What is the lymph system, and what are lymph nodes? The lymph system is essentially the "housekeeping system" of the body. It is a network of vessels (tubes), which connect the lymph nodes. These nodes can vary in size, but are normally up to about 2 centimeters in width. They contain cells that clear bacteria and other foreign debris from the body. Lymph is a watery liquid that flows between cells in the body, picking up foreign debris and taking it into the lymph node for filtering. From the lymph node, the debris may pass through several more nodes in the system before being dumped into the bloodstream to ultimately be cleared by the liver. The lymph system flows throughout the body, and also includes the spleen and thymus gland. What is a lymphocyte? Lymphocytes are a type of white blood cell. These cells (called B cells and T cells) are important in fighting infection and ... read more on Non-Hodgkin's Lymphomas: The Basics

What is lymphoma? In general, lymphoma is a type of cancer affecting cells of the lymph system. The lymph system is part of the immune system that consists of a network of lymph nodes, lymph vessels, and organs, including the thymus, spleen, and bone marrow. Lymphoma can arise from any of these tissues. There are two broad categories of lymphoma: non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma, which is discussed in a separate article. The cancerous cell in NHL is called a "lymphocyte", which is a cell that ordinarily is involved in the immune response that protects the body from infection. In NHL, these lymphocytes divide at an abnormally fast rate causing enlargement of lymph nodes or other organs in the lymph system and are responsible for the symptoms experienced by children with NHL. Who is at risk for NHL? As for most childhood cancers, the majority of pediatric ... read more on Non-Hodgkin Lymphoma (Pediatric): The Basics