1.What is a liver cyst? A liver cyst is commonly referred to as a “blister” in the liver, a vacuole in the liver that does not contain solid tissue. The vast majority of liver cysts are congenital, that is, due to some abnormalities in congenital development that lead to the formation of liver cysts. Acquired factors, such as people contracting encapsulated cysticercosis, produce parasitic cysts in the liver. Trauma, inflammation, and even tumors can also cause liver cysts. Hepatic cysts are mostly found in the right lobe of the liver and vary in size from a few millimeters in small ones to more than 10 centimeters in large ones, which are spherical or ovoid in shape, and most of the cyst fluid is clear liquid or bile. Most of the simple hepatic cysts are congenital bile duct cysts with very slow growth, some of them are parasitic and some of them may be caused by bile retention due to intrahepatic bile duct infection, edema or stones. Most liver cysts in the elderly are caused by degenerative lesions of the liver tissue. Patients with multiple hepatic cysts are sometimes combined with cysts of other internal organs, such as concomitant renal cysts, pulmonary cysts and occasionally pancreatic cysts and splenic cysts. Zheng Zhaomin, Department of Minimally Invasive Oncology, Shandong Qianfo Mountain Hospital, Shandong Province, China 2. Symptoms and hazards of liver cysts Liver cysts are asymptomatic in early stage, so it is difficult to diagnose clinically. The liver cyst grows slowly, and when the cyst grows to a certain extent and compresses the neighboring organs, symptoms such as fullness after eating, poor appetite, nausea, vomiting, abdominal discomfort and pain may appear. Obstructive jaundice caused by compression of bile ducts is less common. In a few cases, rupture of the cyst, intracapsular bleeding, and torsion of the cyst with the tip may cause acute abdomen. In case of intracapsular infection, there are chills, fever and elevated white blood cells, and on physical examination, there may be a large liver or epigastric mass. In the danger of liver cyst, about 50% of patients have combined polycystic kidney, which may have symptoms such as hypertension, hematuria, pain in kidney area and renal insufficiency. When the risk of liver cyst is complicated by cyst infection, bleeding, rupture or torsion, it is manifested by sudden severe abdominal pain, high fever, or signs and symptoms of peritonitis.3. Clinical diagnosis Liver cyst mainly relies on imaging examination for diagnosis. Ultrasound examination is the most important among the imaging diagnoses, and ultrasound is the preferred examination method, which is an economical, reliable and non-invasive simple method to diagnose liver cysts; CT examination can detect liver cysts of 1 to 2 cm, which can help clinicians to accurately localize the lesions, especially the distribution status of multiple cysts, and facilitate treatment. Liver cysts do not cause abnormalities in liver function. However, sometimes some blood tests are still necessary for differential diagnosis. 4.Treatment of liver cysts In principle, for the treatment of tumor, when the cyst is less than 5 cm and there is no symptom, no treatment can be done, but regular review of ultrasound and observation of the change of cyst size can be done. If the cyst is larger than 5 cm and there is discomfort, treatment can be considered. (1) Chinese medicine can treat liver cysts, however, the efficacy varies and it takes a long time to take the medicine. Neither Chinese nor Western medicine can make the cyst disappear or shrink. (2) Surgical treatment. The disadvantages of open surgery are high trauma, pain, slow recovery, long course of disease and more surgical complications. Laparoscopic treatment patients need to be treated under general anesthesia. (3) Ultrasound-guided interventional treatment of cyst At present, interventional treatment is the most effective treatment means. Under the guidance of ultrasound or CT, the shortest and safest route is chosen, and a fine needle is accurately pierced into the cyst cavity through the skin, and a drainage catheter is placed inside the cyst cavity (pigtail catheter) under the guidance of a guiding wire, and the cyst fluid inside the cyst is first pumped clean, and then a certain amount of anhydrous alcohol is injected into the cyst cavity. Wait for a moment and then draw out the anhydrous alcohol, repeatedly fix the catheter bandage 1 to 2 times, and repeat the flushing once each on the 2nd to 3rd day, after which the drainage tube can be removed. The purpose of anhydrous alcohol injection is to destroy the cells of the cyst wall and make the cyst harden and not grow again. Interventional treatment of cysts does not require incision, local anesthesia, very fine puncture needles, safety, little pain, good efficacy and very few complications. Interventional treatment of liver cysts, kidney cysts, pancreatic cysts, and ovarian cysts is highly effective. It is even safer and more effective than surgery for some special parts of lesions that are not suitable for surgery.