Nodular lymphomas: current concepts.

The past several years have witnessed innovative approaches to clinical management as well as significant insights into the basic biology of the nodular lymphomas. Clinical studies have explored two apparently widely disparate approaches to the treatment of patients with nodular lymphoma. On the one hand, withholding initial therapy (watch and wait) has proved to be a viable option in the management of some patients. This approach has provided information regarding the natural history of disease, such as the relative incidence of spontaneous tumor regression vs. histologic transformation to more aggressive forms of lymphoma. Alternatively, recent data also suggest that the administration of intensive chemotherapy, shown to induce long-term remissions in a high percentage of patients with diffuse aggressive lymphomas, may also produce a significant number of durable remissions in at least certain histologic subtypes of nodular lymphomas. Clinical studies which attempt to achieve a synthesis of the above two approaches are currently in progress. Advances in immunology and molecular biology have also found application in the study of nodular lymphoma. Monoclonal antibodies have been employed diagnostically, as, for example, in detecting small numbers of persistent abnormal lymphoid clones in patients in apparent remission, and therapeutically, as exemplified by the clinical use in vivo of monoclonal antibodies directed against unique idiotypic determinants expressed by surface immunoglobulin on the malignant B lymphocytes. The demonstration of the immunoglobulin gene rearrangements in nodular lymphoma cells has established a more definitive criterion for their phenotypic characterization. Finally, molecular cloning of the breakpoint of the t(14; 18) chromosome translocation frequently found in nodular lymphoma cells has led to the identification of a potential new transforming gene which could be activated as a direct consequence of its rearrangement in proximity to the immunoglobulin in heavy chain gene locus.