Hydatid Cysts Treatment & Management

Inpatient care for individuals who have had surgical resection of their hydatid cyst(s) is similar to that for any other surgical procedure on the affected organ.

Special consideration must be made for patients with hepatic cystic echinococcosis (CE) who were found to have biliary communication. These patients must be observed for signs and symptoms of either biliary obstruction or fistula formation. If either of these complications occurs, the patient must be treated by percutaneous or endoscopic stenting of the biliary tree with or without sphincteroplasty.

Postoperatively, treatment with benzimidazoles is continued for approximately 1 month, although the exact duration has not been determined.

Antibiotics are used prophylactically for surgery as indicated in patients with a cystobiliary fistula, for the treatment of infected cysts, and for the treatment of associated infections. Benzimidazoles are continued after discharge.

Transfer

Several criteria must be met in medical centers in order for patients to be treated appropriately. The lack of any of the following criteria should lead to patient transfer:

• Medical staff experienced in the treatment of echinococcosis (eg, surgeons, radiologists, infectious disease consultants)

• Medical centers that are able to provide the services for treatment (eg, well-equipped intensive care unit and surgical ward, well-equipped operating room, diagnostic radiology and laboratory facilities)

• Availability of scolicidal agents

Medical management differs for cystic echinococcosis (CE) and alveolar echinococcosis (AE). In CE, surgery remains the primary treatment and the only hope for complete cure. Better forms of chemotherapy and newer methods, such as the puncture, aspiration, injection, and reaspiration (PAIR) technique are now available but need to be tested. Currently, indications for these modes of therapy are restricted. In AE, radical surgical excision is coupled with chemotherapy in operable cases and long-term aggressive chemotherapy for partially resected or unresectable lesions. In CE, one should consider the risks and benefits, indications, and contraindications for each case before making a decision regarding the type and timing of surgery.

Chemotherapy in CE

Chemotherapy is indicated in patients with primary liver or lung cysts that are inoperable (because of location or medical condition), patients with cysts in two or more organs, and peritoneal cysts.

Contraindications include early pregnancy, bone marrow suppression, chronic hepatic disease, large cysts with the risk of rupture, and inactive or calcified cysts are contraindications. A relative contraindication is bone cysts because of the significantly decreased response.

Chemotherapeutic options include two benzimidazoles, albendazole and mebendazole. Albendazole is administered in several 1-month oral doses (10-15 mg/kg/d) separated by 14-day intervals. New data for continuous treatment are emerging from China. The optimal period of treatment ranges from 3-6 months, with no further increase in the incidence of adverse effects if this period is prolonged. Mebendazole is also administered for 3-6 months orally in dosages of 40-50 mg/kg/d. Limited data are available on the weekly use of praziquantel, an isoquinoline derivative, at a dose of 40 mg/kg/wk, especially in cases in which intraoperative spillage has occurred. Albendazole has been found ineffective in the treatment of primary liver cysts in patients who are surgical candidates. ^[14]

Monitor patients for adverse effects of agents every 2 weeks with a complete blood cell (CBC) count and liver enzyme evaluation for the first 3 months and then every 4 weeks. Monitoring albendazole and mebendazole serum levels is desirable, but few laboratories are capable of performing this measurement. Imaging studies are required for follow-up on the morphologic status of the cyst.

Response rates in 1000 treated patients showed that 30% had cyst disappearance (cure), 30-50% had a decrease in the size of the cyst (improvement), and 20-40% had no changes. Younger adults responded better than older adults.

Chemotherapy in AE

Chemotherapy with benzimidazoles is used perioperatively for approximately 2 years in patients in whom radical resection is feasible because of possible undetected residual parasite tissue. In patients who undergo a partial resection, patients who are inoperable, or patients who have had a liver transplant, long-term chemotherapy is required (3-10 y).

Because chemotherapy is the only treatment in certain cases, contraindications are limited to early pregnancy and severe leukopenia. Chemotherapeutic agents and patient monitoring are the same as with CE, but the length of treatment is different.

A significant increase in the 10-year survival rates exists in patients receiving chemotherapy compared to patients who are not treated (85-90% vs 10%, respectively).

PAIR in CE

The PAIR technique is performed using either ultrasound or computed tomography (CT) guidance, involves aspiration of the cyst contents via a special cannula, followed by injection of a scolicidal agent for at least 15 minutes, and then reaspiration of the cystic contents. This is repeated until the return is clear. The cyst is then filled with isotonic sodium chloride solution. Perioperative treatment with a benzimidazole is mandatory (4 d prior to the procedure and for 1-3 mo after).

The PAIR technique can be performed on liver, bone, and kidney cysts but should not be performed on lung and brain cysts. The cysts should be larger than 5 cm in diameter and type I or II according to the Gharbi ultrasound classification of liver cysts (ie, type I is purely cystic; type II is purely cystic plus hydatid sand; type III has the membrane undulating in the cystic cavity; and type IV has peripheral or diffuse distribution of coarse echoes in a complex and heterogeneous mass). PAIR can be performed on type III cysts as long as it is not a honeycomb cyst.

Inoperable patients; patients refusing surgery; patients with multiple cysts in segment I, II, and III of the liver; and relapse after surgery or chemotherapy are indications for the PAIR technique.

Early pregnancy, lung and brain cysts, inaccessible cysts, superficially located cysts (risk of spillage), type II honeycomb cysts, type IV cysts, and cysts communicating with the biliary tree (risk of sclerosing cholangitis from the scolecoidal agent) are contraindications for the PAIR technique.

The reduced cost and shorter hospital stay associated with PAIR compared to surgery make it a desirable option. The risk of spillage and anaphylaxis is considerable, especially in superficially located cysts, and transhepatic puncture is recommended. Sclerosing cholangitis (chemical) and biliary fistulas are other risks. Experience is still limited, but early reports are supportive of this technique if the indications are followed.

Interventional procedures in AE

Patients with AE require interventional procedures when radical complete resective surgery is not possible. Local complications may occur. These interfere with the function of the organ and may be alleviated by certain interventional procedures. These procedures can be performed endoscopically or under ultrasound or CT guidance. Dilatation, stenting, drainage of collections, and sclerosis of esophageal varices are some examples.

Indications include hyperbilirubinemia, vena cava thrombosis, portal vein thrombosis, necrotic collections, and bleeding esophageal varices.

Contraindications include cases in which postinterventional chemotherapy is not possible and the risk of spreading the parasite is high.

Studies have shown that laparoscopic therapy and puncture, aspiration, injection, and reaspiration (PAIR) intervention to be safe and effective alternative options to open surgery in patients with a suitable indication such as cyst type and location. ^{[15, 16, 17, 18]} The indications and type of surgery are different for cystic echinococcosis (CE) and alveolar echinococcosis (AE).

Cystic echinococcosis

Approach considerations

Large liver cysts with multiple daughter cysts; superficially located single liver cysts that may rupture (traumatically or spontaneously); liver cysts with biliary tree communication or pressure effects on vital organs or structures; infected cysts; and cysts in lungs, brain, kidneys, eyes, bones, and all other organs are indications for surgery.

General contraindications to surgical procedures (eg, extremes of age, pregnancy, severe preexisting medical conditions); multiple cysts in multiple organs; cysts that are difficult to access; dead cysts; calcified cysts; and very small cysts are contraindications.

Surgical options include radical surgery (total pericystectomy or partial affected organ resection, if possible), conservative surgery (open cystectomy), or simple tube drainage of infected and communicating cysts. The more radical the procedure, the lower the risk of relapses but the higher the risk of complications. Patient care must be individualized accordingly.

Laparoscopic approach has gained more acceptance and popularity in recent years. ^[19]

The medical staff at the treating center should have experience with treating CE. Concomitant treatment with benzimidazoles (albendazole or mebendazole) has been reported to reduce the risk of secondary echinococcosis. Treatment is started 4 days preoperatively and lasts for 1 month.

Description of surgical procedure

The basic steps of the procedure are eradication of the parasite by mechanical removal, sterilization of the cyst cavity by injection of a scolicidal agent, and protection of the surrounding tissues and cavities.

Scolicidal agents include formalin, hydrogen peroxide, hypertonic saline, chlorhexidine, absolute alcohol, and cetrimide. A variety of complications have been described with all scolicidal agents, but in the authors' experience, 0.5% cetrimide solution provides the best protection with the least complications. Other scolicidal agents are 70-95% ethanol and 15-20% hypertonic saline solutions. A report by Ochieng'-Mitula and Burt in 1996 on the injection of ivermectin in the hydatid cysts of infected gerbils revealed several damaged cysts with no viable protoscoleces. ^[20] Further evaluation of this scolicidal agent is needed.

At surgery, the exact location of the cyst is identified and correlated with the radiologic findings. The surrounding tissues are protected by covering them with cetrimide-soaked pads. The cyst is then evacuated using a strong suction device, and cetrimide is injected into the cavity. This procedure is repeated until the return is completely clear. Cetrimide is instilled and allowed to sit for 10 minutes, after which it is evacuated, and the cavity is irrigated with isotonic sodium chloride solution. This ensures both mechanical and chemical evacuation and destruction of all cyst contents. During this process, care is taken to ensure no spillage occurs to prevent seeding and secondary infestation.

The cavity is then filled with isotonic sodium chloride solution and closed. Rarely, the omentum is needed to fill the cavity. The cyst fluid is inspected for bile staining at the end of the evacuation and irrigation process. The inside of the cyst is inspected, and any bile duct communication is sutured. In case of infected cysts with biliary communication, closed suction drainage is required. Regardless of whether an open or a laparoscopic approach is chosen, these basic principles must be followed in order to ensure the safety of the procedure.

Alveolar echinococcosis

Approach considerations

Surgical intervention is indicated if the liver lesion is resectabale (assessed by imaging techniques preoperatively).

Contraindications include inoperable lesions, extensive lesions, and lesions extending outside the liver and involving other organs.

Radical surgery with complete excision of the lesion is the only chance for cure. In certain cases, total hepatectomy with transplantation has been performed as long as no extra hepatic disease is present. Reemergence of the parasite in the transplanted liver and distant metastasis occur under immunosuppression. Partial resections of unresectable masses are considered to decrease the parasite load to aid the chemotherapeutic agents. ^[21] More recently, ex vivo liver resection combined with autotransplantation appears to show potential for curing end-stage hepatic alveolar echinococcosis in those with unresectable lesions. ^[22]

Surgical staff experienced in major liver resections and medical staff experienced in the administration of chemotherapy to persons with AE are required. Perform liver transplantations in centers where a well-coordinated and experienced team is available.

Consultants are needed in different contexts to help in the management of cystic echinococcosis (CE) and alveolar echinococcosis (AE).

Although an infectious disease consultant is needed to help in the administration and monitoring of chemotherapeutic agents, the interventional radiologist has different roles in CE and AE.

In certain cases of CE, the puncture, aspiration, injection, and reaspiration (PAIR) procedure is needed. In certain instances involving AE, interventions are required to improve organ function.

Because human infection with Echinococcus results from fecal-oral contamination, prevention requires the following steps:

• Education on proper hygiene

• Proper cleansing of uncooked food and avoidance when possible

• Dietary regulation of pet dogs (stop the habit of feeding viscera of intermediate hosts, such as sheep, to pet dogs)

• Regulate pet dog activity to prevent ingestion of sheep material

• Avoidance of unregulated dogs

• Treatment of pet dogs in endemic areas for intestinal echinococcosis with praziquantel (5 mg/kg) periodically

• Control of the dog population

• Regulation of livestock butchering

Outpatient care is directed towards the following end points:

• Chemotherapy: Postoperative treatment with benzimidazoles is continued for 1 month in patients with cystic echinococcosis (CE) who have successfully undergone complete resection or puncture, aspiration, injection, and reaspiration (PAIR). The treatment is continued for 3-6 months for patients with resected alveolar echinococcosis (AE), incompletely resected CE, spillage during surgery or PAIR, and metastatic lesions. Chemotherapy is needed for 3-10 years for patients with partially resected AE, unresectable AE, or liver transplant for AE.

• Laboratory tests: Patients on benzimidazoles should have a complete blood cell (CBC) count and liver enzyme evaluation performed at biweekly intervals for 3 months and then every 4 weeks to monitor for toxicity. Enzyme-linked immunosorbent assay (ELISA) or indirect hemagglutination tests are usually performed at 3-, 6-, 12-, and 24-month intervals to assess for recurrence of resected disease or aggravation of an existing disease.

• Imaging: Ultrasonography and/or computed tomography (CT) scanning are used in follow-up at the same intervals as the laboratory tests or as clinically indicated.