The Systemic Amyloidoses

Abstract

Amyloidosis is not a single disease but a term for diseases that share a common feature: the extracellular deposition of pathologic insoluble fibrillar proteins in organs and tissues. In the mid-19th century, Virchow adopted the botanical term “amyloid,” meaning starch or cellulose, to describe abnormal extracellular material seen in the liver at autopsy.¹ Subsequently, amyloid was found to stain with Congo red, appearing red microscopically in normal light but apple green when viewed in polarized light.^2,3 Almost a century after Virchow's observations, the fibrillar nature of amyloid was described with the use of electron microscopy and the characteristic beta-pleated–sheet . . .