Amyloidosis is the deposition into tissues of a substance which Virchow called amyloid because of its resemblance to starch. It is a mucopolysaccharide-protein complex which changes the color of iodine as starch changes it, and it is specific in its absorption of Congo red and methyl violet. According to Peters,1 the substance is deposited in extracellular spaces, forming on tissues as a product of a disturbed protein metabolism of the cellular membranes. Larsen2 has suggested that amyloid forms on tissues because of a change in the capillary permeability not associated with any alteration of tissues.
Many theories have been developed in an attempt to determine the etiology of amyloidosis. Amyloid deposits have been considered the product of a disturbance of protein metabolism, the result of an antigen-antibody reaction, and the consequence of a reticuloendothelial disturbance, and, in those cases associated with multiple myeloma, it has been suggested that