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212 SECtIoN II Pathology ` PATHOLOGY—CeLLuLAr InjurY Pathology ` PATHOLOGY—InfLAMMATIOn

Amyloidosis Abnormal aggregation of proteins (or their fragments) into β-pleated linear sheets Ž insoluble
fibrils Ž cellular damage and apoptosis. Amyloid deposits visualized by Congo red stain
(red/orange on nonpolarized light [arrows in A ]), (apple-green birefringence on polarized light
[arrows in B ]), and H&E stain (shows deposits in glomerular mesangial areas). Tubular basement
membranes are enlarged on light microscopy.
COMMOn TYPeS fIBrIL PrOTeIn DeSCrIPTIOn
Systemic
Primary amyloidosis AL (from Ig Light chains) Seen in Plasma cell disorders Manifestations include:
(eg, multiple myeloma) ƒ Cardiac (eg, restrictive
Secondary Serum Amyloid A Seen in chronic inflammatory cardiomyopathy)
amyloidosis (AA) conditions, (eg, rheumatoid ƒ GI (eg, macroglossia,
arthritis, IBD, familial hepatomegaly)
Mediterranean fever, protracted ƒ Renal (eg, nephrotic
infection) syndrome)
ƒ Hematologic (eg, easy
Dialysis-related β 2 -microglobulin Seen in patients with ESRD bruising, splenomegaly)
amyloidosis and/or on long-term dialysis
ƒ Neurologic (eg, neuropathy)
ƒ Musculoskeletal (eg, carpal
tunnel syndrome)
Localized
Alzheimer disease β-amyloid protein Cleaved from amyloid precursor
protein (APP)
Type 2 diabetes Islet amyloid polypeptide Caused by deposition of amylin
mellitus (IAPP) in pancreatic islets
Medullary thyroid Calcitonin
cancer
Isolated atrial ANP Common in normal aging
amyloidosis  risk of atrial fibrillation
Systemic senile (age- Normal (wild-type) Seen predominantly in cardiac Cardiac dysfunction more
related) amyloidosis transthyretin (TTR) ventricles insidious than in AL
amyloidosis
Hereditary
Familial amyloid Mutated transthyretin Ventricular endomyocardium 5% of African Americans are
cardiomyopathy (ATTR) deposition Ž restrictive carriers of mutant allele
cardiomyopathy, arrhythmias
Familial amyloid Mutated transthyretin Due to transthyretin gene
polyneuropathies (ATTR) mutation
A B

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