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Other non-neoplastic lesions


Reviewer: Elliot Weisenberg, M.D. (see Reviewers page)
Revised: 2 August 2012, last major update July 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.


● Deposition of insoluble extracellular protein, usually AL (light chains associated with myeloma) or AA (acute phase proteins secondary to chronic inflammation or familial Mediterranean fever) types
● Also associated with chronic dialysis (β2-microglobulin)
● Rarely idiopathic
● 70% of cases of AL amyloidosis and 55% of AA amyloidosis involve GI tract, often stomach
● Primary amyloidosis (AL) patients often have monoclonal proteins in serum/urine

● Frequently none
● Bloating, pain, obstruction, hematemesis, hemorrhage

Gross description

● Usually normal (multiple biopsies recommended in patients with systemic amyloidosis)
● May have diffuse involvement and form a mass

Micro description

● Appears as amorphous, waxy, salmon pink material, often with shatter artifact
● Often infiltration around blood vessels deep to mucosa

Positive stains

● Congo red (red/green birefringence under polarized light), Thioflavin immunofluorescence

Electron microscopy description

● 7.5 to 10 nanometer fibrils in twisted beta-pleated sheets

End of Stomach > Other non-neoplastic lesions > Amyloid

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