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Holzheimer RG, Mannick JA, editors. Surgical Treatment: Evidence-Based and Problem-Oriented. Munich: Zuckschwerdt; 2001.

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Surgical Treatment: Evidence-Based and Problem-Oriented.

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Hydatid liver disease

, M.D. and , M.D.

The University of New South Wales, St George Hospital, Kogarah, Sydney, Australia

Biology and epidemiology

Hydatidosis, a zoonotic infection, is due to the larval stage of the tapeworm Echinococcus (E.). Two of the recognised species, E. granulosus and E. multilocularis, are of importance for humans. Infection is acquired through ingestion of parasite eggs released in faeces of the definite host (a carnivore or a rodent) bearing the adult worm in its gut. Once ingested by the intermediate host (usually herbivore, occasionally rodent, accidentally human), the eggs hatch and migrate to a broad category of tissues to form multilayered metacestode cysts (primary echinococcosis) where the adult stage develops in the form of protoscoleces. The outmost layer of a cyst, the ectocyst or pericyst, is formed by compressed and fibrotic host tissue and may become calcified, whereas inner layers are of parasitic origin and act as a germinal centre. A cyst may or may not contain daughter cyst(s). Secondary echinococcosis can develop in the same or other organs.

The disease has a world-wide distribution. It is endemic in the Mediterranean and Baltic areas, Middle and Far East, South America and South Africa. Sheep-rearing European regions and central North America are also affected. E. granulosus producing unilocular hydatid disease (cystic echinococcosis - CE) is cosmopolitan whereas E. multilocularis producing alveolar hydatid disease (alveolar echinococcosis - AE) is limited to restricted areas of the northern hemisphere. Although less common, AE poses a far more serious problem due to the infiltrative nature of its cysts and its greater ability to metastasise; it has to be regarded as a malignant disease carrying a mortality of up to 90% in untreated cases. Unless otherwise stated in text we refer to E. granulosus and CE.

Diagnosis

Clinical features

Most patients will have a single organ involvement in primary echinococcosis. In adults the liver represents the prevalent site (50–70%) and lungs are the second commonest site (10–30%). In children the lungs are the prevalent location. Although primary extra-hepatic locations are less common (or even rare in AE), any other organ may be involved. After an asymptomatic phase of variable length, clinical manifestations depending on cysts localization and size appear as a result of compression or complication (rupture or infection). Cyst rupture can result in dissemination and hypersensitivity or anaphylactic reaction. Rupture into the biliary tree is the commonest complication (up to 25% of cases) and can be associated with biliary obstruction by daughter cysts. There is no specific clinical peculiarity for the disease although right upper quadrant pain, liver enlargement or a palpable mass with weight loss, fever or jaundice in endemic areas are strongly suggestive of hydatidosis.

Serological techniques

Biological diagnosis relies on serological tests. Complement fixation test has poor sensitivity and specificity. Indirect hemagglutination (IHA) has good sensitivity but false positives do occur. Immunoelectrophoresis (IE), especially if arc 5 is present (precipitation for antigen (Ag) 5), and enzyme-linked immunosorbent assay (ELISA) for IgG against Ag 5 or Ag B yield the best results. Their association may detect up to 90% and 80% of hepatic and pulmonary locations respectively. Immunodiagnostic tests been studied and reviewed extensively by Gottstein B. and Schantz P. Co-agglutination for circulating antigen and latex agglutination are well suited for diagnosis in field conditions (1). Hydatid antigen dot immunobinding assay (2) and dot-ELISA are aimed at the same use.

Serological tests such IHA and IE for the diagnosis of AE have used E. granulosus antigens for long. At present, more specific tests such as Emc- or Em2-ELISA are probably better choices (3).

Radiology

Chest x-ray may give diagnostic images in a few typical situations whereas plain abdominal film has very low specificity. Ultrasound due to its wide availability, moderate cost and high diagnostic rate (90%) is first of the diagnostic tools. It is equally important for follow-up. Gharbi's classification into types I to V perfectly describes the different presentations as well as the likely evolution of the lesions with time. CT-scan of abdomen and chest, while not usually essential for diagnosis, gives a better definition of cysts content, number, size and calcification together with relation to vessels or other organs. It is therefore fundamental in planing for surgery. It is similarly important in assessing complications or for follow-up. MRI, beside failing to demonstrate calcifications, is of questionable use as its superiority over CT-scan has yet to be established. Immunoscintigraphy is under evaluation (4).

Treatment

Surgical management

Technique and indications

Surgery is the first curative option. It has to be considered whenever possible. General contraindications to surgery apply. Surgery may also be more difficult in patients with multiple cysts and its value more doubtful in patients with calcified, dead or very small cysts (5).

  • In a radical approach, en bloc resection of the cyst is achieved by partial hepatectomy or more commonly by pericystectomy which is basically a non-anatomical liver resection performed at some distance from the cyst wall.
  • Cystectomy is the non-radical alternative. It consists in cyst de-roofing and cyst content evacuation without removal of the pericyst, plus or minus omentoplasty. No drainage is required except perhaps for infected or communicating cysts. Prior to this the cyst may be aspirated and protoscolicidal agent injected. The use of these agents to reduce peroperative spillage of viable protoscoleces is limited by the relatively common presence of cysto-biliary communications and subsequent possible chemical cholangitis, leading to devastating sclerosing cholangitis usually within a year. None of the popular agents is totally safe, they include 70–90% ethanol, 15–20% hypertonic saline, 0.5% cetrimide solution or 0.5% silver nitrate and hydrogen peroxide. They have to be left in place for 10–15 minutes to be effective.
  • Palliative surgery without cyst removal, by simple drainage of infected of communicating cysts is seldom performed. Transplantation may be considered as a life-saving measure for patients with AE and severe liver dysfunction, but it is associated with a relatively high risk of recurrence.

Results

Recurrence rate appears to be lower in radical procedures (2% at 3 years follow-up) as the outmost layer of the cyst and its surroundings are removed, decreasing the chances to leave behind any unidentified exogenous daughter cyst (present in up to 20%). This is however done at the cost of higher morbidity and mortality incidences (up to 24 and 2%). Nevertheless, non-radical treatment, due to its low morbidity and mortality rates (13 and 1% respectively) is popular. Meticulous surgical technique, the use of per-operative ultrasound for identification of other or daughter cysts together with a 4-weeks' pre-operative chemotherapy course are probably the key to modest contemporary recurrence rates following non-radical approach (8% after 3 years of follow-up).

Percutaneous approach

Whilst advocated by some, percutaneous aspiration of a cyst for diagnostic purpose is difficult to justify as diagnosis using the various techniques previously described is almost always achievable and this without dissemination risk.

However, percutaneous puncture (P) of a cyst under ultrasound guidance, aspiration (A) of its content, injection (I) of a protoscolicidal agent and re-aspiration (R) of it afterwards, the so-called PAIR technique, has gained interest for treating some hydatid lesions, especially small size (< 5–6 cm) type I, II and III ones (Gharbi's classification) (6, 7). Similar technique with drainage has been developed for larger lesions. Anaphylactic reactions have been less frequent than expected (4%) but mild allergic manifestations are more common (up to 12%). The risk for an equally serious problem, sclerosing cholangitis, would be lowered by a clear definition of cyst - biliary tree relationship (involving routine endoscopic retrograde cholangiopancreatography for some, ultrasound or cystograms for others) in order to exclude patients with communication. Antibiotic coverage is the use but infection of the cavity left behind can still happen. Biliary fistulas (up 6%) can lead to long term hospitalization. Overall morbidity is ranging from 20 to 32%. Benzimidazole therapy is believed to be mandatory but the protocol is not clearly defined. Short term results show 70% to 88% of responders by serologic and ultrasound standards. Even though the short term safety seems demonstrated, the option is still very controversial as the current series lack adequate follow-up to assess genuine recurrence rate and spillage issue. The outlined indications therefore should remain restricted to patients unsuitable for surgery.

Chemotherapy

Results yielded by the different drug therapies are inconstant. They are not without side effects and do not achieve cure in more than 30 to 40% of clinical situations. Primary medical treatment should therefore be restricted to contraindications to or recurrence after surgery (and PAIR?) and be maintained for 3 months or arguably longer. Albendazole 10 mg/kg/day, more effective than mebendazole, is the first choice (8). Chemotherapy used in preparation to surgery or PAIR is presumably desirable to reduce recurrence and spillage: in that regard, combination of albendazole and praziquantel seems to be more effective than albendazole alone.

Chemotherapy is of primary importance in AE where surgery is rarely an option due to extensive or disseminated disease.

Monitoring

Therapeutic monitoring and regular follow-up are essential due to the high recurrence rate after treatment. Several studies have shown a correlation between decrease in specific antibodies concentrations and favorable outcome after therapy. However, the variations are far from being constant or easy to interpret and do not necessarily reflect parasitic viability. Combination of immunological and radiological techniques is consequently required for accurate monitoring.

Prevention

The key issue in hydatidosis is prevention. Anthelmintic treatment of farm dogs remains currently the best way to reduce the prevalence of the disease. Vaccination of intermediate hosts is making substantial progress and will probably become integral part of eradication programs. This depends on governmental and health organizations policy.

References

1.
Parija S C. A review of some simple immunoassays in the serodiagnosis of cystic hydatid disease. Acta Trop. (1998);70:17–24. [PubMed: 9707361]
2.
Mistrello G, Gentili M, Falagiani P, Roncarolo D, Riva G, Tinelli M. Dot immunobinding assay as a new diagnostic test for human hydatid disease. Immunol Lett. (1995);47:79–85. [PubMed: 8537105]
3.
Bresson-Hadni S, Laplante J J, Lenys D, Rohmer P, Gottstein B, Jacquier P. et al. Seroepidemiologic screening of Echinococcus multilocularis infection in a European area endemic for alveolar echinococcosis. Am J Trop Med Hyg. (1994);51:837–846. [PubMed: 7810820]
4.
von Sinner W N. Imaging of cystic echinococcosis. Acta Trop. (1997);67:67–89. [PubMed: 9236940]
5.
Guidelines for treatment of cystic and alveolar echinococcosis in humans. Bull World Health Organ. (1996);74:231–242. [PMC free article: PMC2486920] [PubMed: 8789923]
6.
Filice C, Brunetti E. Use of PAIR in human cystic echinococcosis. Acta Trop. (1997);64:95–107. [PubMed: 9095291]
7.
Men S, Hekimoglu B, Yucesoy C, Arda I S, Baran I. Percutaneous treatment of hepatic hydatid cysts: an alternative to surgery. AJR Am J Roentgenol. (1999);172:83–89. [PubMed: 9888745]
8.
Horton R J. Albendazole in treatment of human cystic echinococcosis: 12 years of experience. Acta Trop. (1997);64:79–93. [PubMed: 9095290]
Copyright © 2001, W. Zuckschwerdt Verlag GmbH.
Bookshelf ID: NBK7009

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