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.
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 (pseudocyst / 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• Theoretically, echinococcosis can involve any organ.• Organs affected by E granulosus are the liver (63%), lungs (25%), muscles (5%), bones (3%), kidneys (2%), brain (1%), and spleen (1%).• The clinical presentation of a hydatid cyst is largely asymptomatic until complications occur.• The most common presenting symptoms are abdominal pain, dyspepsia, and vomiting.• The most frequent sign is hepatomegaly/palpable mass.• Jaundice and fever are each present in about 8% of patients.• Bacterial superinfection of a hydatid cyst can occur and present like a pyogenic abscess.• Rupture of the cyst into the biliary tree.• Free ruptures can result in disseminated echinococcosis and a potentially fatal anaphylactic reaction.
INVESTIGATIONS• Laboratory Studies• Routine laboratory blood workup: The results of routine laboratory blood work are nonspecific.• Liver involvement may be reflected in an elevated bilirubin or alkaline phosphatase level. Leukocytosis may suggest infection of the cyst. Eosinophilia is present in 25% of all persons who are infected, while hypogammaglobinemia is present in 30%.• Serodiagnostic techniques• Indirect hemagglutination test and the enzyme-linked immunosorbent assay (ELISA) have a sensitivity of 80% overall (90% in hepatic echinococcosis, 40% in pulmonary echinococcosis) and are the initial screening tests of choice.• Immunodiffusion and immunoelectrophoresis demonstrate antibodies to antigen 5 and provide specific confirmation of reactivity.• The ELISA test is useful in follow-up to detect recurrence.
IMAGING TECHNIQUES• Plain X-RAY Films:• Findings from plain films of the chest, abdomen, or any other involved site are nonspecific and mostly non revealing. A thin rim of calcification delineating a cyst is suggestive of an echinococcal cyst.
• Ultrasound:• 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.
Hydatid cyst of the liver on ultrasound examination. Note the multiloculated appearanceof the cyst due to the presence of multiple daughter cysts. Detached germinalmembranes and brood capsules can be seen in the more anterior daughter cyst. Thismultiseptated anechoic or hypoechoic appearance on sonography is typical of a hydatidcyst.
Gharbi’s Classification• Type I : pure cystic fluid Collection (spherical- oval, thick-walled)• Type II : fluid Collection with membrane separation• Type III : Fluid collection with septa• TypeIV: heterogeneous (hypoechoic- hyperechoic- intermediate) pattern• Type V: completely calcified (Reflecting) walls
Computed Tomographic scan• Has the highest sensitivity of imaging of the cyst (98%). 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.It is supported by floating membrane within the cysts on CT scan.
Fig. 3.34 Type I, II and IIIunruptured hydatid cysts in 4different patients. (A)Univesicular uncomplicated typeI cyst in a 54-year-old man. (B)Multivesicular type II hydatid withmultiple daughter cysts giving aseptated appearance to the cystin a 21-year-old woman. (C) Oldhypermature liver hydatid in a64-year-old man. Non-contrastCT shows calcification in thecyst wall and matrix and fluidwithin the cyst, suggesting it isstill evolving and not innocuousand should be treated. (D) Twohydatid liver cysts in a 75-year-old man. The largerpseudotumoral cyst has somecalcification in its wall while thesmaller type III cyst is totallycalcified on non-contrast CT. CT SCAN
Other Imaging Techniques• 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) Images show the cysts adequately, but MRI offers no real advantage over CT scan.
TREATMENT• The treatment of choice is surgery.• Available Options: • Medical • Per-cutaneous • Endoscopic • Surgical
MEDICAL TREATMENT• CHEMOTHERAPY FOR HYDATID DISEASE OF LIVER• The compounds in common clinical use are mebendazole and albendazole which inhibit the uptake of glucose by the parasite and inhibit production of adenosine triphosphate.• 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.
MEDICAL TREATMENT• Mebendazole:Its disadvantages are that it is poorly absorbed from the gastrointestinal tract. It is no longer used in hydatid disease.• Albendazole• . 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.• 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.
PERCUTANEOUS DRAINAGE OF HYDATID CYST (PAIR)• PAIR (Puncture, Aspiration, Injection, Re- aspiration), was proposed in 1986 by the Tunisian team that first used it in a prospective study.• PAIR is a relatively recent and minimally invasive therapeutic option, that complements or replaces surgery which was long considered as the only treatment for CE.• If a catheter is temporarily left in the cyst after the procedure for drainage (D), the acronym PAIRD should be preferred.
PAIR• 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• The cysts should be larger than 5 cm in diameter and type I or II according to the Gharbi ultrasound classification of liver cysts PAIR can be performed on type III cysts as long as it is not a honeycomb cyst.
INDICATIONS FOR PAIR• Patients with:• Non-echoic lesion ≥ 5 cm in diameter (TYPE 1)• Cysts with detachment of membranes (TYPE2) and/or with daughter cysts (TYPE 3),• Multiple cysts if accessible to puncture• Infected cysts• Also• Pregnant women• Children >3 years old• Patients who fail to respond to chemotherapy alone• Patients in whom surgery is contraindicated• Patient who refuse surgery• Patients who relapse after surgery
Contraindications for PAIR• Non-cooperative patients and inaccessible or risky location of the cyst in the liver.• Cyst in spine, brain and/or heart.• Inactive or calcified lesion.• Cysts communicating with the biliary tree.• Cysts open into the abdominal cavity, bronchi and urinary tract.
PAIR• Benefits Of PAIR:• Minimal invasiveness• Reduced risk compared with surgery• Confirmation of diagnosis• Removal of large numbers of protoscolices with the aspirated cyst fluid• Improved efficacy of chemotherapy given before and after puncture (probably because of an increased penetration of antihelminthic drugs into cysts re-filling with hydatid fluid )• Reduced hospitalization time• Cost of the puncture and chemotherapy usually less than that of surgery or chemotherapy alone• Risks Of PAIR:• Same risks as any puncture ( haemorrhage, mechanical lesions of other tissues, infections )• Anaphylactic shock or other allergic reactions• Secondary echinococcosis caused by spillage• Chemical ( sclerosing ) cholangitis if cysts communicate with the biliary tree• Sudden intracystic decompression, thus leading to biliary fistulas• Persistence of satellite daughter cysts• Systemic toxicity of alcohol or hypertonic saline in case of large cysts (total volume injected must be carefully calculated)
HOW TO PERFORM PAIR• Basic Requirements:• Trained personnel• Equipment, Supplies, Drugs (minimum requirements) :• Ultrasound equipment (portable apparatus) with a 3.5 - 5 MHz probe• Needles (lumbar puncture needles, “fine needles”, especially for multiple daughter cysts)• Catheters for large cysts (> 5 cm)• 95 % alcohol or hypertonic (at least 15 %) saline as protoscolicide agent• “Fast test” for checking the presence of bilirubin in the cystic fluid• Optic microscope• Drugs to be used in case of allergic reactions-anaphylaxis (epinephrine, hydrocortisone); basic resuscitation equipment• Blood pressure measurement and intravenous catheter must be left in the forearm during the procedure, so that resuscitation can take place immediately, should the need arise
PAIR STEP BY STEP• PAIR Protocol (Minimum Requirements):1. Prophylaxis with albendazole2. Puncture and parasitological examination (if possible) or fast test for antigen detection in cyst fluid3. Aspiration of cystic fluid (10-15 cc)4. Test for bilirubin in cyst fluid5. If bilirubin present: →→ →→ stop procedure6. If no bilirubin present: →→ →→ aspirate all cystic fluid7. Injection of 95 % ethanol solution or hypertonic saline (1/3 of the amount of aspirated fluid)8. Re aspiration of protoscolicide solution after 15 minutes9. New parasitological control if possible
Management of the patient in case of allergic/anaphylactic reaction• • Skin reaction (urticaria [hives], oedema) without arterial blood pressure (ABP) changes (ABP>115-70 mm HG):• Inject hydrocortisone and/or anti-histamine drug• Careful monitoring of ABP• • Moderate decrease in ABP (115-70>ABP>95-50 mm Hg)• Temporarily stop the procedure• Careful monitoring of ABP• • Marked decrease in ABP (ABP<9O-50 mm Hg)• Stop the procedure• Inject 1/3 mL of epinephrine (1mg/mL) IM or (3mL of a saline solution of epinephrine-1mL/10mL-through the IV catheter)• Careful monitoring of ABP• • If ABP<95-50:• new injection of epinephrine up to 1mL (IM) or 10mL of the saline solution of epinephrine (IV)
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.
SURGICAL TREATMENTIndications: Large liver cysts with multiple daughter cysts;superficially located single liver cysts that may rupture(traumatically or spontaneously); liver cysts with biliary treecommunication or pressure effects on vital organs orstructures; infected cysts.Contraindications: General contraindications to surgicalprocedures (eg, extremes of age, pregnancy, severepreexisting medical conditions); multiple cysts in multipleorgans; cysts that are difficult to access; dead cysts;calcified cysts; and very small cysts are contraindications.
PRINCIPLES OF HYDATID SURGERY• 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 operation• All the surgical procedures can be divided into two large groups, conservative group and radical group
CONSERVATIVE TECHNIQUE(open cystectomy)• 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 and suture closure of the pericyst cavity after filling it with saline.
RADICAL SURGICAL PROCEDURES• Pericystectomy• Lobectomy• 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.
• 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 walls.
COMPLICATIONS OF SURGERY• Biliary leakage is the most frequent postoperative complication following surgery for hydatid cyst 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 third.
FOLLOW UP• Chemotherapy: Postoperative treatment with benzimidazoles is continued for 1 month in patients with CE who have undergone complete resection or PAIR successfully. The treatment is continued for 3-6 months for patients with resected AE, incompletely resected CE, spillage during surgery or PAIR, and metastatic lesions.• Laboratory tests: Patients on benzimidazoles should have a CBC count and liver enzyme evaluation performed at biweekly intervals for 3 months and then every 4 weeks to monitor for toxicity. ELISA or indirect hemagglutination tests are usually performed at 3-, 6-, 12-, and 24-month intervals as screening for recurrence of resected disease or aggravation of existing disease.• Imaging: Ultrasonography and/or CT scan are used in follow- up at the same intervals as the laboratory tests or as clinically indicated.