Abstract
Malignant lymphomas have traditionally been classified on solely morphological grounds. With new immunological and cytochemical techniques, it has been possible to characterize normal cells of the T-lymphocyte, B-lymphocyte, and monocyte-macrophage system. Application of these methodologies to malignant lymphomas has established their nature as neoplasms of the immune system. Within the B-lymphocyte system it is possible to identify subpopulations responsible for Burkitt's tumour, follicular (nodular) lymphomas, lymphocytic lymphomas of intermediate differentiation and well differentiated lymphocytic lymphomas. The T-lymphocyte system includes lymphoblastic lymphomas, mycosis fungoides, and Sezary's syndrome. Large-cell lymphomas are diverse, but the majority are tumours of transformed lymphocytes, usually of the B-lymphocyte 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-lymphocyte or T-lymphocyte origin, recent studies with in vitro cultivation have strongly suggested derivation from the monocyte-macrophage system.