SUN-422 MONOCLONAL IGA NEPHROPATHY WITH LATTICE LIKE PARA-CRYSTALLINE DEPOSITS IN AN ELECTRON MICROSCOPY: A RARE FINDING

Abstract

Abnormal plasma cells frequently cause the secretion of monoclonal immunoglobulins or immunoglobulin fragments into the serum which leads to various diseases including renal diseases. When patients do not meet the criteria for overt multiple myeloma/B-cell proliferation, and the hematologic disorder is generally consistent with monoclonal gammopathy of undetermined significance (MGUS) but renal abnormalities are consistent, it is called monoclonal gammopathy of renal significance (MGRS). It is associated with high morbidity so early recognition is important, as chemotherapy invariably improves outcomes. Proliferative glomerulonephritis secondary to monoclonal IgA has been previously described on single occasional only and electron microscopy finding is quite unique, with mesangial and subendothelial deposition of lattice-like para crystalline arrays. This is a case report. Case details: A 46-year-old male patient with proteinuria and hematuria for 20 months presented to the nephrology outpatient department. His protein was 3+ and hemoglobin was 2+ in urine. All of the serologies were negative. Renal biopsy was done, which showed mild increase in mesangial matrix with slight accentuation of lobulation, double contours on silver and PAS stains. There were no glomeruli in the original frozen material for immunofluorescence studies; therefore, immunofluorescence was carried out on paraffin sections which showed moderate mesangial IgA staining and mild mesangial lambda staining. Rest of the stains were negative in glomeruli. IgG, IgA, IgM, C3, C1q, kappa, lambda and albumin were used as a panel for immunofluorescence. Electron microscopy showed numerous electron-dense para crystalline deposits in mesangial and subendothelial locations with highly distinctive organized substructure forming lattice-like para crystalline arrays with a periodicity of 18 nm which were slightly curved in some areas. Proliferative glomerulonephritis with monoclonal gammopathy has been reported few times but most of these deposits were granular and rarely fibrillary deposits were present. Among of the cases of renal disease due to monoclonal gammopathy, IgG was the most common immunoglobulin that was deposited, followed by IgM. Renal disorder secondary to a monoclonal IgA lambda is very rare. Deposition of lattice like paracrystalline substructure with parallel arrays in a “blocky” pattern is a unique finding in proliferative glomerulonephritis due to monoclonal lambda restricted IgA nephropathy, which was only reported by Soares et al before this case. Such electron microscopy picture is very rare and unique, and diagnostic for the disease.