Echinococcosis of the liver

There are two chronic echinococcal liver diseases: echinococcal cyst caused by Echinococcus granulosus larvae and alveolococcosis caused by Echinococcus multilocularis.

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How does liver echinococcosis develop?

The source of infection is dogs that eat the entrails of infected sheep and cows. Humans become infected when they eat food contaminated with helminth eggs that are excreted into the environment with the feces of dogs and wolves. Humans can also become infected by petting a dog. When an egg passes through the duodenum, a larva emerges from it, which penetrates the intestinal wall, and then it enters the liver with the bloodstream, where the larvae are most often retained.

A parasite that has settled in the liver can be destroyed under the influence of the host's defense mechanisms or slowly develop into cysts up to 20 cm in diameter or more.

The contents of echinococcal cysts are a transparent liquid in which daughter and granddaughter embryos - scolexes - float.

An echinococcal cyst has a formed capsule, and its growth occurs within the capsule due to compression of surrounding organs and tissues. In contrast, alveococcosis is characterized by invasive growth, as a result of which the node grows into neighboring organs.

Complications of echinococcosis are associated with the growth of the cyst and its compression of blood vessels and bile ducts. Rupture of the cyst is possible, with the contents leaking into the free abdominal cavity and bile ducts.

Alveococcosis is characterized by small white or white-yellow bubbles embedded in inflammatory and necrotic surrounding tissue. The bubbles are tightly fixed to the surrounding tissue, and their isolated enucleation is impossible. The size of individual bubbles does not exceed 3-5 mm, but their clusters can form nodes up to 15 cm or more in diameter. Alveococcosis is characterized by infiltrating growth and reproduction of parasite bubbles by the type of external budding. As a result, long-existing nodes have a bumpy shape, they are dense to the touch, so a malignant tumor is sometimes mistakenly diagnosed.

Multiple alveolar echinococcosis invasion may simulate metastatic liver tumors.

Large alveococcal nodes are subject to necrotic decay; starting in the center of the node and leading to the formation of one or more cavities, often containing sequesters of necrotic tissue.

Due to invasive growth, alveolar nodes grow into blood vessels and bile ducts, and when located near the surface of the liver, into neighboring organs (stomach, gallbladder, diaphragm, adrenal gland, spine), which further increases their similarity to a malignant tumor.

Symptoms of liver echinococcosis

In liver echinococcosis, symptoms of the disease appear only with a significant increase in the size of the cyst and compression of adjacent organs, primarily large vessels (including the portal vein), and disruption of blood flow in them. In some cases, a long asymptomatic course is noted. In others, the general condition quickly worsens.

There are three stages (periods). The first stage is from the parasite invasion to the appearance of the first symptoms. The second stage is from the appearance of the first complaints to the onset of complications of echinococcosis. The third stage includes manifestations of complications of the echinococcal cyst. The first stage of the disease is asymptomatic. In the second stage, weakness develops, appetite worsens, and weight loss occurs. Dull pains, a feeling of heaviness, and pressure in the right hypochondrium appear. Allergic reactions in the form of urticaria, diarrhea, and vomiting occur. Uncomplicated liver echinococcosis has a fairly favorable prognosis.

However, there is a risk of complications (stage three). The cyst may become purulent, perforate into a cavity or organ, or develop severe allergic reactions to echinococcus antigens.

Serious complications include ruptures of cysts into the abdominal and pleural cavities. A rupture of a cyst into the bile ducts is not as dangerous, as it can be drained. In addition, secondary infection of cysts is possible.

If the cyst compresses the intra- or extrahepatic bile ducts, jaundice may occur. If the cyst suppurates, pain in the right hypochondrium increases, intoxication progresses, and body temperature rises to 40-41 °C.

It is possible for the abscess to break through into the pleural cavity, as well as into the retroperitoneal space. Sometimes the cyst can empty into one of the neighboring organs - the stomach, intestine, bronchi, gallbladder, intrahepatic bile ducts.

Most often, echinococcal cysts are located in the right lobe of the liver, on its anterior-inferior or posterior-inferior surface. Dissemination of the process and the formation of daughter bubbles can be accompanied by severe damage to the abdominal cavity.

Echinococcosis of the liver can also lead to death, but with the use of antibiotics the prognosis becomes more favorable.

In patients with alveococcosis, the progression of the disease is manifested by jaundice, enlargement of the spleen, and in some cases, ascites. The node may disintegrate with the formation of a cavity; in 20% of cases, nodes with multiple localizations grow into other organs.

Alveolococcosis is similar in its course to a local malignant tumor.

Diagnosis of liver echinococcosis

The diagnosis of liver echinococcosis is made on the basis of:

• indications in the anamnesis of staying in an area endemic for echinococcosis;
• detection by palpation of a dense elastic cyst associated with the liver;
• positive serological reactions (latex agglutination reaction, passive hemagglutination, etc.);
• detection of a pathological focus in the projection of the liver based on the results of ultrasound, computed tomography, and angiography of the liver vessels.

Alveococcosis is characterized by the same criteria, but palpation does not reveal a dense elastic cyst associated with the liver. The palpable alveococcal node has a stony density, its borders are unclear, gradually passing into the healthy liver parenchyma.

Serological studies allow to detect antibodies to echinococcus antigens. Currently, serological reactions are used: latex agglutination (RIA), double diffusion in gel, indirect hemagglutination, immunofluorescence (IFR), ELISA.

Radiographic changes include high position and limited mobility of the diaphragm, hepagomegaly, calcification of ectocysts, which appears on the radiograph as a rounded darkening.

Ultrasound or CT reveals single or multiple cysts, which can be single- or multi-chambered, thin- or thick-walled. MRI reveals a characteristic intense outline, daughter cysts, and stratification of the cyst membranes. ERCP reveals bile duct cysts.

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Treatment of liver echinococcosis

Surgical treatment of liver echinococcosis is the main method. There are no effective conservative measures to combat the parasite that has invaded. In addition, the death of the echinococcus is not a cure for the patient. As a rule, various complications arise in this phase: suppuration, perforation or hemorrhage in the echinococcal cyst, etc.

The risk of rupture and secondary infection of cysts in echinococcosis is so great that if there are few of them, they are large in size and the patient’s condition allows it, surgical treatment is necessary.

Mebendazole or albendazole can be used as drug treatment. However, they are not effective enough in case of large liver cysts; relapses of the disease are possible.

Antibiotic therapy for alveococcosis is effective, but does not cure it completely. Without complete surgical removal of the affected tissue, the disease is fatal. Alveococcosis may require liver transplantation.