Clinical and Biological Features of Biclonal Gammopathies. Review of 203 Cases

Introduction: Biclonal gammopathies represent about 5% of clonal gammopathies. We describe the clinical and laboratory features of biclonal gammopathies identified in a French university hospital.

Methods: Patients were selected by immunofixation registry of Biochemistry laboratory.

Results: From 1987 to 2008, 203 biclonal gammapathies were identified. Patients were 113 men and 90 women. Median age was 72.0 years (35–95). Seventy eight patients (38.3%) had IgG and IgM components, 64 (31,9%) had two IgG, 24 (11,8%) had IgG and IgA, 23 (11,3%) had two IgM, 8 (3,9%) had IgM and IgA, 5 (2,4%) had two IgA, one (0.5%) had Ig G and IgD (0,5%). Of the 406 light chains, 260 (63,8%) were kappa, 146 (36.2%) were lambda. Eighty nine patients (44.1%) had two kappa light chains, 82 (40,2%) had both kappa and lambda and 32 (15,7%) had two lambda chains. Median gammaglobulin concentration was 13.3 g/L (3–59.9). The most frequent diagnosis was biclonal gammopathy of undeterminated significance (BGUS) in 123 patients (60.6%). Others patients could be divided into 3 groups. Forty seven patients (23.1%) had lymphoproliferative diseases, including Waldenström’s macroglobulinemia (21 cases), non Hodgkin lymphoma (20), chronic lymphocytic leukaemia (6). Eighteen (8.87%) had multiple myeloma. For the last 15 patients (7.4%), biclonal gammopathy was associated with a non lymphoid hemopathy or with systemic disease. Biclonal gammopathy was identified in 12 patients already known to have a monoclonal gammopathy (7 monoclonal gammopathy of undetermined significance-MGUS, 3 myeloma and 2 Waldenström’s macroglobulinemia). In 3 cases, the finding of the second monoclonal component was concurrent to the diagnosis of a MGUS malignant transformation to myeloma (2 cases) or Waldenström’s macroglobulinemia (1 case). Median follow-up was 23 months (12 to 252 months) for the 123 patients with BGUS. In 4 cases (3.2%) a malignant transformation was observed. Three patients developed a multiple myeloma (time to transformation was 2 years for one and 4 years for the 2 others) and one patient Waldenström’s macroglobulinemia (6 years).

Conclusions: As for monoclonal gammopathies, BGUS represent the most frequent diagnosis. However, in contrast to monoclonal gammopathies, biclonal gammopathies are more frequently associated with lymphoproliferative diseases than with multiple myeloma. The apparition of a second monoclonal component during follow up of MGUS could be associated with malignant transformation and should lead to new evaluation. The risk of transformation of BGUS seems similar to MGUS but further studies are necessary to compare the evolution of MGUS and BGUS.