Kidney cyst

A fluid-filled sac in the kidney. Most kidney cysts are noncancerous. Cysts commonly develop in people over 50 and may occur singly or multiply in 1 or both kidneys. Most cysts occur for no known reason and do not usually produce symptoms unless they become large enough to cause pain in the lower back due to pressure. However, large numbers of cysts in the kidneys may be associated with polycystic kidney disease (see kidney, polycystic), which often leads to kidney failure. Treatment of simple cysts is not usually necessary, but aspiration (withdrawal of fluid) or surgical removal may be carried out if a cyst is painful or recurs.


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