Management of Hydatid Disease

See also our article on Hydatid Disease.

• Treatment differs for cystic echinococcosis (CE) and alveolar echinococcosis (AE).
• Surgery remains the mainstay of treatment, with less invasive methods and combinations with chemotherapy coming to the fore as techniques develop.
• In CE, risks vs benefits, indications, and contraindications for each individual must be considered before deciding on type and timing of surgery.
• In AE, more radical surgical excision is coupled with chemotherapy in operable cases, but if the cyst can only be partially resected, or is inoperable, long-term aggressive chemotherapy is employed.

Chemotherapy^1-2

• This is indicated as an adjunct to surgery, in patients with inoperable lung or liver cysts (due to site of cyst or patients too ill for surgery), patients with cysts in two or more organs, and peritoneal cysts.
• Two drugs are available, both from the benzimidazole group, albendazole and mebendazole.
  • Albendazole appears to have better absorption and better clinical results than mebendazole. It is taken together with a fat-containing meal twice daily (manufacturer's recommendation, 10-15 mg/kg/day). The drug is licensed for cyclical treatment only (i.e. 28 days of treatment followed by 14 days of interruption), but trials using continuous long-term treatment do not show any adverse effects.
  • Mebendazole is taken with a fat-containing meal three times daily, recommended daily dosage 40-50 mg/kg/day. If used alone, chemotherapy is usually required for months or years.
• Contraindications:
  • Early pregnancy
  • Bone marrow suppression
  • Chronic hepatic disease
  • Large cysts with the risk of rupture
  • Inactive or calcified cysts
  • A relative contraindication is bone cysts because of the significantly decreased response
• Most frequent adverse effects of benzimadoles:
  • Gastrointestinal disturbances
  • Reversible alopecia
  • Elevation of serum transaminases
  • Proteinuria
  • Neurological symptoms
  • Neutropenia
• Significant interactions:
  • Carbamazapine (may decrease efficacy)
  • Dexamethasone and cimetidine (may increase toxicity)
• Monitoring
  • Full blood count and liver function tests should be performed every 2 weeks.
  • The patient should be advised to report adverse effects.
  • Drug level monitoring is ideal, but few laboratories provide this service.
  • Imaging of the cyst is required to follow up morphological resolution.
• Newer drugs such as praziquantel are being evaluated. Trials suggest that a combination of praziquantel with albendazole is more effective than albendazole alone.
• Outcome - one study of 1000 patients showed 30% cure rate (as measured by disappearance of cyst), 3-50% had decrease size of cyst, 20-40% no change. The younger the patient, the better the outcome.

Interventional procedures^1,3-4

PAIR (Puncture, Aspiration, Injection, Re-aspiration) is an effective and safe treatment.

• Indications:
  • Cysts not suitable for conventional surgery
  • Multiple cysts in segment I, II, and III of the liver (as described in the Couinaud Liver classification).⁵
  • Cysts should be larger than 5 cm in diameter and either Gharbi type I or II, or type III if not a honeycomb cyst .
  • Gharbi classification:
    • Type I - purely cystic
    • Type II- purely cystic plus hydatid sand
    • Type III - membrane undulating in the cystic cavity
    • Type IV - peripheral or diffuse distribution of coarse echoes in a complex and heterogeneous mass
  • Patients refusing conventional surgery
  • Relapse after surgery or chemotherapy
• Aspiration and re-aspiration are repeated until the aspirate is clear, and the cyst is then filled with isotonic sodium chloride.
• Cover with a benzimidazole in imperative (4 days prior and 1-3 months after the procedure).
• The technique can be performed on liver, bone, and kidney cysts but should not be performed on lung and brain cysts.
• Transhepatic puncture is recommended for superficially located cysts.
• 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 scolecidal agent)
• Complications
  • Spillage of cyst contents
  • Anaphylaxis reactions
  • Sclerosing cholangitis (chemical)
  • Biliary fistulas
• Outcome:
  • One meta-analysis demonstrated greater clinical and parasitological efficacy in patients treated with PAIR plus chemotherapy than those undergoing radical surgery such as cystectomy or partial organ resection.
  • The PAIR group also had lower rates of morbidity, mortality, disease recurrence, and shorter hospital stays.

Conventional surgery

• Indications
  • Large liver cysts with numerous daughter cysts
  • Liver cysts with communication to biliary tree or pressing on surrounding structures
  • Superficially located single liver cysts
  • Likely to rupture Infected cysts
  • Cysts in lungs, brain, kidneys, eyes, bones
• Contraindications:
  • Pregnancy
  • Medically unsuitable for surgery
  • Multiple cysts in multiple organs
  • Inaccessible cysts
  • Cysts that are inactive, calcified or very small
• Choice of technique - must be individualised for each patient. Options include:
  • Radical surgery (total pericystectomy or partial affected organ resection, if possible)
  • Conservative surgery (open cystectomy)
  • Simple tube drainage for infected and communicating cysts.
• The more radical the procedure, the lower the risk of relapses but the higher the risk of complications.
• Basic steps:
  • Protection of surrounding tissue with cetrimide-soaked pads
  • Suction evacuation of cyst
  • Sterilisation of the cyst cavity by injection of a scolecidal agent
  • Avoid spillage which might cause seeding and secondary infestation
  • Hepatic cysts: evidence sought for bile duct communication - if present it should be sutured
• Concomitant treatment with benzimidazoles reduces risk of secondary echinococcosis (start 4 days pre-op, continue for one month)

Chemotherapy^1-2,6

• Treatment with benzimadoles is indicated for:
  • 2 years perioperatively for patients considered for radical resection in order to combat undetected infected tissue
  • Long-term therapy (3-10 years) for patients who have partial resection
  • Inoperable conditions
  • Liver transplants.
• Contraindications - if chemotherapy is the only available option, the risks outweigh benefits for all but early pregnancy and severe leukopenia.
• Drug choices and monitoring are as for CE, but the duration of treatment is different (see above).
• 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).

Interventional procedures^1,3-4

Minimally Invasive

• Indications: this is useful when radical resective surgery is not possible. e.g.
  • Hyperbilirubinemia
  • Vena cava thrombosis
  • Portal vein thrombosis
  • Necrotic collections
  • Bleeding oesophageal varices
• Examples of minimally invasive procedures done under ultrasound or CT guidance include:
  • Dilatation
  • Stenting
  • Drainage
  • Sclerosis of oesophageal varices
• Contraindicated if postinterventional chemotherapy not possible, as risk of spreading the parasite is high.

Conventional surgery

• Indications - resectable liver lesion as assessed by imaging
• Contraindications - inoperable lesions, extensive lesions, lesions involving other organs
• Options:
  • The only curative procedure is radical surgery with complete excision of the lesion .
  • Total hepatectomy with transplantation is warranted in some cases if no extra hepatic disease present.
• Reemergence of the parasite in the transplanted liver and distant metastasis may occur under immunosuppression.
• Partial resections of unresectable masses decrease the parasite load and may aid chemotherapy.