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[ am″ĭ-loi-do´sis ]
the deposition in various tissues of amyloid. This protein is almost insoluble and once it infiltrates the tissues they become waxy and nonfunctioning. Primary, or immunocyte-derived, amyloidosis is thought to be due to some obscure metabolic disturbance in which there is an abnormal protein in the plasma; the tissues most often affected are cardiac and smooth and skeletal muscle tissue. Secondary, or reactive systemic, amyloidosis is related to chronic suppuration, especially those types associated with tuberculosis, lung abscess, osteomyelitis, or bronchiectasis; it may also occur in association with chronic noninfectious inflammatory disease, such as rheumatoid arthritis. The most common sites of deposition are the spleen, kidney, liver, and adrenal cortex.
Etymology: Gk, amylon + eidos, form, osis, condition
a disease in which a waxy, starchlike glycoprotein (amyloid) accumulates in tissues and organs, impairing their function. The condition may be hereditary or acquired and may be systemic or organ specific. Primary amyloidosis refers to light chain amyloidosis seen in multiple myeloma. Patients with secondary amyloidosis usually suffer from another chronic infectious or inflammatory disease, such
as tuberculosis, osteomyelitis, rheumatoid arthritis, or Crohn's disease. Almost all organs can be affected, most often the heart, lungs, tongue, and intestines in primary amyloidosis, and the kidneys, liver, and spleen in the secondary type. Elderly patients tend to experience cardiac effects of the disease. Diagnosis is made through biopsy of the suspected organ or abdominal fat aspiration. There is no known cure for amyloidosis, and treatment in the secondary type is aimed at alleviating the underlying chronic disease. Patients with renal amyloidosis are frequently candidates for kidney dialysis and transplantation.
A large group of diseases characterised by misfolding of extracellular protein. Insoluble toxic proteins are deposited as bundles of β-sheet fibrillar protein, either in specific organs (localised amyloidosis) or systemically (systemic amyloidosis). It can be primary or secondary to other conditions (e.g. tuberculosis, cancer, leprosy) and accompanied by immune changes.
Primary amyloidosis (AL amyloidosis, idiopathic amyloidosis)
An uncommon condition associated with plasma cell dyscrasias, where the accumulated amyloid fibres correspond to fragments of Ig light chains.
Secondary amyloidosis (AA amyloidosis, reactive amyloidosis)
A group of conditions seen in chronic inflammation and multisystem disease, in which amyloid derives from a circulating acute-phase lipoprotein (serum protein 1).