non-Hodgkin's lymphoma any cancer of the lymphoid tissue (see lymphatic system ) in which the Reed-Sternberg cells characteristic of Hodgkin's disease (the other category of lymphoma) are not present. There are about 10 different types of non-Hodgkin's lymphomas, some slower- or faster-growing than others. Non-Hodgkin's lymphoma can affect children as well as adults. In most cases the cause is unknown, but an increased incidence has been observed in people who have been exposed to Agent Orange , and some forms of the disease are frequently seen in people with AIDS , many of these in association with latent Epstein-Barr virus infection. Symptoms The first symptom of non-Hodgkin's lymphoma is often a painless swelling of a lymph node in the neck, the groin, or under the arm. Other symptoms include fever, night sweats, itching, and unexplained weight loss. Diagnosis is made by laboratory study of tissue obtained by taking a biopsy of the suspicious lymph node or nodes. Treatment Treatment depends on how far the disease has progressed. It may include external-beam radiation therapy, chemotherapy, or biological therapy (boosting the body's immune response to the disease). Rituxan, a genetically engineered drug involving monoclonal antibodies , has been approved for use against some low-grade (slow-growing) non-Hodgkin's lymphoma. Bone marrow transplantation is also sometimes used. In this technique, bone marrow (blood cell-producing tissue inside bone) is taken from...