Amyloidosis

Amyloidosis, a chronic metabolic disease caused by the deposition of amyloid in tissues or organs. It can invade many organs throughout the body, or it can be limited to the skin. The cause is unknown. Amyloid is an amorphous substance that appears pink when stained with conventional hematoxylin-eosin (HE); purple-red when stained with periodic acid Schiff (PAS). Congo red staining is orange-red, apple green when viewed with a polarizing microscope, and lace-like. Includes several different proteins. The chemical reaction of such proteins is similar to starch, and has nothing to do with starch. The source of amyloid is unknown. It is the product of antigen-stimulated plasma cells or fibroblasts, or the product of degenerative basal keratinocytes. Skin-type amyloidosis is more common in clinics, and other types are rare.