Kidney cyst 12x12mm is usually not serious, kidney cyst is a common disease in urology, it is a cystic mass that occurs in the kidneys, and in most cases it is benign. The cause of its pathogenesis is not clear, and patients usually have no obvious symptoms, often found on physical examination or examination of other diseases when doing ultrasound. If the diameter of cyst is less than 5㎝ and there is no obvious discomfort, it can be left untreated and continue to be observed without any effect on the body. Therefore, kidney cyst 12x12mm does not affect the body and is not serious. However, there is one situation that should be noted, that is, if the kidney cyst increases significantly in a short time or the wall of the cyst is calcified, it should go to the urology department of regular public hospital in time for diagnosis and treatment.