The clinical significance of antigen receptor gene rearrangements in lymphoid neoplasia

Lymphoid neoplasms include Hodgkin disease, non-Hodgkin lymphomas, various forms of lymphocytic leukemias, and multiple myeloma.Excluding Hodgkin disease, most of these neoplasms represent lymphoproliferative disorders derived from lymphocytes, their precursors, and their descendants.Diagnosis of these disorders is often difficult compared with other cancers and cancer-like conditions.Cytologically malignant lymphocytes may resemble activated reactive lymphocytes or normal resting ones.In addition, reactive lymphocytes may be admixed with the neoplastic population and obscure its presence.Even in acute lymphoblastic leukemia, when circulating blasts and a "packed' marrow simplify the primary diagnosis, iden- tification of early postchemotherapeutic relapses in bone marrow, peripheral blood, or other sites frequently is a difficult diagnostic problem.Immunologic analyses of cellular antigens have contributed significantly to an improved diagnosis of lymphoid neoplasms.These tests indicate patterns of antigenic expression by lymphocytes in biopsy specimens that correlate with the presence of a neoplasm or a reactive process in the specimen.The most widely used analysis of this sort is the detection of cellular kappa or lambda immunoglobulin light chains.An individual lymphocyte expresses an immunoglobulin consisting of two identical heavy chain subunits and two identical light chain subunits, which may be of either the kappa or lambda type.Detection of cellular immunoglobulin restricted to one or the other light chain type