AH Amyloidosis Treated with Rituximab

Introduction: Heavy chain amyloidosis is a rare type of amyloidosis caused by deposition of monoclonal immunoglobulin heavy chain usually produced by clonal plasma cells. Here we report a case of renal AH amyloidosis caused by clonal B lymphocytes and showed good prognosis after Rituximab treatment. Case Description: A 67-year-old woman presented with nephrotic syndrome and progressively renal insufficiency was admitted. Laboratory results revealed sCr 303μmol/L, proteinuria 4.6 g/d, serum albumin 27g/L, and pancytopenia. Elevated κ/λ ratio 5.3, IgG κ monoclonal protein were detected. Anti-aCL IgM, aβ2GPI and anti-platelet were strongly positive. Bone marrow biopsy showed 0.2% abnormally mature small B lymphocytes and 0.1% plasma cells expressing κ light chain restriction. Kidney biopsy (figure 1) showed weakly PAS-positive nodules in glomeruli, with bright mesangial and capillary wall staining for IgG by IF and fibrillary deposits under EM. However, Congo red was negative. Laser microdissection/mass spectrometry studies confimed the AH (IgG) amyloidosis by detecting large signature amyloid spectra of IgG1, apo E, and A-IV. Therefore, renal AH amyloidosis was diagnosed. The patient was given rituximab, and kidney function improved with decreased urinary protein (figure 2). Discussion: LMD/MS analysis is crucial in the diagnosis of rare amyloidosis. The choice of treatment should consider affected organs and the source of malignant cells. The prognosis is relatively good after appropriate therapy.