Production of abnormal proteins that form non-branching fibrils approximately 10 nm in diameter that have a cross beta-pleated sheet configuration on X-ray crystallography.
The etiologies of amyloidosis are many, including lymphoproliferative disorders such as myeloma/lymphoma, chronic longstanding inflammation such as rheumatoid arthritis, tuberculosis and osteomyelitis, familial/genetic, chronic hemodialysis and of course idiopathic.
The amyloid fibrils deposit in extracellular regions such as the glomerular mesangia and glomerular basement membranes rendering the glomerular filter leaky to plasma proteins, e.g. albumin.,
Being of diverse etiology, amyloidosis will be epedimiologically diverse.
Amyloidosis may be related to multiple myeloma, chronic long standing inflammatory processes such as rheumatoid arthritis and chronic osteomyelitis, chronic renal hemodialysis or be hereditary.
|General Gross Description|
The kidneys are usually normal size or larger than normal.
On cut section, the surface is firm and waxy.
In advanced stages, the kidney may be small and shrunken due to vascular compromise.
|General Microscopic Description|
Amyloid tends to be deposited in the glomerular mesangia, glomerular basement membranes and vessel walls giving these areas a hyaline appearance. .
There is no cellular response to the deposits and the areas affected appear acellular or hypocellular.
In advanced stages, the glomeruli may be completely replaced with amyloid material and appear acellular.
Deposits may also be in the interstitium.
Amyloid deposits are positive for Congo Red and Thioflavine T.
Cotran RS et al: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 236, 963.
Harrison's Principles of Internal Medicine, 13th Ed: Isselbach et. al. (eds). New York, McGraw-Hill, 1994, pp. 1184, 1417-1421.
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||Synopsis by: Harold Yamase M.D. (T71000M55100)