HYDATID CYST OF

LIVER

Dr.Anil Haripriya 

Introduction 

Hippocrates recognized human hydatid over 2,000 years ago. The

Arab physician, Al Rhazes, made reference to hydatid disease of the

liver in AD 900.  

Liver hydatid disease is a zoonosis caused by caused by larva of the

dog tapeworm, Echinococcus granulosus, with man acting as an

accidental intermediate host. 

Liver hydatidosis is characterized by progressive growth of the

hydatid cyst, which in its mature form is a fluid filled cavity, delimited

by an external dense host fibrous reaction (pericyst) and two internal

parasite derived layers (endocyst). The hydatid cyst grows slowly

and remains asysmptomatic for many years. Symptoms arise only

when the cyst has grown large enough to cause the pressure on

adjacent organs or when a complications occurs. Infection and

intrabiliary rupture are the most common complications. 

Etiopathogenesis  

Causative Agent Intermediate host Final host 

Echinococcus granulosus Sheep, Human dog

(hydatinosus, cysticus)

Echinococcus vogeli Paca dog, fox

(Brazil)

Echinococcus multilocurlaris Rodents dog,fox, (alveolaris)

Echinococcus oligarthrus ? Human dog, fox 

In E. multilocularis infestation the germinal layer of the cyst sends out processes Into the surrounding host tissue which in turn form fluid filled pockets containg proto-Scolices.The germinal layer continues to spread and multiply like a cancer,therefore It carries mortality upto 50%. 

E.vogeli infestation is very rare and found occasionally in Brazil.Paca

a wild Rodent is the intermediate host and final host is the hunting or

domestic dog. 

Epidemiology 

It is world wide in distribution and is endemic in many countries like

Mediterranean area, the Middle East and South America. In India it is

found in the northern states.  

Life Cycle 

The adult form of Echinococcus granulosus resides in the small

intestine of dogs. The ova from the adult worm are shed through the

canine feces into the environment, where the intermediate host

sheep and humans ingest the eggs, in humans after entering

proximal portion of the small intestine, the larvae burrow through the

mucosa, enter the portal circulation and travel to liver. The cycle is

completed when dogs eat the carcass of animals infected with the

hydatid cysts. 

Pathology 

A primary cyst in the liver is composed of three layers: 

1.       Adventitia (psuedocyst / pericyst) – consisting of

compressed liver parenchyma and fibrous tissue induced by the

expanding parasitic cyst. 

2.       Laminated membrane (ectocyst) – is elastic white covering,

easily separable from the adventitia. 

3.      Germinal epithelium (endocyst) – is a single layer of cells

lining the inner aspects of the cyst and is the only living component,

being responsible for the formation of the other layers as well as the

hydatid fluid and brood capsules within the cyst. In some primary

cysts laminated membranes may eventually disintegrate and the

brood capsules are freed and grow into daughter cysts. Sometimes

the germinal Epithelium protrudes out towards the external side of

the cyst, to form exogenous daughter cysts, which if left untreated

may cause recurrence. 

The Hydatid cysts are slow growing approx 2 – 3 cm / year and

remain inapparent for long time. 

CLINICAL FEATURES 

Patients with simple or uncomplicated multivesicular or univesicular

cysts are asymptomatic. When symptoms occurs they are caused by

pressure on the adjacent organs. Abdominal pain and tenderness

are the most common complaints followed by palpable mass.

Jaundice and ascites are uncommon. With secondary infection

tender hepatomegaly, chills, and spiking temperatures occurs.

Urticaria and erythema occur in cases of generalized anaphylactic

reaction. With biliary rupture the classic triad of jaundice, biliary colic

and urticaria occurs.  

COMPLICATIONS OF HYDATID CYST 

Intrabiliary rupture of Hydatid cyst

When ruptured in to biliary tree, hydatid cysts commonly manifest

with findings of biliary obstruction and cholangitis. The presence of

dilated common bile duct, jaundice, or both in addition to a cystic

lesion of liver is strongly suggestive of a hydatid cyst with intrabiliary

rupture. This complication can be most specifically diagnosed by

ERCP or PTC. ( because of risk of intraperitoneal rupture of the

hydatid cyst which may result in peritoneal dissemination and

anaphylactic reactions because of the spillage of the highly antigenic

cyst fluid PTC is contraindicated in hydatid disease of liver). The

presence of intrabiliary rupture requires exploration and drainage of

the biliary tract. During the exploration the biliary tree is cleared of

any hydatid material which is confirmed by intra-operative

choliangiography or choledochoscopy. After evacuation of hydatid

elements from the biliary tree, either side to side

choledochoduodenostomy or external T-tube drainage is done.  

Infection

Suppuration of cysts takes place in 5 to 15 % of cases. The clinical

picture resembles liver abscess and urgent surgery is necessary.  

Recurrence

Incidence of recurrence is estimated to range from 8.5 % to 25 %.

The causes of recurrence are peritoneal spillage and implantation

during operations. New cyst formation from exogenous vesicles

attached to the remaining pericyst after conservative treatment and

reinfection.  

Coexisting cholelithiasis

Cholelithiasis exists with liver hydatid in three forms: true hydatid

lithiasis, parahydatid lithiasis and accidential coincidence. In true

hydatid lithiasis, histologic examination reveals the presence in

central part of the stones of hydatid elements that constitute the

lithogenic nidus. The parahydatic lithiasis is attributed to the

abnormal delay in passage of bile into gallbladder provoked by an

adjacent hydatid cyst. 

INVESTIGATIONS 

Routine laboratory tests are rarely abnormal occasionally

eosinophilia may be present. Serum alkaline phosphatase levels are

raised in one third of patients.  

Immunological tests

Serological tests detect specific antibodies to the parasite and are

the most commonly employed tools to diagnose past and recent

infection with E. granulosus. Detection of IgG antibodies implies

exposure to the parasite, while in active infection high titres of

specific IgM and IgA antibodies are observed. Detection of

circulating hydatid antigen in the serum is of use in monitoring after

surgery and pharmcotherapy and in prognosis. ELISA is used most

commonly, but alternate techniques are counter-immuno-

electrophoresis and bacterial co-agglutination. Elisa techniques have

a high sensitivity above 90% and are useful in mass scale screening.

The counter-immuno-electrophoresis has highest specificity

(100%)and high sensitivity (80 – 90%).  

CASONI TEST

It has been used most frequently in the past but this cutaneous

hypersensitivity reaction using hydatid fluid is at present considered

only of historical importance. The allergen is rarely standardized and

infestation with other helminthes particularly cestodes can give a

false positive response. 

Imaging techniques 

Plain abdominal radiography may reveal calcification,

hepatomegaly, or indirect evidence of an hepatic SOL. (for eg.

Elevated hemi diaphragm, right lung basal collapse, and pleural

effusion). A coincidental lung cyst may be picked up on a plain

skiagram.  

Ultrasound – is currently the primary diagnostic technique and has

diagnostic accuracy of 90%. Findings usually seen are: 

a)       Solitary Cyst – anechoic univesicular cyst with well defined

borders and enhancement of back wall echoes in a manner similar to

simple or congenital cysts. Features are suggesting a hydatid

etiology include dependent debris (hydatid sand) moving freely with

change in position; presence of wall calcification or localized

thickening in the wall corresponding to early daughter cysts.

b)       Separation of membranes (ultrasonic water lily sign) due to

collapse of germinal layer seen as an undulating linear collection of

echoes.

c)       Daughter cysts - probably the most characteristic sign with

cysts within a cyst, producing a cartwheel or honeycomb cyst.

d)       Multiple cysts with normal intervening parenchyma

(differential diagnosis are necrotic secondaries, Polycystic liver

disease, abscess, chronic hematoma and biliary cysts.

e)       Complications may be evident such as echogenic cyst in

infection or signs of biliary obstruction usually implying a biliary

communication.  

Gharbi Classification on ultrasonographic features of Hydatid Cyst3 

Type Ultrasound Appearance

I Pure fluid Collection

II Fluid collection with a split wall

III Fluid collection with septa

IV Heterogeneous echo pattern

V Reflecting walls 

Type V cysts determined by ultrasound to be calcified and have been

assumed to be dead cysts and do not require surgery. 

Computed Tomographic scan - has the highest sensitivity of

imaging of the cyst (100%). It is the best mode to detect the number,

size, and location, of the cysts. It may provide clue to presence of

complications such as infection, and intrabiliary rupture. CT features

include sharply marginated single or multiple rounded cysts of fluid

density (3 – 30 Hounsfield units) with a thin dense rim.  

Angiography – of the liver is suggestive but due to lack of specificity

and availability of lesser invasive techniques it is rarely required. It

may be required in a differential diagnosis of suspected malignancy

or vascular malformation. Typical features include an avascular

lesion with vascular displacement and a thin peripheral halo of higher

density. 

Direct cholangiography – (Endoscopic or percutaneous) may be

required in suspected intrabiliary rupture and bile duct obstruction.

ERCP is also a valuable method for detecting post-operative

complications involving the biliary tree following surgical

intervention. 

Radionuclide scan – has largely replaced by ultrasound and CT

scan. It remains most accurate method of demonstration of a

bronchobiliary fistula.  

Immunoscintigraphy – is an innovation using radiolabelled

antibodies to antigens in the parasite.  

Magnetic resonance Imaging (MRI scan) – MRI delineates the cyst

capsule better than CT scan, as a low intensity on both T1 and T2

weighted images. However CT scan is better in demonstration of

mural calcifications, cysts less than 3 cm may not show any specific

features and small peritoneal cysts may be missed. 

ASPIRATION CYTOLOGY

Hydatid was considered to be a contraindication for FNAC. However,

it may be used in diagnosis of hydatidosis if radiological studies

reveal a cyst and serological tests are equivocal. Diagnostic features

include presence of laminated membrane, which gives a positive

periodic acid schiff reaction, and a diagnosis of hydatid may be

presumed.  

TREATMENT 

The treatment of choice is surgery. The principle of hydatid surgery

are 1) Total removal of all infective components of the cysts; 2) the

avoidance of spillage of cyst contents at time of surgery; 3)

management of communication between cyst and adjacent

structures; 4) management of the residual cavity; 5) minimize risks of

operation7,8. 

All the surgical procedures can be divided into two large groups,

conservative group and radical group. The conservative

technique consists of aspiration of the cyst, instillation of scolicidal

agents and evacuation of the cyst contents and leaving the pericyst.

The residual pericyst is managed by marsupialization, which consists

of suturing the edges of opened pericyst with the skin, capitonnage

(suture obliteration), partial pericystectomy, omentoplasty (omentum

is thought of fill residual cavity, to assist healing of raw surfaces and

to promoted resorption of serosal fluid and macrophagic migration of

septic focus)10, and suture closure of the pericyst cavity after filling it

with saline. 

Intracystic injections of scolicidal agents used in the past are

formaldehyde solution, cetrimide solution 0.5%, hypertonic saline

solution, 0.5% silver nitrate solution, and hydrogen peroxide solution.

The arguments against the use of conventional intracystic solutions

are: 

1.       In a large univesicular cyst, dilution of the scolicidal solution is

unpredictable and impairs its efficacy. 

2.       If cyst communicates with the biliary system, it can lead to

serious complications like sclerosing cholangitis and acute

pancreatitis, have been reported with use of formaldehyde and

hypertonic saline. Air embolism has been reported with the use of

hydrogen peroxide.  

3.       Cetrimide solution produces severe adhesions formation. 

The best choice is silver nitrate solution 0.5% which has been

reported to be safe and efficacious.  

The conservative surgical procedures are easy to perform but the

postoperative complications and duration of hospital stay are not

satisfactory. 

Radical surgical procedures include cystectomy, pericystectomy,

lobectomy and hepatectomy Radical procedures have lower rate of

complications and recurrences but many authors consider them

inappropriate, claiming that intraoperative risks are too high for a

benign disease.  

Cystectomy – The procedure of choice is cystectomy. The

procedure involves removal of hydatid cyst, comprising laminar layer,

germinal layer and cyst contents i.e. daughter cysts and brood

capsules. No attempt is made to remove the pericyst. The procedure

is simple to perform and has low recurrence rates.  

Pericystectomy – this procedure involves non-anatomical resection

of cyst and surrounding compressed liver tissue. This is technically

more difficult procedure than cystectomy and can be associated with

considerable blood loss; it can also be hazardous in the case of large

and complicated cysts when the cyst distorts vital anatomical

structures.  

Hepatic resections – is the only surgical therapy for E. multilocularis

as the disease is infiltrative and disease margin is ill defined. The

arguments against hepatic resection as a primary modality of

treatment are that outside of dedicated liver units there is

considerable morbidity and mortality from resection of what is

essentially a benign condition and also distortion of anatomy makes

surgery more difficult.

LAPAROSCOPIC MANAGEMENT OF HYDATID CYSTS

A special instrument has been developed for the removal of the

hydatid cyst with the laparoscope called the perforator-grinder-

aspirator apparatus. The instrument penetrates the cyst, grinds the

particulate matter and sucks it all out. The advantage of this

instrument over that of conventional suction apparatus is that it does

not gets blocked by the daughter cysts and laminated membranes.

Vacuum obliteration of cavity is carried out with application of – 250

mbar of negative pressure, which obliterates the cystic cavity by

clinging to the opposing cyst walls9.

COMPLICATIONS OF SURGERY

Biliary leakage is the most frequent postoperative complication

following surgery for hydatid of liver. It has been reported to occur in

about 50% of cases because of the small-undetected communication

between the cyst and the bile ducts.  

The surgical management of hydatid disease of liver carries a

mortality rate of 0.9 to 3.6 % and recurrence up to 11.3 % within 5

years. Operations carry a progressively higher mortality – increasing

from 6 % after second to 20% after third1. 

PERCUTANEOUS DRAINAGE OF HYDATID CYST 

Puncture of hydatid cysts have been discouraged in the past due to

the potential risk of Anaphylactic shock and peritoneal dissemination.

However, in the recent years percutaneous drainage has been used

successfully to treat the hepatic hydatid cysts. Khuroo et al from

India reported 88% disappearance of cysts with percutaneous

drainage which was preceded by Albendazole therapy (10 mg/kg

body weight) for 8 weeks5,6. 

ENDOSCOPIC MANAGEMENT OF HYDATID CYST 

The ERCP is effective in diagnosing biliary tree involvement from the

cyst. The Endoscopic management is useful in presence of

intrabiliary rupture, which requires exploration and drainage of the

biliary tract and also after surgery in presence of residual hydatid

material (membranes and daughter cyst) left in biliary tree. During

the endoscopic exploration the biliary tree is cleared of any hydatid

material with a balloon catheter or a dormia basket. The endoscopic

sphinterotomy is also performed to facilitate drainage of the common

bile duct.  

CHEMOTHERAPY FOR HYDATID DISEASE OF LIVER 

The compounds in clinical use are the benzimidazole derivatives

(mebendazole and albendazole), which inhibit the uptake of glucose

by the parasite and inhibit production of adenosine triphosphate,

isoquinolone compounds (praziquantel) and immunostimulatory

compounds: isoprinosine and trans-2- phenoxycyclohexonol ethers 

Mebendazole

was the first drug to show any activity against hydatid cysts. It

inhibits glucose uptake in susceptible parasites resulting in depletion

of the worms energy sources and slow death. Its disadvantages are

that it is poorly absorbed from the gastrointestinal tract. Although

progressively higher doses for long periods have been given in an

attempt to boost plasma concentrations, it has resulted in a plethora

of side effects like prolonged fever, major liver disturbance, bone

marrow depression and glomerulonephritis. It is no longer used in

hydatid disease. 

Albendazole

The principal metabolite, albendazole sulfoxide has antihelminthic

activity over a half-life of 8.5 hours. A dose of 10 mg/kg/day achieves

an intra cyst concentration in excess of 100 ng/ml, which is within the

effective scolicidal range. Albendazole is administered in a dose of

10 – 15 mg/kg/day in adults or a fixed dose of 400 mg twice daily.

The treatment is given in cycles of 28 days with two weeks treatment

free periods between the cycles. The different schedules for the

treatment are: 

1.       Inoperable cases - as primary treatment - 3 cycles

2.       Pre-operatively – to reduce the risk of recurrence 6 weeks

continuous treatment

3.       Post-operatively to prevent recurrence in cases of

intraoperative cyst spillage – 3 cycles. 

Cure is defined as disappearance of the cyst, improvement is

defined as > 25% reduction is size of cyst, membrane separation

and appearance of calcification and deterioration as an increase in

cyst size. As reported in study by Horton et al2 on 253 patients, cure

rate was 32%, improvement was seen in 43%, 21% had no response

and 1.5% patients showed increase in size of cyst. 

Side effects of Albendazole therapy are: mild abdominal pain,

nausea, vomiting, pruritis, dizziness, alopecia, rash and headache.

Occasionally leucopoenia, eosinophillia, icterus, and mild elevation in

transaminase levels is seen.  

Praziquantel

increases the permeability of plasma membrane to calcium ions

resulting in rapid loss and extreme contraction and paralysis of

worms. Oral dose of 50 mg/kg/day for upto two weeks shows rapid

scolicidal activity. Side effects are mild headache, dizziness,

drowsiness, abdominal pain, and nausea. WHO has recommended

the use of praziquantel preoperatively to achieve the sterilization of

the cysts or postoperatively in cases of cyst rupture and spillage.  

Immunostimulatory compound

Isoprinosine is an immunomodulatory drug, which appears to act via

cytolytic effects on the cellular elements of the germinal layer, While

the persisting superficial structures prevent the dissemination of

viable cells. The drug has shown efficacy against E. granulosus and

E. multilocularis in an animal model.  

References 

1.        Kumar A, Lal BK, Chattopadhay TK. Hydatid disease of liver – Non-surgical

options: J Assoc Physicians India 1993; Vol. 41.

2.        Morris DL, Taylor DH, Optimal timing of postoperative albendazole therapy

prophylaxis. Ann Trop Med 1988; 82: 65–66.

3.        Gharbi HA, Hassine W, Brauner MW: Ultrasound examination of hydatid cyst

liver, Radiology 1981; 139:459-463.

4.        Menegelli UG, Martinelli LC, Angeles M. Polycystic hydatid disease

(Echinococcus vogeli) clinical, laboratory and morphological findings in nine Brazilian

patients. J Hepatology, 1992; 14:203-210.

5.        Khuroo MS, Waini NA, Javid G, Khan BA. Percuatneous drainage compared with

surgery for Hepatic Hydatid Cysts. N Eng J Med 1997; 13:337–400.

6.        Palez V, Kugler C, Correa D, Carpio MD. PAIR as percutaneous treatment of

hydatid liver cysts. Acta Tropica 2000; 75:197–202.

7.        Agoglu M, DavidsonBR. A rational approach to the terminology of hydatid

disease of liver. J .Infection 1992; 24:1–6.

8.        Magistrelli P, Masetti r, Coppola R, Messia A. Surgical treatment of hydatid

disease of liver: a 20 year experience. Arch Surg 1991; 126:518–523.

9.        Saglam A. Laparoscopic treatment of liver hydatid cysts. Surg Lap Endosc

1996; 6:16–21.

10.     Dizri C, Paquet JC, Hay JM. Omentoplasty in the prevention of Deep abdominal

complications after surgery for hydatid disease of liver: a multicenter, prospective

randomized trial. J Am Coll Surg 1999; 188:281– 289.