Immunologic aspects and pathology of the malignant lymphomas.

Malignant lymphomas have traditionally been classified on solely morphologic grounds. With new immunologic and cytochemical techniques, it has been possible to characterize normal cells of the T-lymphocytic, B-lymphocytic, and monocyte-macrophage systems. Application of these methodologies to malignant lymphomas has established their nature as neoplasmas of the immune system. Within the B-lymphocytic system it is possible to identify subpopulations responsible for Burkitt's tumor, follicular (nodular) lymphomas, lymphocytic lymphomas of intermediate differentiation and well differentiated lymphocytic lymphomas. The T-lymphocytic system includes lymphoblastic lymphomas, mycosis fungoides, and Sezary's syndrome. Large cell lymphomas are diverse but the majority are tumors of transformed lymphocytes, usually of the B-lymphocytic system. The precise nature of the neoplastic cells of Hodgkin's disease, i.e., Reed-Sternberg cells and their mononuclear counterparts, has not yet been established. Despite previous suggestions of a B-lymphocytic or T-lymphocytic origin, recent studies utilizing in vivo cultivation have strongly suggested derivation from the monocyte-macrophage system.