What is the role of rectal biopsy in the diagnosis of amyloidosis?

Updated: May 09, 2019
  • Author: Robert O Holmes, Jr, DO; Chief Editor: Herbert S Diamond, MD  more...
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For many years, rectal biopsy was the first procedure of choice. An important clinical advance was the recognition that the capillaries in the subcutaneous fat are often involved in patients with systemic amyloidosis and can often provide sufficient tissue for the diagnosis of amyloid, immunostaining, and, in some cases, amino acid sequence analysis; thus, biopsy of the organ with the most severe clinical involvement is often unnecessary.

For example, in cardiac amyloidosis, the definitive diagnosis of the type of amyloid can be made using an endomyocardial biopsy specimen, with Congo red and immunologic staining of the tissue sample. Alternatively, when noninvasive testing suggests cardiac amyloidosis, studying a subcutaneous fat aspiration instead of endomyocardial biopsy, thereby avoiding an invasive procedure, often provides a specific diagnosis.

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