Polycystic kidney. Gross specimen of a polycystic human kidney. This specimen is 18 centimetres long. Polycystic kidney disease is one of the most common causes of chronic kidney failure in adults. It is an inherited condition that may remain dormant with renal function preserved until middle life. The polycystic kidney is enlarged and cysts will also be found throughout the cortex and medulla (the internal structures of the kidney). The condition results in renal failure, but such failure is now treatable by either dialysis or transplantation, depending on the severity of the condition.