Simple kidney cysts are generally harmless, while cysts associated with polycystic kidney disease can be dangerous and have the potential to lead to kidney failure, according to the National Kidney Foundation. Irregular cysts can be a sign of kidney cancer, states Cleveland Clinic.
Simple kidney cysts rarely display any symptoms and usually do not require treatment. In some cases, a cyst may cause pain or interfere with kidney function, and a doctor may choose to drain the cyst or remove it with surgery, says the National Kidney Foundation.
Polycystic kidney disease is a condition in which a large number of cysts can replace normal kidney tissue and result in a loss of kidney function. Polycystic kidney disease may also affect other organs, and it can be particularly problematic if it affects the brain or the heart, states the National Kidney Foundation.