Amyloid is an extracellular eosinophilic substance without a fixed shape that can be present in different tissues and organs, resulting in a disease called amyloidosis. The amyloid is mainly composed of proteins, which are mostly arranged in a reverse beta-folded lamellar structure. In electron microscopy amyloid is arranged as protofibrils, and in case material as a large number of extracellular unbranched filaments, mostly randomly arranged. Histological methods used to identify amyloid material include methyl violet staining, Congo red staining, and polarized light microscopic observation.