Which histologic findings are characteristic of AA (inflammatory) amyloidosis?

Updated: Jan 08, 2021
  • Author: Jefferson R Roberts, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

Infiltrated tissues show homogeneous eosinophilic staining with hematoxylin and eosin. The earliest deposits are usually vascular. In the kidney, early deposits may be mesangial, but, late in the course, entire glomeruli may be obliterated. Distinguishing these from glomerulosclerosis and from other causes is difficult prior to Congo red staining. Congo red binding by itself may be observed in other states, particularly in collagen-rich tissues, but the green birefringence is characteristic on examination with polarized light and the amyloid nature of the deposit can be demonstrated by observing the characteristic beta pleated sheet on electron microscopy. The nature of the precursor can be established with certainty using antisera specific for various amyloid precursors. In this case, staining with anti-AA serum is positive, as described above.


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