Essential monoclonal gammopathy is defined by two key features: (a) the presence of a monoclonal immunoglobulin (Ig) or a monoclonal Ig light chain in the serum and (b) the absence of evidence for an overt malignancy of B lymphocytes or plasma cells (eg, lymphoma, myeloma, or amyloidosis). The prevalence of essential monoclonal gammopathy depends on the demographic features in the population under study. In Americans of European descent, the prevalence increases from approximately 2% in individuals 50 years of age to approximately 7% in octogenarians. It is two to three times as prevalent in persons of African descent. The condition has been reported in association with a large variety of disorders, especially nonlymphocytic cancers. These coincidences are thought, in most cases, to be the chance concurrence of conditions that have a high prevalence in older persons. Some cases of essential monoclonal gammopathy are symptomatic because in these cases, the Ig can interact with plasma proteins, blood cells, kidney, ocular structures, or neural tissue and cause serious dysfunction, for example, an acquired bleeding disorder, renal insufficiency, or an incapacitating neuropathy. In such cases, disability may be so great that attempts to remove the Ig by plasmapheresis and to suppress its production using immune or cytotoxic therapy can be warranted. Because myeloma or lymphoma may emerge soon after the monoclonal Ig is first detected, subsequent evaluation of the patient is required to ascertain if essential monoclonal gammopathy is the appropriate diagnosis. Long-term follow-up at appropriate intervals is prudent to detect conversion from a stable, asymptomatic condition to a progressive lymphoma or myeloma, which occurs in approximately 0.75% of cases per year. In the absence of a symptomatic monoclonal gammopathy (eg, renal or neurologic involvement) or evolution to a progressive clonal gammopathy, periodic follow-up of patients is all that is required.
Acronyms and Abbreviations
Acquired immunodeficiency syndrome, AIDS; CD, cluster of differentiation; HLA, human leukocyte antigen; Ig, immunoglobulin; IL, interleukin; paratarg-7, P-7; MGUS, monoclonal gammopathy of unknown significance; MGIP, monoclonal gammopathy of indeterinant progression.
The syndrome of essential monoclonal gammopathy has two important characteristics. The first feature is a plasma immunoglobulin (Ig) or Ig light chain that has the molecular features of the product of a single clone of B lymphocytes or plasma cells: homogeneous electrophoretic migration and a single Ig light-chain type. The second feature is the absence of evidence of an overt neoplastic disorder of B lymphocytes or plasma cells, such as lymphoma, macroglobulinemia, myeloma, or amyloidosis.
The observations that Bence Jones proteinuria could precede the clinical signs of multiple myeloma by many years1 and that hyperglobulinemia without evidence of multiple myeloma could occur in some patients2 antedated the concept of monoclonal gammopathy as a syndrome. With the more frequent clinical application of zonal electrophoresis of plasma proteins during the 1950s and 1960s, patients were discovered who had a monoclonal Ig, either ...