The cortical cyst / cortical renal cyst refers to a very common type of kidney cyst. Because it is located at the renal cortex, it is called the cortical cyst. It is a fluid-filled sac growing in the outer area of the kidneys. You might have one, or you might have several, and they can affect just one or both kidneys.
No one knows for sure what causes a cortical cyst. It might be caused by infections, injuries or genetic issues. Scientists do know that they occur more often in men than in women, and the older you get, the better your chances are for developing them.
Very small cysts might cause no problems at all, and you might not know you have the cyst until it is found in a routine examination for other issues. As the cyst grows larger, you might start to feel pain or pressure in your back or sides, which often radiates downward. The pain is usually dull, not sharp. When it becomes big enough, you might be able to feel it when you press down on your abdomen. You might notice blood or bubbles in your urine. You might also begin to experience problems with high blood pressure.