Renal Amyloidosis (AL Kappa Type) With an Uncommon Presentation: A Case Report

Abstract

Amyloidosis is a disease associated with deposits of amyloid fibrils that aggregate in various tissues leading to progressive organ failure and often multi-systemic involvement. It may be classified as localized or systemic, acquired or hereditary. Renal presentation is variable but can include nephrotic syndrome, acute renal failure, tubular dysfunction, or just varying degrees of proteinuria. Although most cases of renal amyloidosis are due to acquired causes, in rare instances, the cause can be gene mutations leading to hereditary amyloidosis. We present the case of a 77-year-old Caucasian man diagnosed with renal biopsy-proven AL (kappa) type amyloidosis with isolated renal involvement who had a significant family history of renal biopsy-proven amyloidosis.

Keywords: al amyloidosis; case report; clinical presentation; hereditary; renal.

Figure 1. Arteriosclerosis of interlobular arteries and arterioles in renal biopsy (Masson's trichrome stain).

Arteriosclerosis of interlobular arteries and arterioles as demonstrated with green arrows.

Figure 2. Pale amorphous and acellular material (amyloid) within glomeruli in renal biopsy (periodic acid-silver methenamine stain).

Pale amorphous material (amyloid) within glomeruli as demonstrated with green arrow.

Figure 3. Pale amorphous material and acellular material (amyloid) within glomeruli and interstitium as shown by the green arrow (periodic acid-Schiff stain).

Figure 4. Congo red-positive material, which was apple-green under polarized light as demonstrated by green arrows (Congo red stain).

Figure 5. Mesangial expansion by the presence of numerous, thin, randomly oriented fibrils (green arrows) that frequently extend along the paramesangial regions and capillary loops. There is severe epithelial foot process effacement (transmission electron microscopy - magnification x200 in A-C x40,000 in D).