- Due to infection with the helminth Ecchinococcus granulosa
- Adult worm is found normally in the dog and sheep intestine
- Man is an accidental intermediate host
- Infection seen in Mediterranean areas, Australia and South America
- Liver is the commonest organ involved
- Cysts are unilocular, can be up to 20 cm in diameter and may be multiple
- Daughter cysts may develop
- 70% develop in the right lobe of the liver
- Lung, brain and bone can also be infected
- Pathologically hydatid liver cyst has three distinct layers:
- Ectocyst - fibrous advential layer due to host response
- Middle layer - laminated membrane of proteinaceous material
- Endocyst - inner germinal layer from which the scolices may be detached
Clinical features
- Clinical presentation is often non-specific and may be asymptomatic
- 60% have right hypochondrial pain
- Only 15% become jaundiced
- Other features include skin rashes, pruritus and allergic reactions
- Cysts can rupture resulting in bronchobiliary fistula
Investigation
- 30% of patients have an eosinophilia
- Diagnosis can be confirmed by indirect haemagglutinin assay
- Plain abdominal x-ray may show calcification in cyst wall
- Cyst can be imaged with ultrasound or CT
- Aspiration should not be performed if hydatid disease is suspected
- Associated with risk of dissemination of infection or anaphylaxis
Management
- Pharmacological treatment is not curative
- Used as an adjunct to surgery to kill spilled scolices
- The drugs of choice are albendazole, mebendazole and praziquantel
- If surgery is required a laparotomy is performed to exclude other cysts
- The liver is packed off with hypertonic saline-soaked swabs
- Cysts are then decompressed with trocar and cannula
- Scolicidal agent (e.g. hypertonic saline or 0.5% silver nitrate) can be injected into cyst cavity
- Cavity is filled with saline and a suction drain inserted
- Alternatively liver cysts can be excised
Picture supplied by Dr T
Bombardieri, Italy
- Hepatic resection may be required for recurrent cysts
- Recurrence rate is approximately 5% at 5 years
Complications
- Operative mortality is less than 2%
- Complications include:
- Subphrenic abscess
- Prolonged cyst drainage
Bibliography
Ayles H N, Corbett E L, Taylor I et al. A combined medical and surgical approach to
hydatid disease: 12 years experience at the Hospital for Tropical Diseases, London. Ann R
Coll Surg Eng 2002; 84: 100-105.
Sayek I, Onat D. Diagnosis and treatment of uncomplicated hydatid cyst of the liver. World
J Surg 2001; 25: 21-27. |