Stomach
Other nonneoplastic
Amyloid
Author: Elliot Weisenberg, M.D.
Last author update: 1 July 2012
Last staff update: 1 September 2020
Copyright: 2003-2024, PathologyOutlines.com, Inc.
PubMed Search: gastric amyloid
Table of Contents
Definition / general | Gross description | Microscopic (histologic) description | Positive stains | Electron microscopy descriptionCite this page: Weisenberg E. Amyloid. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/stomachamyloid.html. Accessed December 22nd, 2024.
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
