The substance inside the cyst is water, or cystic fluid, with a membrane on the outside that wraps it to form a mass, described as a cyst under ultrasound or CT. Cysts are benign lesions that do not form malignant tumors and tend to occur within the parenchyma of the liver or the parenchyma of the kidney. Small cysts that do not cause pressure symptoms can be followed up with ultrasound review every six months or a year to understand the changes of cysts. If the cyst is large and has compression symptoms, or causes discomfort such as vague pain or pain in the liver or kidney area, surgery can be considered, and laparoscopy is generally used to open a window on the surface of the cyst to drain the cystic fluid completely to the outside.