Development of nodular lesions in amyloidosis with reference to diabetic nephropathy

Abstract

Background: One characteristic histologic change in diabetic glomerulopathy is nodular and diffuse mesangial expansion, which resembles the alterations seen in renal amyloidosis. We addressed the questions of whether the morphologic changes seen in renal amyloidosis are related to the biochemical amyloid type, and whether there is a histologic analogy in diabetic glomerulopathy. Methods: We examined kidney specimens obtained from autopsies on 30 patients with systemic amyloidosis and 34 with diabetes mellitus. Results: The mean age at death of the patients with amyloidosis was 60.6 + 10.9 years. All samples were positively stained by Congo red and direct fast scarlet stains. All nonnephrotic patients showed minimal diffuse or nodular lesions. Most of the lesions found in the patients with nephrosis were severe. We also assessed the histologic glomerular changes in 34 cases of diabetes mellitus. The mean age at death of the patients in this group was 62.3 _+ 12.3 years. In diabetic nephropathy, severe nodular lesions did not appear until there was progression of diffuse lesions. By contrast, in the amyloid kidney, nodular mesangial expansion could be seen in glomeruli even when the diffuse mesangial expansion was slight. Conclusions" There is no significant relationship between histologic amyloid deposition patterns and biochemical amyloid types. Although, in both diabetic nephropathy and renal amyloidosis, the histologic alterations of the kidneys include diffuse and nodular mesangial expansion, these alterations progress separately in amyloidosis, while in diabetic nephropathy, the nodular lesions appear after progression of diffuse mesangial thickening.