Gene rearrangements in malignant lymphomas

The use of molecular methods to diagnose malignant lymphoma, while firmly established in reference centers, has not been well evaluated at the community level. A group of 57 specimens from patients with non-Hodgkin's lymphomas (NHL), lymphoid leukemias (LL), and a variety of other lymphoproliferative lesions with the Southern blot methodology have been studied by us. Molecular probes to the joining regions of the heavy (JH) and light (J kappa) immunoglobulin chains and the beta (J beta 1-2) chain of the T cell receptor genes were used. Gene rearrangements were detected in 90 percent of all NHL/LL with a 95 percent detection rate specifically for B-NHL/LL. In comparison, phenotypic analysis by immunoperoxidase stains favored a B phenotype in 75 percent of those cases, while flow cytometry assigned 63 percent of cases to a B cell lineage. Gene rearrangements were detected in four of six cases of T-NHL for a rate of 67 percent. The six other lymphoproliferative lesions included Hodgkin's disease, Castleman's disease, and a case of lymphoid hyperplasia. No rearrangements were detected in these specimens. The studies allowed development of increased confidence in the diagnosis of NHL/LL on ever smaller specimens. The availability of these studies has also helped establish a priority of handling all specimens so that the most appropriate studies can be performed to yield the most useful diagnostic information.