Classification of non-Hodgkin's lymphomas: facts and perspectives]

Previous classifications of malignant non-Hodgkin lymphomas (nHL) are based on morphological and histological-cytological findings. The rapid development of immunology, the application of immunocytological, cytochemical and electromicroscopic methods led to new classifications of nHL based on immunology. They are founded on the idea that the prevailing cells of nHL correspond to a cell type from the differentiation line of lymphocytes. Thus, a distinction can be made between malignant lymphomas (ml) of stem, B and T-cells; the more frequently occurring lymphomas originating from B-cells are represented by chronic lymphatic leukaemia originating from B1-cells, by ml of follicular genesis (centrocytes, centroblastic-centrocytic ml, centroblasts) and by ml synthesizing and releasing immunoglobulins (immunocytoma, immunoblastoma). The type formerly called "reticulosarcoma" (histocytic ml) could be identified to be an immature, Ig synthesizing ml (immunoblastloma) in most cases. The new classification enables a more extensive differentiation and a better prognostic statement to be made than previous ones. The new units of disease can be diagnosed in most cases with light microscopic routine methods, although borderline cases and unclassifiable ml may occur.