Overview Amyloid is misfolded protein that takes the form of a beta-pleated sheet the protein cannot be degraded by cellular enzymes results in accumulation in the extracellular space the deposited mass of the misfolded protein is damaging to tissues Diagnosis made by demonstrating apple-green birefringence of Congo red stain under polarized light Amyloid can form from a variety of proteins but the above characterisitic are shared properties Amyloid can be localized or systemic Systemic Amyloidosis Affects the entire body and can be of primary or secondary cause Primary result of AL amyloid deposition derived from Ig light chain classically seen in multiple myeloma Secondary result of AA amyloid deposition derived from acute phase reaction of inflammation associated with increased levels of IL-6 can see with rheumatoid arthritis or other forms of chronic inflammation Clinical findings deposition in glomerulus results in nephrotic syndrome deposition in the heart results in arrhythmias and/or restrictive cardiomyopathy deposition in liver, spleen, tongue, intestine Localized Amyloidosis Affects only a specific organ Localized Amyloidosis Types Protein Derived from Senile cardiac AF Transthyretin Isolated Atrial AANF Atrial Natriuretic Peptide (ANP) Diabetes mellitus type 2 AE Amylin Medullary carcinoma of the thyroid A-CAL Calcitonin Alzheimer's disease β-amyloid Amyloid precursor protein (APP) Dialysis-associated β2-microglobulin MHC class I proteins