A data base for 3000 monoclonal immunoglobulin cases and a new classification.

Data from monoclonal immunoglobulin cases screened in our laboratory for 40 years were used to assemble a cohort of 3094 cases selected according to immunoelectrophoresis and immunofixation interpretation and clinical data availability. Molecular distribution and original classification were used to establish five categories of cases: multiple myeloma (MM) and Waldenstrom macroglobulinemia (WM), other lymphoproliferative diseases, cases associated with heavy immunological diseases or other tumors, and benign cases. Free light chain (FLC) cases comprise 7% of the cohort, pluriclonal Ig, 6%. More than 50% of 1335 cases with identified diagnoses are not malignant hemopathies. Male/female ratio is less than 1 for MM cases and close to 1 for benign and other lymphoproliferative cases. Males are a majority in MW and associated cases. Follow-up periods range from 5 to 30 years for 263 cases. The main characteristics of this data base have been defined and the benefit of the original classification is highlighted. Future studies will investigate improvements resulting from immunofixation and current urinary analysis practices, as well as long-term follow-up, pluriclonal Ig cases, cryoglobulins, the meaning of the presence of FLC and malignant transformation.