[Secondary monoclonal gammopathy after bone marrow autotransplantation as a cause of worse renal function in light chain immunoglobulin deposition disease].

The paper describes a clinical case of a female woman with nephropathy due to light chain deposition disease caused by secretion of κ Bence-Jones protein. Complete immunochemical remission was achieved after induction therapy using a bortezomib + cyclophosphamide + dexamethasone regimen. Renal function remained unchanged (glomerular filtration rate 16 ml/min), there was a reduction in proteinuria from 5.8 to 2.6 g/day. High-dose melphalan (200 mg/m2) chemotherapy with peripheral blood stem cell autotransplantation was performed as consolidation of remission. A year posttransplantation, there was no secretion of κ light chains; however, monoclonal IgG lambda emerged in a quantity of 3.2 g/l. At the same period, nephrotic syndrome became progressive (daily proteinuria 12 g) and dialysis-dependent renal failure developed. A repeat renal biopsy specimen revealed changes, suggesting that there was a decrease in renal deposits of κ light chains. Simultaneously with this, the obvious negative trend as progressive nephrosclerosis and fixation of IgG and λ light chains in the glomeruli (in the sclerotic areas) cause IgGλ monoclonal protein to be involved in the genesis of further kidney injury. Attention is also paid to different characteristics of capillary wall deposits by density (according to the electron microscopic findings), which may point to their different qualitative composition and possibly different formation duration. Papaprotein Gλ disappeared after a year without therapy, suggesting its reactivity. The findings confirm that worse renal function is caused by the action of paraprotein Gλ due to secondary (after autologous hematopoietic stem cells transplantation) monoclonal gammopathy.