Cardiac amyloidosis

What it means

Extracellular deposition in cardiac tissue of a proteinaceous material that, when stained with Congo red, demonstrates apple-green birefringence under polarized light and that has a distinct color when stained with sulfated Alcian blue. Viewed with electron microscopy, the amyloid deposits are seen to be composed of a beta-sheet fibrillar material. These nonbranching fibrils have a diameter of 7.5 to 10 nm and are the result of protein misfolding.

The diagnosis of amyloidosis requires histological identification of amyloid deposits. Congo Red staining renders amyloid deposits salmon pink by light microscopy, with a characteristic apple green birefringence under polarized light conditions. Additional immunohistochemical staining for precursor proteins identifies the type of amyloidosis.

Rare diseases that can present with this6

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Amyloid cardiomyopathy