IgA kappa light and heavy chain deposition disease in multiple myeloma.

Abstract

A 46-year-old patient was referred to our unit with acute renal failure, his serum creatinine having risen from 137 to 431 μmol/l in eight months. He was born in the Republic of the Congo and had lived in France since 2009. He had no significant previous medical history. On admission, clinical examination was normal except for high blood pressure. Blood analyses confirmed renal impairment. Urine analyses were significant for proteinuria (urinary protein to creatinine ratio 1 g/g), haematuria (105 red cells/ml) and leucocyturia (104 white cells/ml). Serum protein electrophoresis revealed an M-spike and urine protein electrophoresis showed light-chain proteinuria. The paraprotein was identified by immunofixation as immunoglobulin (Ig) A kappa. Bone marrow examination showed 28% clonal plasma cells. Kidney biopsy revealed Congo red-negative thickening of glomerular capillary walls and tubular basement membranes, with peritubular multinucleated giant cells (top left). Electron microscopy showed granular electron-dense material along the lamina rara interna of the glomerular capillary walls and along the outer aspect of the tubular basement membranes (top right). Immunofluorescence confirmed the diagnosis of light and heavy chain deposition disease (LHCDD) by demonstrating staining for IgA heavy chain (bottom left) and kappa light chain (bottom right), without staining for lambda light chain. Haemodialysis was initiated and the patient received first line chemotherapy with bortezomib, cyclophosphamide and dexamethasone. Eight months later, he exhibited an excellent partial haematological response. However, his renal function did not improve and he still required dialysis. Light and heavy chain deposition disease is a very uncommon subtype of monoclonal immunoglobulin deposition disease and only small numbers of cases of IgA kappa LHCDD have been reported. The authors thank the HUPNVS of Assistance Publique - Hôpitaux de Paris for funding publication fees.