What is the role of organ biopsies in the diagnosis of amyloidosis?

Updated: Nov 12, 2018
  • Author: Robert O Holmes, Jr, DO; Chief Editor: Herbert S Diamond, MD  more...
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Answer

It is important to recognize that not all biopsy sites offer the same sensitivity. The best sites from which to obtain a biopsy specimen in systemic amyloidosis are the abdominal fat pad and rectal mucosa (approaching 90% sensitivity for fat pad and 73-84% for rectal mucosa). [80] While some imaging modalities can strongly suggest amyloidosis, a tissue sample showing birefringent material is still the criterion standard. This is definitely the case in terms of cardiac specific amyloid. While, endomyocardial biopsy is the best confirmatory test for local cardiac amyloid deposition, it can be very risk averse and requires a center of excellence with the full complement of immunohistochemical and molecular-based testing. [81]

When the subcutaneous fat aspiration biopsy (the least invasive biopsy site) does not provide information to reach a firm diagnosis, biopsy specimens can be obtained from other organs. In addition, an advantage to performing a biopsy of an involved organ (eg, kidney, heart) is that it definitively establishes a cause-and-effect relationship between the organ dysfunction and amyloid deposition.

Other sites that are often sampled but have poor sensitivity for the diagnosis of amyloid include the salivary glands, skin, tongue, gingiva, stomach, and bone marrow. A recent study suggests that the duodenum may be the most sensitive biopsy site compared with the gingiva, esophagus, or gastric antrum in AA renal disease. [82]


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