Summary

Light chain deposition disease (LCDD) and immunoglobulin light chain (AL) amyloidosis are uncommon, and heterogeneous clonal plasma cell (PC) proliferative disorders defined by the different biochemical characteristics of the underlying anomalous immunoglobulin. The deposits are usually multisystemic and the two diseases can coexist. The diagnosis is sometimes made difficult by the absence of a detectable paraprotein by routine immunofixation techniques, and the use of serum-free light chain (FLC) immunoassay brought new value in terms of their diagnosis, prognosis and assessment of treatment response. Association of LCDD and AL amyloidosis with multiple myeloma (MM) at the time of diagnosis is common, but further progression to this condition is considered rare. We present a case of a patient diagnosed with systemic LCDD and AL amyloidosis of atypical biochemical characteristics, with no paraprotein detected in immunoelectrophoresis and immunofixation techniques, who progressed to MM in the later course of her disease.