Amyloidosis

Amyloidosis is a heterogeneous disease or even considered a constellation of diseases resulting in a deposition relatively similar proteins. It has many causes and can affect essentially any organ system.

Epidemiology 

There may be male predilection. Typically affects middle aged individuals aged around 60 years 5.

Pathology

Amyloid comprises a group of proteins characterised by certain physical properties. There are at least 15 amyloid proteins can be derived from diverse precursors. Some demonstrate structural morphology with immunoglobulins. 

Subtypes

In certain scenarios the amyloid proteins are produced and deposited locally, whereas in others the protein is distributed systemically. 

Systemic amyloidosis

The majority occur in the the systemic form

  • AL (amyloid light chain)
    • synthesised by plasma cells, and seen in conditions with monoclonal proliferation of these cells
  • AA (amyloid associated)
    • derived from SAA (serum associated amyloid-associated) protein which is synthesised by the liver and forms part of the HDL3 lipoproteins
    • typically seen in chronic inflammatory disease, or familial mediterranean fever
  • 2M: derived from ß2-microglobulin, and seen in patients on haemodialysis
  • ATTR (amyloidtranthyretin)
    • seen in senile systemic amyloidosis / neuropathic cerebral angiopathy
    • is the most common form of familial amyloidosis 5
Localised amyloidosis

Accounts for ≈15% of amyloidosis

  • A4ß2 (beta amyloid protein): seen in Alzheimer disease
  • AANF (atrial natriuretic factor): isolated atrial amyloidosis
  • AIAPP (islet amyloid peptide): deposited in the pancreas in patients with type II diabetes mellitus
  • ACal: seen in medullary islet cell tumour
Organ-specific amyloidosis

Amyloid deposition can occur in essentially any part of the body, although some are more common and have specific imaging findings. These conditions are best discussed separately:

Histology

Amyloid is an insoluble extracellular proteinaceous substance composed of cross-ß-pleated sheets which have the property of apple-green birefringence when viewed under polarised light 1. A pink-red coloration is seen with the Congo red stain.

Associations 
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Article Information

rID: 6720
Section: Pathology
Tag: cases
Synonyms or Alternate Spellings:
  • Amyloidosis (general)

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    Figure 1: duodenal amyloid deposition
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    Mediastinal amylo...
    Case 1: mediastinal amyloidoma
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    Case 2: gastrointestinal amyloidosis
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