bubble_chart Overview

Hepatic hydatid cysts are commonly found in pastoral areas. In regions such as South America, Southern Europe, and Australia, they are associated with sheep herding, while in Iran and Iraq, they are linked to camels. In Canada and Alaska, the condition may be related to reindeer. In China, it is more prevalent in Inner Mongolia, the northwest, western Sichuan, Tibet, and other areas. This disease, also known as hepatic echinococcosis, is caused by the larvae of Echinococcus granulosus invading the liver.

bubble_chart Etiology

Human hepatic hydatid cysts are the asexual stage of *Echinococcus granulosus* with humans as intermediate hosts. The primary hosts of this tapeworm are dogs, foxes, or wolves, while the intermediate hosts include sheep, cattle, horses, pigs, and humans. This parasite attaches to the villi of the dog's small intestine, where adult worms continuously release hexacanth larvae protected by shells. These larvae are excreted in feces and adhere to dog or sheep fur. Humans or other intermediate hosts become infected by ingesting contaminated water or food. After digestion in the stomach or upper small intestine, the hexacanth larvae shed their shells, penetrate the gastrointestinal wall, and enter the portal vein, mostly lodging in the liver, with a few migrating to the lungs and other organs. The hydatid cysts initially form in the affected organs, with the cyst wall becoming the inner capsule, while the host tissue forms a fibrous outer membrane around it, known as the outer capsule. The inner capsule consists of two layers: the outer laminated membrane and the inner germinal layer. The germinal layer produces brood capsules, protoscoleces, daughter cysts, and granddaughter cysts. When dogs, foxes, or wolves consume the infected organs of sheep, cattle, or other intermediate hosts, the parasite completes its life cycle.

bubble_chart Clinical Manifestations

The clinical manifestations are often nonspecific and are more common in young and middle-aged individuals. In the initial stage (first stage), there may be no symptoms. As the cyst enlarges, an upper abdominal mass, abdominal distension and fullness, and abdominal pain may be palpable. If located in the right upper lobe of the liver, it may elevate the diaphragm, leading to respiratory symptoms. Many patients have experienced allergic reaction symptoms. A few may develop jaundice due to cyst compression of the bile ducts. Some may also present with cholangitis or even sepsis due to secondary infection or rupture into the bile ducts. Rupture into the thoracic cavity may cause respiratory symptoms or bronchobiliary fistula. The main sign is a cystic mass in the upper abdomen; if located in the upper part of the liver, only hepatomegaly may be observed. Corresponding signs may appear in cases with complications.

bubble_chart Treatment Measures

1. For small and deeply embedded hepatic hydatid cysts, close follow-up with regular ultrasound examinations is recommended. If the cyst enlarges to near the liver surface, surgical treatment can be considered.

2. Endocystectomy is the most commonly used surgical procedure, with the following key points: ① When exposing the hydatid cyst, carefully protect the wound and surrounding organs to avoid contamination by cyst fluid, scolex implantation, and allergic reactions. ② Before incising the cyst cavity, gradually decompress it. Aspiration of cyst fluid can also help determine whether infection or biliary fistula is present. ③ To kill the scolex, traditional methods involve injecting 10% formaldehyde solution or 3% hydrogen peroxide after decompression, followed by further aspiration of cyst fluid after 5 minutes. However, some argue that this method does not guarantee scolex eradication, as dilution of the cyst fluid reduces the efficacy of the medication. There have been reports of acute formaldehyde poisoning or late-stage biliary tract inflammation complications. Additionally, this method is ineffective for multiple cysts. ④ Before incising the outer cyst, further aspirate the cyst fluid to separate the inner and outer cysts. Ensure the suction device is unobstructed; using 2–3 suction devices may be necessary for large, high-tension cysts. Then, incise the outer cyst and remove the inner cyst, followed by wiping the inner wall of the outer cyst with hydrogen peroxide or diluted formaldehyde solution and cleaning it with saline gauze. ⑤ To eliminate the residual cavity, the outer cyst wall can be inverted and sutured, or a pedicled omentum can be used for packing. However, before managing the residual cavity, carefully check for biliary fistulas and close them if present.

3. For cases with concurrent infection, drainage is required. Liver resection is rarely performed and is only suitable for specific cases, such as those with thick, calcified cyst walls where the inner cyst is difficult to remove, multiple hydatid cysts confined to one lobe, or cases where the residual cavity or sinus is unlikely to heal after drainage.

bubble_chart Prognosis

The surgical mortality rate for hepatic hydatid cyst treatment ranges from 1.8% to 9%, generally between 2% and 4%. The postoperative recurrence rate varies from 5% to 12%, often due to small, deeply embedded cysts or the seeding of scoleces during the initial surgery.

bubble_chart Complications

Puncture should not be performed in cases suspected to be hepatic hydatid cysts to prevent cyst fluid leakage, which may lead to allergies, anaphylactic shock, or the entry of scoleces into the abdominal cavity causing secondary hydatid cysts.

bubble_chart Differentiation

① Congenital liver cyst: No history of living in pastoral areas, ultrasound shows extremely thin and clear cyst wall, hydatid skin test negative. ② Liver abscess: No history of living in pastoral areas but often has a history of dysentery or suppurative diseases, ultrasound shows unclear boundaries of the liquid occupying lesion, clinical history or manifestations of inflammation, hydatid skin test negative. However, infected hydatid liver cysts can easily be confused with it, and the hydatid skin test is the main basis for differentiation.