Polycystic kidney disease (PKD) is an inherited disorder in which clusters of cysts develop primarily within your kidneys. Cysts are noncancerous round sacs containing water-like fluid. The cysts vary in size and, as they accumulate more fluid, they can grow very large. Although kidneys usually are the most severely affected organs, polycystic kidney disease can cause cysts to develop in your liver and elsewhere in your body. The disease causes a variety of serious complications. A common complication of polycystic kidney disease is high blood pressure.