Other nonneoplastic


Topic Completed: 14 April 2021

Minor changes: 21 April 2021

Copyright: 2003-2021,, Inc.

PubMed search: Colon[TIAB] amyloidosis[TI]

Raul S. Gonzalez, M.D.
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Cite this page: Gonzalez RS. Amyloidosis. website. Accessed October 18th, 2021.
Definition / general
  • Extracellular deposition of amyloid protein, often around blood vessels
Essential features
  • Amyloid deposition in the colon, confirmable with Congo red
  • Usually around blood vessels, which can lead to vascular injury
  • Localized (limited to the colon) or diffuse (present in numerous organs)
  • Can be primary, secondary, hereditary or endocrine related
  • Overproduction of amyloid protein (AL, AA, ATTR, etc.) due to various causes
  • Senile amyloid is often present in GI tract of elderly patients (Pathol Res Pract 1994;190:641)
Clinical features
  • Gastrointestinal involvement is seen in most patients with systemic amyloidosis
  • May be asymptomatic or cause bleeding, obstruction, perforation or abnormal motility
  • Amyloid tumor may clinically resemble carcinoma (AJR Am J Roentgenol 2002;179:536)
  • Uncommonly, amyloid is localized to colon and does not require systemic treatment (Amyloid 2003;10:36)
  • Can diagnose with rectal biopsy that includes submucosa (85% sensitivity), though amyloid deposition may be initially discovered in a resection specimen
Radiology description
Case reports
  • If systemic, depends on type of amyloid but generally targeted at the cause (myeloma, kidney failure, etc.)
Gross description
  • Mucosa may be normal or finely granular
Gross images

Images hosted on other servers:

Amyloid tumor (above)
and adenocarcinoma
arising from villous
adenoma (below)

Microscopic (histologic) description
  • Amyloid present in blood vessel walls and muscularis propria; may be subepithelial; may cause ischemic changes or frank hemorrhage
Microscopic (histologic) images

Contributed by Raul S. Gonzalez, M.D.
Colonic amyloid Colonic amyloid

Colonic amyloid

Images hosted on other servers:

Submucosal vessel involvement

With Congo red stain

Congo red stain
highlights vessel
wall and free
submucosal amyloid

Congo red stain

deposits resembling
collagenous colitis

Positive stains
  • Congo red (stains deep pink and demonstrates apple green birefringence, as in other body sites)
Sample pathology report
  • Colon, splenic flexure, biopsy:
    • Amyloidosis (see comment)
    • Comment: The biopsy shows amorphous eosinophilic material present around submucosal blood vessels. On Congo red stain, the material demonstrates apple green birefringence.
Differential diagnosis
Additional references
Board review style question #1

Which of the following stains would be positive in the amorphous perivascular material seen in this colon polyp?

  1. AFB
  2. Congo red
  3. GMS
  4. von Kossa
Board review style answer #1
B. The material is amyloid. It would stain a salmon pink color with Congo red and demonstrate apple green birefringence.

Comment Here

Reference: Amyloidosis
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