eMedicine Specialties > Gastroenterology > Liver

Hydatid Cysts: Treatment & Medication

Author: Imad S Dandan, MD, Consulting Surgeon, Department of Surgery, Trauma Section, Scripps Memorial Hospital
Coauthor(s): Assaad M Soweid, MD, Assistant Professor, Department of Internal Medicine, American University of Beirut, Lebanon; Firass Abiad, MD, Head of Division, General and Laparoscopic Surgery, Specialized Medical Center Hospital, Saudi Arabia
Contributor Information and Disclosures

Updated: Jun 17, 2008

Treatment

Medical Care

Medical management differs for CE and 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, consider risks and benefits, indications, and contraindications for each case before making a decision regarding the type and timing of surgery.

• Chemotherapy in CE
  • Indications: Chemotherapy is indicated in patients with primary liver or lung cysts that are inoperable (because of location or medical condition), patients with cysts in 2 or more organs, and peritoneal cysts.
  • Contraindications: 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 agents: Two benzimidazoles are used, 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.¹
  • Monitoring: Monitor patients for adverse effects of agents every 2 weeks with a 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.
  • Outcome from medical treatment of CE: Response rates in 1000 treated patients were that 30% had cyst disappearance (cure), 30-50% had a decrease in the size of the cyst (improvement), and 20-40% had no changes. Also, younger adults responded better than older adults.
• Chemotherapy in AE
  • Indications: 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).
  • Contraindications: Because chemotherapy is the only treatment in certain cases, contraindications are limited to early pregnancy and severe leukopenia. Chemotherapeutic agents and monitoring are the same as with CE, but the length of treatment changes.
  • Outcome: A significant increase in 10-year survival rates exists in patients receiving chemotherapy compared to patients who are not (85-90% vs 10%, respectively).
• PAIR in CE: This technique, performed using either ultrasound or CT guidance, involves aspiration of the 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 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 is the 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.
  • Indications: Inoperable patients; patients refusing surgery; multiple cysts in segment I, II, and III of the liver; and relapse after surgery or chemotherapy are indications for the PAIR technique.
  • Contraindications: Early pregnancy, lung 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.
  • Outcome: The reduced cost and shorter hospital stay associated with PAIR compared to surgery make it desirable. 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: These include hyperbilirubinemia, vena cava thrombosis, portal vein thrombosis, necrotic collections, and bleeding esophageal varices.
  • Contraindications: Postinterventional chemotherapy is not possible, and the risk of spreading the parasite is high.

Surgical Care

The indications and type of surgery are different for CE and AE.

• Cystic echinococcosis
  • Indications: 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.
  • Contraindications: 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.
  • Choice of surgical technique: Radical surgery (total pericystectomy or partial affected organ resection, if possible), conservative surgery (open cystectomy), or simple tube drainage for infected and communicating cysts are choices for surgical technique. The more radical the procedure, the lower the risk of relapses but the higher the risk of complications. Patient care must be individualized accordingly.
  • 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 severely damaged cysts with no viable protoscoleces.² Further evaluation of this scolicidal agent is needed.
    • At surgery, the exact location of the cyst is identified and correlated to 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, omentum is needed to fill the cavity. In the case of hepatic cysts, the fluid is inspected for bile staining and 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 laparoscopic approach is chosen, these basic principles must be followed in order to ensure the safety of the procedure.
  • Medical requirements: 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.
• Alveolar echinococcosis
  • Indications: The indication is resectability of the liver lesion (assessed by imaging techniques preoperatively).
  • Contraindications: These are inoperable lesions, extensive lesions, and lesions extending outside the liver and involving other organs.
  • Choice of surgical technique: 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.
  • Medical requirements: 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.

Consultations

Consultants are needed in different contexts to help in the management of CE and 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 PAIR procedure is needed.
• In certain instances involving AE, interventions are required to improve organ function.

Medication

Drug therapy for echinococcosis is limited. The anthelmintic benzimidazoles, namely albendazole and mebendazole, are used for treatment and prophylaxis. Praziquantel, an isoquinoline derivative, is used as an adjunct for therapy.

Anthelmintics

Treatment of Echinococcus infestation as a primary modality or adjunct to surgery.

Albendazole (Albenza)

Decreases ATP production in worm, causing energy depletion, immobilization, and, finally, death. Orally administered broad-spectrum anthelmintic with poor aqueous solubility. Poorly absorbed from GI tract but metabolized quickly to albendazole sulfoxide, which is easily absorbed. Systemic activity is attributed to first metabolite. Plasma level is noted to rise significantly (as much as 5-fold) when ingested after high-fat meal. Experience with patients <6 y is limited.

Mebendazole (Vermox)

Causes worm death by selectively and irreversibly blocking uptake of glucose and other nutrients in susceptible adult intestine where helminths dwell. Broad-spectrum synthetic anthelmintic. Metabolites are devoid of anthelmintic activity.

Trematodicides

Used to potentiate effect of benzimidazoles during therapy.

Praziquantel (Biltricide)

Increases cell membrane permeability in susceptible worms, resulting in loss of intracellular calcium, massive contractions, and paralysis of musculature. In addition, produces vacuolization and disintegration of schistosome tegument. This is followed by attachment of phagocytes to parasite and death. Isoquinoline derivative that is easily absorbed through GI tract.

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