Stomach
Other nonneoplastic lesions
Amyloid


Topic Completed: 1 July 2012

Revised: 20 March 2019

Copyright: 2003-2019, PathologyOutlines.com, Inc.

PubMed Search: gastric amyloid

Elliot Weisenberg, M.D.
Page views in 2019: 1,007
Page views in 2020 to date: 180
Cite this page: Weisenberg E. Amyloid. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/stomachamyloid.html. Accessed April 1st, 2020.
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
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