Light micrograph of a human kidney showing amyloid deposits (pink) in a glomerulus (centre) and around a renal arteriole (top left). Amyloid is composed of protein. Its deposition causes disruption of tissues, loss of functioning cells & if arteries are involved, a reduction in blood supply. It is associated with diseases such as rheumatoid arthritis & some cancers. This specimen is from a person with a 20 year history of rheumatoid arthritis. The kidneys are the organs most commonly involved in amyloidosis. Renal failure caused by widespread amyloidosis accounts for the majority of deaths from the disease. UFig. 4.2b BASIC HISTOPATHOLOGY