Amyloidosis
Sanjay Kakar, MD
Key Facts
Etiology/Pathogenesis
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Liver involvement may be seen in AL, AA, and hereditary amyloidosis
Microscopic Pathology
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Sinusoidal pattern is more common in AL amyloidosis and vascular pattern in AA amyloidosis
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Distribution patterns show overlap and are not reliable for definite distinction between AL and AA amyloidosis
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Amyloid deposits are congophilic and show “apple green” birefringence under polarized light
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Birefringence is best demonstrated by turning light to maximum and pulling color filters out
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Immunohistochemistry for light chains and SAA help in further classification
Deposits are seen in the hepatic arteriole  and portal vein  in the vascular pattern of hepatic amyloidosis. This distribution is characteristic, but not specific, for the AA form. |
Congo red stain highlights the vascular distribution of amyloid deposits in the hepatic arteriole  and portal vein  . |
TERMINOLOGY
Definitions
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Heterogeneous group of diseases characterized by deposition of glycoprotein fibrils in extracellular matrix and vessel walls
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Deposits composed of low molecular weight subunits (5-25 KDa) derived from normal serum proteins
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Liver involvement may be seen in all 3 types
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Primary, or AL, amyloidosis
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Deposits are composed of fragments of monoclonal light chains
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Occurs alone or associated with other hematologic diseases (plasmacytoma, multiple myeloma Waldenstrom macroglobulinemia)
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Liver involved in up to 70% of cases
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Hepatic involvement reflects advanced disease and denotes poor prognosis
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Secondary, or AA, amyloidosis
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Deposits are composed of fragments of serum amyloid A (SAA) protein, an acute phase reactant
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