Monoclonal gammopathy of undetermined significance

Introduction.-Monoclonal gammopathy of undetermined significance is an asym ptomatic disorder associated with serum monoclonal immunoglobulin spike. It s incidence is about 1% in patients of 50 years of age, and rapidly increas es in elderly patients. Current knowledge and key points. - Within the 20 years following diagnosis , about 25% of patients will evolve towards either multiple myeloma (for pa tients with IgG or Ig A) or malignant lymphoproliferative disorder (for pat ients with IgM). Definition, circumstances associated with a transient mono clonal spike, and currently available parameters used for differential diag nosis with either multiple myeloma or malignant lymphoproliferative disorde r are successively discussed. One part of the most usual biological paramet ers is of prognostic value, and is reviewed in more detail. Recent data con cerning immunophenotype, cytogenetics and molecular biology of plasma cells reinforce the link between the asymptomatic condition and multiple myeloma . In monoclonal gammopathy of undetermined significance, some plasma cells resemble normal or reactive plasma cells, whereas others mimic those found in multiple myeloma. Future prospects and projects.-The most recent biological data are also dis cussed in order to evaluate whether some would help to discriminate those p atients who will remain asymptomatic lifelong from those who will evolve to wards multiple myeloma. (C) 2000 Editions scientifiques et medicales Elsevi er SAS.