PS-BPR03-1: DIAGNOSIS OF MONOCLONAL IMMUNOTACTOID GLOMERULOPATHY WITH POSITIVE LAMBDA CHAIN BY IMMUNOELECTRON MICROSCOPY

Abstract

We report a case of a 73 year old man who developed immunotactoid glomerulopathy (ITG). ITG is a rare disease characterized by proliferative glomerulonephritis and capillary wall deposits with a 10 to 60 nm diameter microtubular substructure. Recent reviews recommend distinguishing monoclonal ITG from polyclonal ITG because monoclonal ITG is associated with a higher incidence of hematological disorders and better responsiveness to clone-directed therapy and renal prognosis. In monoclonal ITG, immunofluorescence analysis typically exhibits IgG with light chain restriction, most often kappa chain restriction. This is the first reported case of a monoclonal ITG, positive only for the lambda chain detected by immunoelectron microscopy. At 6 months after his renal biopsy, the IgG lambda chain was detected in the serum and urine, reflecting possible monoclonality. We would like to present the usefulness of immunoelectron microscopy using biopsy samples as well as protein electrophoresis/ immunofixation using serum and urine samples to diagnose monoclonal ITG, even when routine immunofluorescence shows negative or nonspecific findings. Conclusions: It is important to distinguish monoclonal ITG from polyclonal ITG. Immunoelectron microscopy is useful as a salvage technique to diagnose monoclonal ITG.