A case of monoclonal immunoglobulin light- and heavy-chain deposition disease exhibiting atypical deposition with fibrillary structures, successfully treated with chemotherapy.

We report a case of light and heavy chain deposition disease (LHCDD), a rather rare monoclonal immunoglobulin deposition disease (MIDD) with successful therapeutic effect. A 58-year-old woman suffered from proteinuria and renal insufficiency (serum creatinine 1.0 mg/dl, creatinine clearance 49.2 ml/min) in February 2003. In serum and urine samples, monoclonal IgG-kappa was detected. A bone marrow aspiration showed a slightly hypocellular marrow and plasma cell population was increased to 7.0%. Renal histological findings revealed lobulated glomeruli with nodular lesions on light microscopy, characteristic findings of MIDD. Intense deposition of IgG heavy chains in the linear pattern in the glomerular and tubular basement membranes was observed. Immunohistochemistry revealed both kappa and lambda light chain depositions in glomeruli. Electron-microscopic examination revealed fine granular electron-dense deposits accompanied by microfibrils. Based on these findings, this patient was diagnosed as LHCDD. She received three courses of melphalan and prednisone chemotherapy, resulting in disappearance of proteinuria, prevention of renal functional deterioration and the decrease of monoclonal immunoglobulin. This case clearly demonstrates that the earlier and accurate diagnosis and initiation of chemotherapy at the early stage with serum creatinine level below 4.0 mg/dl are necessary to improve renal and patient outcome.