Hi Dear, Welcome to HCM. Understanding your concern. As per your query you have numbness in your knee. Well kidney cysts are round pouches of fluid that form on or in the kidneys. Kidney cysts can be associated with serious disorders that may impair kidney function. But more commonly, kidney cysts are noncancerous cysts that rarely cause complications. I would suggest you to consult nephrologist for proper treatment . Doctor may opt non surgical methods like inserting a needle to drain the cyst and fill it with alcohol to that it will not occur again or may go for surgical method to remove the cyst depending upon the exact position and condition of cyst . If cyst is not interfering with kidney function , we can left it as its without any treatment until there will be any symptoms . Hope your concern has been resolved. Get Well Soon. Best Wishes, Dr. Harry Maheshwari