Congenital liver cysts

　　One, Etiology

　　1. The cause is not yet fully clear, and there are two viewpoints: one is the developmental abnormality of bile ducts or lymphatic vessels in the embryonic liver, or the formation of wandering bile ducts in the liver; the other is that the infection in the embryonic liver causes cholangitis, leading to atresia of small bile ducts in the liver, and the proximal small bile ducts gradually become cystic and expand to form cysts. Congenital developmental disorders can be caused by heredity, such as adult polycystic liver disease (adult polycystic liver disease, APLD), which is an autosomal dominant genetic disease.

　　2. According to Debakey's etiological classification, congenital liver cysts can be divided into two major categories: primary parenchymal liver cysts and primary biliary cystic liver cysts. The former is divided into: ① Isolated liver cyst (which can be a single or multiple liver cysts); ② Multicystic (polycystic) liver cysts (i.e., polycystic liver). The latter is divided into: ① Localized intralobular main bile duct dilatation; ② Multiple cystic dilatation of intralobular bile ducts (i.e., Calori disease). This article only describes congenital parenchymal liver cysts, or true cysts, to distinguish them from pseudocysts caused by trauma, inflammation, tumors, etc.

　　Two, Pathogenesis

　　1. Solitary liver cysts can be very small or very large, with the diameter of the small ones only a few millimeters, and the large ones can reach more than 20 cm, even occupying the entire lobe of the liver. However, the liver cysts seen in clinical practice are usually large, with a fluid content often exceeding 500 ml, and the maximum can reach 17,000 ml. In a group of cases from Shanghai Oriental Hepatobiliary Surgery Hospital, there was one case where the cyst fluid reached 5000 ml. The cysts are usually round or elliptical, mostly solitary, but sometimes can be multicystic, and may even have a pedicle. The cysts have a complete capsule, with a surface that is milky white or blue-gray. The thickness of the cyst wall varies, with the thick ones reaching 0.5 to 5.0 mm, the inner layer being columnar epithelial cells, and the outer layer fibrous tissue, covered with larger bile duct and vascular bundles. The surrounding liver cells are often atrophic and degenerate due to compression. The cyst fluid is usually clear and transparent or mixed with bile. If there is bleeding within the cyst, it can appear coffee-colored. The cyst fluid is neutral or alkaline, with a density of 1.010 to 1.022, containing a small amount of albumin, mucin, cholesterol, red blood cells, bilirubin, tyrosine, or bile, etc.

　　2. Multiple liver cysts are more common than solitary cysts. The size of the cysts varies, with small ones being as large as mung bean seeds or only visible under a microscope, and large ones can have a volume of more than 1000ml. Cysts can be scattered throughout the liver or concentrated in one lobe, with the right lobe being more common. The gross specimen shows a honeycomb-like change, and the cyst wall can be divided into two layers. The inner layer is composed of epithelial cells, which can vary in shape depending on the size of the cyst. Larger cysts, due to compression of the epithelial cells, the columnar cells and goblet cells appear flattened or disappear; medium-sized cysts only have goblet cells; small cysts have both columnar cells and goblet cells. The outer layer is collagenous tissue, and there are a number of small bile ducts and normal liver cells between the cysts. The cyst fluid is clear and transparent and generally does not contain bile. Multiple liver cysts rarely cause portal hypertension and esophageal varices, but can be associated with bile duct stenosis, cholangitis, and hepatitis. In the late stage, it can cause liver function damage, leading to ascites, jaundice, splenomegaly, esophageal varices, or varicose veins on the abdominal wall.

　　Complications are relatively rare, and the most common symptom is intracystic hemorrhage, which is manifested by sudden and severe abdominal pain and enlargement of the cyst. This complication is almost always seen in women over the age of 50, but in a very few patients, the abdominal pain is mild or even absent, and the cyst contents appear mobile under ultrasound during bleeding. In addition, when the cyst ruptures or there is concurrent infection within the cyst, chills and high fever may occur; compression of the duodenum can form an internal fistula; portal hypertension, etc. In 1977, Kasai et al. reported 3 cases of liver cyst wall carcinoma, pointing out that if the contents of the cyst are turbid and there are irregular nodules on the cyst wall, one should be vigilant about the possibility of malignant transformation. In addition, multiple cysts can also be associated with bile duct stenosis, cholangitis, and other conditions.

　　Patients with congenital liver cysts often have no symptoms in their youth, but symptoms gradually appear after the age of 35 to 40,表现为上腹部肿块，肝区及上腹部疼痛，usually as a mild pain, but if there is bleeding within the cyst, it can also be accompanied by severe abdominal pain; the compression of the cyst on adjacent organs can also cause a decrease in food intake, bloating, vomiting, jaundice, and other symptoms; a few severe liver cysts can also cause ascites, portal hypertension, and other manifestations in patients with concurrent cysts in other organs. Clinical examination in the early stage often shows no positive findings. For larger liver cysts, palpation can detect a mass in the upper right abdomen, which is smooth, tough, and can be accompanied by tenderness if there is infection.

　　Patients with congenital liver cysts often have no symptoms in their youth, but gradually appear symptoms after 35-40 years old, which seriously affects the daily life of patients, so it is necessary to take active preventive measures. Do a good job in prenatal examinations, discover congenital liver cysts early, and carry out targeted treatment.

　　For congenital liver cysts without complications, even if the cyst is large, it usually does not affect liver function, so laboratory tests rarely have positive results. When complications occur, patients may show elevated levels of liver bilirubin, transaminases, alkaline phosphatase, and transpeptidase; patients with infections may show elevated levels of blood leukocytes and classifications.

　　1. X-ray:Abdominal X-ray films can show calcification of the liver cyst wall in the form of an arc or complete calcification of the cyst; pneumoperitoneal contrast sometimes shows localized smooth and regular突出块影 on the liver surface; when the cyst compresses the gastrointestinal tract, barium meal contrast shows the displacement of the gastrointestinal tract; angiography can show the arterial branches around the cyst in a ball-like displacement, without tumor vessels, and clear filling defects appear at the substance phase, with certain diagnostic significance for liver cysts in ordinary X-ray imaging, but without specificity, generally not used.

　　2. Ultrasound:Circular or elliptical echo-free areas appear in the liver, which can be single or multiple, scattered in the liver parenchyma. The cyst wall is a thin, thin echo, with a clear boundary from surrounding tissues. In multilocular cysts, there may be single or multiple intervals with light bands, with varying thickness and width. Ultrasound imaging diagnosis is easy, with high accuracy and specificity, easy to follow up, and helpful in distinguishing from extraperitoneal abdominal cysts. At the same time, renal ultrasound should be listed as routine.

　　3. CT:Typical congenital liver cysts are characterized by smooth and sharp edges, round or elliptical low-density shadows, with CT values similar to or slightly higher than water. When the cysts are close to the liver capsule or adjacent to each other, very thin cyst walls can be shown. Occasionally, thickened and calcified cyst walls can be seen. Cysts are mostly unilocular, and occasionally there are septa. After intravenous injection of contrast agent, there is no enhancement in the cyst cavity. If liver cysts are found in CT scanning, especially in multicystic lesions, it is routine to scan the kidneys, spleen, pancreas. If multiple cysts are also found, they can be used as auxiliary diagnostic criteria for APLD.

　　4. Radionuclide imaging:Using radioactive nuclides such as 198Au and 131I for liver scanning can help determine whether there are space-occupying lesions in the liver, which is helpful in distinguishing between intraperitoneal and extraperitoneal cysts, and shows as a circular or large-scale radiating defect or sparseness with a regular edge, which is helpful for the localization diagnosis of cysts.

　　5. MRI:The sensitivity of liver cyst diagnosis is higher than that of CT, which can show cysts of 1cm in size and can distinguish the cystic dilatation of bile ducts, but MRI is difficult to differentiate between liver cysts and cavernous hemangiomas in differential diagnosis.

　　Cystic liver disease is one of the most common benign liver diseases, so patients with liver cysts generally have no serious problems, their diet is almost the same as that of ordinary people, but they should pay attention to the following points:

　　1. Change the habits of daily diet, reduce the fat content and total calorie intake in food.

　　2. Pay attention to rest and avoid overexertion.

　　3. Appropriate physical exercise to enhance physical fitness.

　　4. Vitamin A, B vitamins, vitamin C, vitamin B6, and vitamin E can reduce the risk of liver cyst development and can be taken in appropriate amounts.

　　5. Diet should be light, drink less alcohol, change daily dietary habits, avoid spicy, greasy, and irritating foods with high fat content, and reduce the fat content and total calorie intake in food.

　　1. Treatment

　　For the treatment of congenital liver cysts, the first step is to establish an accurate diagnosis to prevent misdiagnosis of some malignant or potentially malignant cystic lesions as congenital cysts, which may delay treatment. Liver cystic adenomas are prone to malignant transformation and should be distinguished from congenital cysts for surgical treatment. Congenital cysts without symptoms generally do not require surgical intervention, as the incidence of complications and the rate of malignancy are very low, and treatment is generally only used for symptomatic congenital cysts. Currently, there are mainly two treatment methods: surgery and interventional therapy. Puncture and aspiration for decompression can only be used as a temporary measure to relieve compression symptoms rather than definitive treatment, as the intracystic pressure has a certain regulatory effect on the secretion rate of cyst fluid. When the intracystic pressure is reduced, the secretion of cyst fluid increases and quickly returns to the intracystic pressure before puncture, exacerbating the symptoms. However, in cases of large congenital cysts, puncture and aspiration can be used for preoperative preparation to avoid severe physiological disturbances caused by sudden decompression when a large cyst is opened.

　　The treatment of congenital liver cysts has included relatively conservative methods in the past, such as cyst puncture and aspiration, intracystic injection of sclerosing agents, cyst fenestration, cystorrhaphy, and cystoenteric drainage. These methods all have drawbacks, including: recurrence of cysts; cyst infection; inability to effectively manage cyst complications; and inability to eliminate the possibility of malignant transformation. The therapeutic effect is not satisfactory. With the development of liver surgery to date, for solitary and localized congenital liver cysts, cystectomy and resection of the liver lobe (or segment) including the cyst are commonly used, which is relatively safe and effective. Multiple cyst punctures, injections of sclerosing agents, and internal drainage procedures can lead to cystic infection, increasing the difficulty of surgery and even causing severe complications such as postoperative infection. Madanaga et al. reported that in 44 cases of liver cystic lesion resection surgery, 1 patient died, who had received multiple puncture and aspiration treatments over the years, with infected cysts. The patient died due to massive hemorrhage during the resection of the right liver lobe, where the cyst was tightly adhered to the diaphragm, inferior vena cava, and right hepatic vein. In congenital liver cysts without infection or those that have received other treatments, adhesions are rare, and surgical resection is generally safe and easy. We believe that cystectomy should be the first-line surgical method for diseases such as solitary congenital cysts, localized multiple cysts, liver cystic adenomas that cannot be ruled out as malignant, and cystic lesions suspected of being malignant. Cystectomy is the most satisfactory method for eliminating the symptoms caused by cysts. As for congenital multiple liver cysts (congenital polycystic liver), since the cysts within the liver grow sequentially, resection of a single large liver cyst cannot maintain long-term efficacy. At this point, laparoscopic cyst fenestration and drainage can be the first choice to minimize surgical trauma.

　　1, Surgical methods for congenital liver cysts.

　　(1) Liver cyst resection:

　　① The indications for surgery are:

　　A, liver cysts with obvious clinical symptoms.

　　B, liver cysts located in the lower segment of the liver and superficial.

　　C, due to cyst compression, atrophy and fibrosis of liver lobes (commonly seen in the left liver lobe), the atrophied liver lobe along with the cyst can be resected, but lobectomy is not suitable for multiple liver cysts.

　　D, localized liver cysts with complications, such as intracystic hemorrhage, bile fistula, chronic infection, or suspected malignant transformation, should undergo cyst resection.

　　E, patients who can withstand major surgery.

　　② Contraindications for surgery include:

　　A, elderly patients with incomplete function of important organs.

　　B, multiple liver cysts or polycystic liver.

　　C, deep location of the cyst, close to the important structures near the hepatic hilum, extensive stripping area, abundant bleeding during separation of the cyst wall, technically challenging.

　　(2) Opening of liver cyst (opening of liver cyst): This surgical method was proposed by Lin TY, is simple, minimally invasive, and suitable for decompression and drainage of multiple liver cysts (polycystic liver) and simple solitary liver cysts without complications. Generally, the effect is good, but sometimes the recurrence of the cyst is caused by adhesion and obstruction of abdominal visceral organs at the opening site. The surgical method is to remove a piece of cyst wall and liver capsule that protrudes to the surface of the liver. There are two methods: laparotomy and laparoscopy.

　　① Indications for surgery:

　　A, giant cysts projecting towards the liver surface with obvious clinical symptoms.

　　B, clear diagnosis, no complications of the cyst.

　　C, deal with the cysts concurrently during other upper abdominal surgeries (most commonly cholecystectomy).

　　D. Patients who are suitable for surgery.

　　② Indications for surgery:

　　A. Liver cystic lesions caused by other reasons.

　　B. Communicating multiple liver cysts within the liver.

　　C. Liver cystic adenoma.

　　D. Liver cysts with complications.

　　E. Small asymptomatic cysts.

　　F. Cysts located deeply and not protruding into the liver surface.

　　II. Sclerosing therapy of liver cyst (sclerosing therapy of the liver cyst): Simple liver cysts are treated by injecting vascular sclerosing agents (commonly anhydrous ethanol 95% to 99.8%) into the cyst cavity to destroy the endothelium of the cyst. After one to several fluid aspirations and drug injections, the cyst cavity can gradually shrink, achieving good short-term effects. For smaller liver cysts (diameter

　　There are two methods of liver puncture sclerosis therapy: cyst injection and retention method and puncture and tube placement alcohol lavage method.

　　(1) Cyst injection and retention method: Under local anesthesia, ask the patient to hold their breath during the puncture, insert the needle into the cyst cavity under B-ultrasound guidance, withdraw the needle core, aspirate the cyst fluid, inject 10-20ml of 2% lidocaine into the cavity, and then inject anhydrous alcohol 2-3 minutes later. The injection amount should be 1/5 to 1/4 of the aspirated amount, with a maximum total of about 100ml. If the cyst fluid is too much, it can be treated in several sessions. Insert the needle core and hold the breath when withdrawing the needle to prevent the alcohol in the cavity from entering the abdominal cavity and causing a reaction. Rest in bed for 4 hours after the operation.

　　(2) Puncture, tube placement, and alcohol lavage method: After puncture, leave the catheter in the cyst cavity for continuous drainage. After the cyst fluid is emptied, wash the cyst wall with anhydrous alcohol, repeat until the cyst cavity closes and the catheter is removed. The advantage of this method is that it can avoid liver damage from alcohol and ensure complete closure of the cyst wall. The disadvantage is that the placement of the catheter causes inconvenience to the patient's life and may lead to infection. Regardless of the method, ultrasound-guided cyst sclerosis therapy has become the main method for treating liver cysts.

　　II. Prognosis

　　The disease progresses slowly and has a good prognosis. Solitary liver cysts can be cured by non-surgical or surgical treatment. Multicystic liver disease can alleviate symptoms after treatment, and it is helpful for the recovery of liver function and the improvement of overall condition. The disease generally does not cause liver function damage, but some advanced patients, due to severe destruction of liver tissue, may develop complications such as jaundice and ascites, which are difficult to treat with various methods; such patients have a poor prognosis, and if combined with polycystic kidney disease, they may die from liver and kidney failure.