomas are malignancies of the lymph system that are generally subdivided into two groups, Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL). Hodgkin's disease accounts for about 15% of all lymphomas. [For more information, see In-Depth Report #83: Hodgkin's disease.]

Non-Hodgkin's lymphoma is a term for malignancies that range from a very slow disease to an extremely aggressive but curable condition. They have certain features in common.

---

---

The Lymphatic System

Lymphomas, such as non-Hodgkin's lymphomas and Hodgkin's disease, represent tumors of the lymphatic system. This system is a network of organs, ducts, and nodes. The lymphatic system interacts with the blood's circulatory system to transport a watery clear fluid called lymph throughout the body. The lymphatic system contains lymphocytes, important cells involved in defending the body against infectious organisms.

Lymphocytes. The lymphatic system is involved in the production and transportation of lymphocytes, white blood cells that are a primary component of the immune system.

• Lymphocytes develop in the bone marrow or thymus gland and are therefore categorized as either B cells (bone marrow-derived cells) or T cells (thymus gland-derived cells).
• Lymphatic vessels begin as tiny tubes and lead to larger lymphatic ducts and branches until they drain into two ducts in the neck, where the fluid re-enters the bloodstream.
• Along the way, the fluid passes through lymph nodes, oval structures composed of lymph vessels, connective tissue, and white blood cells. Here, the lymphocytes are either filtered out or added to the contents of the node.
• Both leukemia and lymphomas (Hodgkin’s disease and non-Hodgkin’s lymphomas) are cancers of lymphocytes. The difference is that leukemia starts in the bone marrow while lymphomas originate in lymph nodes and then spread to the bone marrow or other organs.