Diagnosis: Amyloidosis
• Fibrillary deposits of amyloid are randomly arranged, are nonbranching, and measure 9 to 12 nm in diameter (see inset of image).
• Identical fibrillary deposits are found in all affected organs with the major sites of systemic amyloid deposition being the kidneys, heart, GI tract, subcutaneous adipose tissues, and liver.
• In the glomeruli, larger fibrils can be found measuring approximately 20 nm in diameter. These large fibrils do not stain in Congo red incubations. The disease entity characterized by the deposition of such large Congo red–negative fibrils in glomeruli is named fibrillary glomerulopathy and should clearly be distinguished from amyloidosis).
