Cystic Echinococcosis of the Liver: Experience From a Danish Tertiary Reference Center (2002–2010)


Sonia Branci, MD, Department of Radiology, Rigshospitalet, Blegdamsvej 9, Copenhagen OE 2100, Denmark. E-mail:


Background. Cystic echinococcosis (CE) of the liver can be treated with ultrasound-guided puncture, aspiration, injection, and re-aspiration (PAIR), with surgery and with benzimidazole derivatives. The aim of this study was to review available data concerning treatment modality and outcome for patients treated for CE of the liver in a Danish tertiary reference center.

Methods. A search was made for patients treated for CE infection between January 1, 2002 and January 1, 2010. All relevant patient records and radiology exams were scrutinized and all cysts were re-classified according to the WHO-IWGE, blinded as to which treatment the patient had received. PAIR was performed as a first choice treatment and surgery was reserved for cases where PAIR was impossible. Inactive cyst stages received medical treatment only.

Results. The search revealed 26 cases with confirmed CE of the liver. Nine patients underwent PAIR and nine patients surgery as a first choice treatment. Three patients were treated with PAIR secondary to surgery and one patient was treated with surgery secondary to PAIR. For all PAIR treatments, the success rate was 58% regardless of cyst stage and for surgery the success rate was 70%. The difference between the rates was not statistically significant (p = 0.67).

Conclusion. CE is a rare disease in Denmark and our study is the first describing clinical management of CE in our institution.

Cystic echinococcosis (CE) is endemic in parts of Africa and Europe, the Middle East, large parts of Asia, Latin America, and Australia. In Scandinavia, almost all cases are imported.

CE is caused by an infection with the cestode Echinococcus granulosus. It mainly involves the liver (70% of cases) and the lungs (10% of cases), but can also be found in several other organs.1,2 CE may cause major morbidity and can be fatal. However, many cases are silent and undiagnosed for years and even decades. Symptoms at presentation depend on cyst location and size.

Treatment of hepatic CE can be surgical, medical with benzimidazoles, and/or by means of percutaneous ultrasound-guided puncture, aspiration, injection, and re-aspiration (PAIR).

Wherever possible, surgery or, with increasing frequency, PAIR is performed to obtain cure.3 This practice was implemented in the 1990s in Copenhagen, Denmark, the method of choice being aspiration of cyst contents and injection of hypertonic saline as a scolicidal agent in one session according to the WHO guidelines,2 in combination with albendazole.

The aim of the study was to review available data on treatment modality and results for patients treated for CE of the liver in the period between January 2002 and January 2010 at Rigshospitalet, a tertiary reference center in Copenhagen, Denmark.

Materials and Methods


A retrospective search was performed for patients treated for CE at the Department of Infectious Diseases and the Department of Gastrointestinal Surgery, Rigshospitalet, Denmark between January 2002 and January 2010. All records of possible CE regardless of anatomical location were retrieved and scrutinized. We registered age, sex, country of origin, known expositions, serology of E. granulosus, and imaging [computed tomography (CT) and ultrasonography (US)], number of cysts including their location, PAIR, surgical events, admission time in relation to surgical or PAIR treatment, complications (recurrence of the cyst, pain, hemorrhage, infection), and duration of medical treatment with albendazole.

Patients for whom CE in the liver was not confirmed by imaging and/or serology were excluded from the study.

Our search yielded 44 patients, of whom only 26 had confirmed hepatic CE. For the remaining 18 patients, the diagnosis listed in the database was erroneous (cyst located elsewhere or diagnosis rejected after thorough investigation).


For all patients, concise written radiological reports (produced by the examining radiologist) were available. For 24 patients, corresponding images were also stored in the Picture Archiving and Communication System of our institution. The examining radiologist had not in all cases classified the cyst according to the WHO classification (Figure 1). We classified all the cysts retrospectively based on the written radiological report and on a review of the stored US images (when available) according to the WHO-IWGE, blinded to whether the patients had been treated with PAIR.

Figure 1.

WHO-IWGE standardized classification: CE1: unilocular, unechoic cyst; CE2: multiseptated, “honeycomb” cyst; CE3A: cyst with detached membranes; CE3B: cyst with daughter cysts in solid matrix; CE4: cyst with heterogenous content—no daughter cysts; CE5: solid cyst with calcifications. (Figure 1 is reproduced with kind permission from Brunetti et al., Rightslink Copyright Clearance Center; License Number: 2537000187694.)

Serology was performed by an immunohemagglutination test (Cellognost-Echinococcosis Kit, Siemens Healthcare Diagnostics Products GmbH, Marburg, Germany) used in accordance with the instructions of the manufacturer. The results were evaluated with a cut-off titer of 1:256, as recommended by the manufacturer. Titers between ≥1:16 and ≤1:128 were considered borderline positive.


All US evaluations were performed by radiologists. PAIR was conducted under US guidance when there were no contraindications (eg, communication with the bile ducts). The procedure was performed at the Department of Ultrasound, Rigshospitalet, without sedation of the patient and without assistance from anesthesiology staff in the examination room (although assistance was readily available should it be required). Informed consent was obtained from the patient. Intravenous access to a peripheral vein was established and adrenalin 1 mg/mL for intravenous administration was available in case of an anaphylactic reaction. The area of skin chosen for puncture was tagged and disinfected with a 70% ethanol solution. After injection of local anesthetic (10 mL of lidocaine 10 mg/mL), the cyst was punctured with a five to six French pig-tail catheter under US guidance. As much cyst material as possible was aspirated, inspected for bilirubin, and collected for subsequent microscopy for the presence of free “hooks” from scolices or scolices themselves. Hypertonic saline (20%) in an amount equalling half the amount of aspirated cystic fluid was injected into the cyst cavity, where it remained for 25 to 30 minutes before being re-aspirated. The catheter was removed and the liver reexamined by US for acute bleeding. The patient rested in bed for 4 h following the procedure. The cyst material was collected for histological and chemical analysis at the Department of Pathology, Rigshospitalet.

The criterion for cure after PAIR was permanent solidification of the cyst(s) (stage CE4/CE5).


Before 2002, CE was primarily treated with surgery in our center. From 2002 and onwards, PAIR was chosen as a primary treatment whenever possible. Surgical treatment was chosen if the cyst communicated with the biliary system or was inaccessible to PAIR due to lack of a viable access for anatomical reasons.

Surgical procedures were decompression of the cyst with instillation of 10% saline; removal of cyst contents followed by marsupialization and omentoplasty; or radical liver resection.4 For surgery, criteria for cure were disappearance or solidification of the original cyst cavity.

Descriptive statistics were calculated using Microsoft Excel 2000 (Redmond, WA, USA). Fisher's exact test was applied to compare proportions.



Most (22/26) patients had only one cyst, three had two cysts, and one had three cysts. Ten patients were male and 16 were female.

Median age at the first presentation of the disease was 36 years (interquartile range 29–45 y). Exposure to risk factors included living in close contact with sheep and dogs. The countries of origin of the patients are shown in Table 1.

Table 1.  Nationalities of patients included in the study
CountryNumber of patients
  1. *One was born and raised in Denmark but had Turkish family and was visiting family in Turkey on most holidays. Another had lived in Africa as a child and had traveled much in India and Pakistan. The last patient was positive for Echinococcus multilocularis and had mainly traveled in Europe but also reported shorter stays in North Africa and Istanbul.

Former Yugoslavia2
Total number of patients26

Symptoms, in all patients, were abdominal pain in the upper right or left quadrant. Four patients also had extrahepatic manifestations of CE, including pleural effusion (N = 2), lung involvement (N = 1), and dilated biliary ducts in the affected liver lobe (N = 1).

The result of the classification of the cysts based on the initial sonography descriptions and the archived images is displayed in Table 2.

Table 2.  Type of cyst, location, classification, type of treatment, and outcome for all patients Thumbnail image of

Diagnostic Confirmation

Serology results were available for 25 of 26 patients, Table 2.

Imaging performed was CT in 1 patient, US in 10 patients, and combined US and CT in 15 patients.


Nine patients underwent PAIR as a first choice treatment. The cysts were staged as: CE1 (N = 1), CE2 (N = 2), CE3A (N = 4), CE3B (N = 3).

Five patients had no complications associated with the procedure or recurrence of cysts [stages CE1 (N = 1), CE2 (N = 1), CE3A (N = 3)], two had recurrence of cysts (stages CE3A, CE3B), and two had complications related to the procedure [subcutaneous abscess (stage CE2) and intraperitoneal spillage resulting in acute surgery (stage CE3B)], Table 2.

Three patients underwent PAIR secondary to surgery; of these, two had no complications resulting from the procedure or recurrence of cysts (stage CE1 and CE2), and one had recurrence of the cyst (stage CE2).

Thus, 7 of 12 PAIR treatments were successful (58%), ie, disappearance of the cyst(s) or, if still present, US classification as inactive.


Nine patients underwent surgery as a first choice treatment due to communication of the cyst with the biliary system or anatomical location of the cyst preventing access by PAIR (location behind stomach). In one patient, surgery was performed secondary to PAIR, due to spillage of cyst material to the peritoneal cavity during PAIR. Of the 10 patients who underwent surgery, 2 had recurrence of cysts due to non-radical surgery (N = 2) and spillage to the peritoneal cavity (N = 1).

Thus surgery was successful in 7 of 10 patients (70%) using the same criteria as for PAIR.

The difference in success rates for PAIR and surgery was not statistically significant (p = 0.67).

Medical Treatment

Seven patients received medical treatment as their only treatment. Their cysts were at stages CE1 (one patient lost to follow-up), CE4 (N = 3), and CE5 (N = 3), respectively. Treatment was initiated due to persistent symptoms.

All patients, except one (Patient 18), received pharmacological treatment with albendazole in a dose of 400 mg twice daily if the drug was well tolerated. However, the cumulative duration of the medical treatment was not standardized and varied between 6 weeks and 15 months, depending on response to treatment. In all patients undergoing PAIR or surgery, albendazole was initiated 2 weeks before the procedure and continued for 4 weeks post-procedure. Discontinuation was prompted by consolidation of cyst on imaging.

Reported side effects to albendazole were dizziness (N = 1), discomfort (N = 1), nausea (N = 1), abdominal pain (N = 1), and hair loss (N = 1).


The median duration of hospital admission after PAIR was 1 day (range 1–21 d) and after surgery 12 days (range 6–22 d).

The median follow-up for PAIR-treated patients per March 1, 2010 was 33 months (interquartile range 13–57 mo). However, seven patients are still assessed in the outpatient clinic due to other unrelated symptoms. For surgically treated patients, the median follow-up was 27 months (interquartile range 16–43 mo). Three patients are still assessed in the outpatient clinic due to other unrelated symptoms.

Patients are usually followed up for at least 2 years after treatment.


Our study is the first to review clinical practice for CE in Denmark, where surgery, medical treatment, and PAIR are all available treatment options.

The current recommendations from WHO are that stages CE1 and CE3A are appropriate for PAIR.5 PAIR is contraindicated at stages CE4 and CE5 because these are inactive stages of the infection, where treatment is unnecessary unless the cysts are complicated. It remains debatable whether PAIR should be recommended for WHO stages CE2 and CE3B. A recent retrospective study6 reported unsuccessful outcome of PAIR in 20% of 77 cysts, which were in majority WHO stages CE2 and CE3B.

In our study, PAIR was performed at CE stages CE1-CE3B, the majority being at stages CE1 and CE3A. However, also stages CE2 and CE3B were punctured, in contrast to standard WHO recommendations (see above). This may be due to an inaccurate retrospective classification.

Importantly, the median duration of hospital admission after PAIR was shorter than after surgery.1,3,7

In another recent large prospective long-term study,8 a modified technique of PAIR, D-PAI (double percutaneous aspiration and injection of ethanol in the cyst cavity without re-aspiration) was performed on 151 viable (stages CE1, CE2, and CE3) CE cysts. The authors reported excellent results, with disappearance of the cysts in 48.4% of cases, solidification of cysts in 46.2% and liquid component (but inactivity of CE cysts) in 5.3% of patients. Surprisingly, they did not classify WHO CE3 cysts into CE3A or CE3B cysts. A third study recently reported failure of PAIR in CE2 and CE3b cysts.9

Seven patients received albendazole as their only treatment. Except for one patient (drop-out) all cysts were inactive on initiation of medical therapy (stages CE4 and CE5). For these patients albendazole treatment had been started based on a positive serology and clinical symptoms in spite of sonographic appearance (CE4 and CE5) that would not normally prompt medical treatment. As this is a retrospective study, it is important to underline that the clinicians have not been uniformly guided by the ultrasound stage of the CE cysts.

The efficacy of albendazole treatment administered alone is unclear. A recent systematic review of albendazole treatment of 1,159 CE cysts suggested an effect for active CE1 cysts but further studies are needed.10 It has previously been attempted to add praziquantel—a medicament primarily used for schistosomiasis—to albendazole to enhance its scolicidal effect, although there is still insufficient evidence to recommend it as adjuvant treatment.11

Treatment with mebendazole and albendazole tends to fail at stages CE2 and CE3B.10,12

Our patients were generally treated and followed up in the outpatient clinic for at least 2 years even when considered cured for CE at an earlier stage. We included the follow-up time in the total treatment period for each patient, thus the true duration of effective treatment and follow-up may be overestimated and should be interpreted with caution. A longer follow-up is recommended by experts.5

The main limitations of our study are caused by the retrospective nature and the limited number of patients available. Medical treatment, patient history, and reported duration of symptoms were not reported in a standardized manner in the medical records. Importantly, not all the cysts included in this study had been classified prospectively according to the WHO-IWGE classification. This is a notable limitation as the recently proposed WHO-IWGE classification has important implications for prognosis and choice of treatment.5

As there are no clinical trials comparing all treatment modalities side by side, it is still unclear which treatment would be the best option, but regarding efficacy, the mere fact that PAIR and surgical patients were hospitalized for 1 and 12 days respectively points at PAIR as the primary choice, when possible. A useful summary of recommendations according to stage and type of CE for the different treatment modalities is available in recent reviews.5,13

CE is a rare disease in Denmark with most patients being immigrants. We recommend that current international recommendations for staging and treatment be adhered to in a prospective manner, so that outcome may be optimized for patients with CE.


We thank Brunetti et al. for Figure 1.

Declaration of Interests

The authors state they have no conflicts of interest to declare.