MSH: A general term for various neoplastic diseases of the lymphoid tissue.,CSP: malignant (clonal) proliferation of B- or T- lymphocytes which involves the lymph nodes, bone marrow and/or extranodal sites; general term for various neoplastic diseases of the lymphoid tissue.,NCI: Cancer that begins in cells of the immune system. There are two basic categories of lymphomas. One kind is Hodgkin lymphoma, which is marked by the presence of a type of cell called the Reed-Sternberg cell. The other category is non-Hodgkin lymphomas, which includes a large, diverse group of cancers of immune system cells. Non-Hodgkin lymphomas can be further divided into cancers that have an indolent (slow-growing) course and those that have an aggressive (fast-growing) course. These subtypes behave and respond to treatment differently. Both Hodgkin and non-Hodgkin lymphomas can occur in children and adults, and prognosis and treatment depend on the stage and the type of cancer.,MEDLINEPLUS: Lymphoma is a cancer of a part of the