Familial amyloidosis diagnostic study of choice

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Fahimeh Shojaei, M.D.

Tissue biopsy with Congo red stain is the gold standard test for the diagnosis of amyloidosis. Biopsy may be taken from an affected organ such as kidney, or from subcutaneous fat or rectal mucosa. There are no established criteria for the diagnosis of familial amyloidosis.

• Tissue biopsy with Congo red stain is the gold standard test for the diagnosis of amyloidosis.^[1]

• Biopsy may be taken from an affected organ such as kidney, or from subcutaneous fat or rectal mucosa.
• The rectal mucosa biopsy is especially sensitive for:
  • Transthyretin (TTR)
  • Apolipoprotein AI
  • Apolipoprotein AII
  • Fibrinogen Aa
• Biopsy of the affected organ is recommended for patients with limited organ involvement.^[2]
• Biopsy from unaffected organs is more sensitive in patients with multi-organ involvement.

The following finding on tissue biopsy is confirmatory for familial amyloidosis:^[3][4]

• Apple green birefringence of the tissue sample under polarized light with Congo red stain.

The various investigations must be performed in the following order:

• History
  • Although all the familial amyloidosis types are autosomal dominant, different degree of temperance makes it difficult to diagnose the disease based on family history.
• Physical examination
• Biopsy

There are no established criteria for the diagnosis of familial amyloidosis.

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