Rapidly Progressive Renal Failure in AA Amyloidosis: A New Clinical and Histopathological Entity for an Old Disease

Abstract

Objective: Secondary renal AA amyloidosis (RAAA) presents with proteinuria and/or as nephrotic syndrome and progresses to end stage renal disease (ESRD) insidiously. However, some patients with secondary amyloidosis show a more rapid renal disease progression than the usual course. In this study, we aimed to investigate the underlying cause of the rapidly progressive renal disease in the patients with secondary amyloidosis.

Materials and Methods: Patients with kidney biopsy proven secondary RAAA were divided into 2 groups: the rapidly progressive group (estimated glomerular filtration rate >60 mL/min, who needed renal replacement therapy within one year of diagnosis) and the control group. Biopsy specimens were reevaluated for glomerular-vascular amyloid load, tubular atrophy, interstitial fibrosis, and interstitial inflammation. The biopsy characteristics and biochemical parameters were compared between the groups.

Results: Histopathological examination showed global amyloid deposition, vascular pole involvement, peritubular capillary amyloid deposition, and severe interstitial inflammation associated with rapidly progressive disease. Estimated glomerular filtration rate was lower and proteinuria was higher in the rapidly progressive group than in the control group. Vascular pole amyloid deposition was found to be a predictor of ESRD in multivariate analysis.

Conclusion: This study shows that higher amyloid deposition and severe inflammation revealed in in kidney biopsy of secondary RAAA cases can be risk factors for rapidly progressive renal failure.