[Ultrastructural and immunoelectron microscopic study on light chain deposition diseases and primary amyloidosis of the kidney].

OBJECTIVE

To investigate the role of electron microscopy (EM) and immunoelectron microscopy (IEM) in the diagnosis of light chain deposition diseases (LCDD) and primary amyloidosis (AL) of the kidney. METHODS Renal biopsy specimens collected in our hospital from Jan. 1994 to Feb. 2002 were studied by EM, and ultrastructural immunogold labeling for light chains (kappa, Lambda) were made on the cases suggested of LCDD and early stage AL in the preliminary diagnosis.

RESULTS

Six cases were diagnosed as LCDD, and punctate, granular, electron-dense material was identified in the outside of tubular basement membrane (TBM), inner layer of glomerular basement membrane (GBM) and vascular walls by EM. Two of which showed interrupted segmental localization of granular material in subendothelial areas of GBM. The granular material was labeled by monotypical light chains (4 cases of kappa chain, 2 cases of Lambda chain). Thirty-six cases were diagnosed as AL. EM revealed fibrillary material distributed in glomerular mesangium, GBM and vascular walls; 15 of them showed segmental distribution of fibrils in mesangium and/or GBM, and were further studied by IEM labeling for light chains. The fibrillary material was labeled by monotypical light chains (4 cases of kappa chain, 11 cases of Lambda chain). CONCLUSION The diagnosis of renal LCDD and early stage of AL depended on EM, IEM is a unique diagnostic tool in early stage of LCDD and AL.