Other non-neoplastic lesions

Author: Elliot Weisenberg, M.D. (see Authors page)

Revised: 29 November 2016, last major update July 2012

Copyright: (c) 2003-2016,, Inc.

PubMed Search: gastric amyloid
Cite this page: Amyloid. website. Accessed October 18th, 2018.
Definition / general
  • 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

  • Symptoms:
    • 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
Microscopic (histologic) 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