WHO Informal Working Group. International classification of ultrasound images in cystic echinococcosis for application in clinical and field epidemiological settings

Hydatid cysts in muscle: a modified percutaneous treatment approach

INTRODUCTION

Any organ in the human body may be affected by hydatid disease, but the liver and the lungs are most commonly affected. A rare localization of hydatid disease is within muscle tissue. Herein we present three patients with muscular hydatid disease who were successfully treated with a modified percutaneous approach.

METHODS

Patients with Gharbi type III cysts were treated on an outpatient basis. All procedures were performed under ultrasound guidance in the ultrasonography unit of our department. After local anesthesia, percutaneous puncture was performed in a one-step procedure. After free drainage stopped, absolute ethanol and polidocanol were injected into the cyst cavity. After the procedure, the patient was observed for at least six hours for any adverse reactions and sent home. Patients were followed-up with ultrasonography. A positive treatment effect was characterized by a reduction of the cyst's pseudo-tumor pattern and size, and by detachment of the germinal membrane.

RESULTS

The three patients in this report had a total of five hydatid cysts in muscle tissue and were all successfully treated with a modified percutaneous approach without recurrence.

CONCLUSION

Percutaneous drainage without re-aspiration is simple, easy to apply, low cost, repeatable, and does not require hospitalization. There have been no reported deaths associated with the procedure and morbidity is very low. When the technique is applied properly, relapses do not occur. With its low complication rate and its suitability for outpatient treatment, this method can be an alternative to surgery or puncture, aspiration, injection, and re-aspiration (PAIR) in selected patients.

A case of hydatid cyst associated with postpartum maternal death

A young, apparently healthy woman from a rural area in South Africa presented in the third trimester of pregnancy with a symptomatic abdominal mass between the uterine fundus and liver. The etiology was established to be an echinococcus cyst of the liver and medical treatment was initiated. The fetal outcome was good but the mother died 3 days postpartum due to an unusual but devastating complication of the hydatid cyst.

Post-survey follow-up for human cystic echinococcosis in northwest China

In Hobukesar, Xinjiang Uygur Autonomous Region, (China), a mass-screening programme for human cystic echinococcosis (CE)was performed during 1995 and 1996. After the survey 51 cases were followed-up using ultrasound scan and serology for 1-8 years(1996-2003). These included 20 CE cases treated by surgery (endocystectomy), four CE cases treated by percutaneous drainage(PAIR), six untreated CE cases, five ultrasound 'query' cases, eight cases of isolated hepatic calcifications, four previous CE surgery cases whose ultrasound was now normal, and four seropositive cases who exhibited a normal hepatic ultrasound. Follow-up results indicated that in the untreated CE patients, one case exhibited a spontaneous cure within 4 years, another case changed from a hepatic hydatid cyst that contained a floating laminated membrane (type CE3) to a cyst that contained daughter cysts (type CE2)within 1 year of follow-up. In the 20 surgically treated cases, two recurrent CE cases occurred within 4 years, and five cases had had residual cavities for more than 4 or 8 years. Of the 4 PAIR treated cases, two recurrent cases of CE occurred within 4 or 8 years of follow-up. Serological follow-up data showed that specific IgG antibody levels were persistently positive in most CE cases, but exhibited a decreasing tendency in cases that were effectively treated by surgery; In contrast, serum IgG levels in the PAIR group or in the recurrent CE cases after surgery exhibited an increasing tendency. At least one persistent seropositive case with an isolated hepatic calcification was considered to be abortive CE.

Late ultrasonographic findings in cases operated for hydatid cyst of the liver

PURPOSE

The aim of this study was to evaluate and present the images due to surgical intervention and to recurrences in patients who had been operated for hydatid cyst of the liver at least 12 months prior to the imaging process.

MATERIAL AND METHODS

A total of 77 patients (46 females, 31 males) with a mean age of 38 years (10-60 years) who had undergone surgical intervention for hydatid cyst of the liver were included in this study. The type and the number of operations were determined by reviewing previous medical records of the patients. Recurrence findings and postoperative images were examined by ultrasonography in all patients.

RESULTS

Of the 77 patients, 68 had undergone surgical operation for hydatid cyst of the liver for once, six cases for twice, one patient for three and another patient for four times. Ultrasonographic examination was considered normal in 9 (11.6%) patients. The most frequent finding in the remaining patients was hypoechoic (n=6) and anechoic (n=14) images with a hyperechoic periphery within the operation area. While a coarse heterogenous area was visualized in 12 cases (15.5%), a sole hypoechoic image was present in 10 patients. Recurrence was detected in 9 (11.6%) patients of whom 7 were asymptomatic. While daughter cysts were detected in two recurrent cases; the remaining were unilocular cysts. An omentum image extending to the operation area was detected in 11 patients. Calcification was present in 14 patients, whereas four cases had less common findings of anechoic tubular structures adjacent to the operation area.

CONCLUSION

While the liver may seem normal by ultrasonography in the late postoperative period in patients, who had been operated for hydatid cyst of the liver, various images may also be present. These images may be misinterpreted as recurrence or other pathologies. Thus, the radiologist should be familiar with the postoperative ultrasonographic findings of hydatid cyst and should not misinterpret the image of anechoic fluid as recurrence. When in doubt, ultrasonographic follow-up is essential. An early postoperative ultrasonographic examination may be the key point in precluding a misdiagnosis.

Hydatid disease in acute leukemia: effect of anticancer treatment on echinococcosis

Echinococcosis, also known as hydatid disease or hydatidosis, is a zoonotic illness caused by the larval form of Echinococcus spp. It is highly prevalent in areas where the parasite is endemic such as the Mediterranean region. However, occurrence of echinococcosis and cancer together is rare. We treated and followed approximately 1200 patients with different hematologic neoplastic diseases between 1985 and 2003, and only one of these individuals had concomitant acute leukemia and liver hydatidosis. This report describes the case of a 19-year-old man who had both primary refractoriness of acute leukemia (AML-M4) and liver hydatidosis. Management is discussed. The patient had cystic echinococcosis (CE) of the liver that was classified as CE1 according to the system established by the World Health Organization's Informal Working Group on Echinococcosis. The patient underwent 3 months of treatment with agents that targeted the leukemia (daunorubicin, idarubicin, cytarabine, fludarabine) and its complications (amphotericin B, amphotericin B lipid complex, liposomal amphotericin B). Throughout this period, the size and the contents of the cyst did not change, Echinococcus titers remained unchanged, and the cyst classification remained CE1.

Progress in diagnosis, treatment and elimination of echinococcosis and cysticercosis

Here I review the current status of geographical occurrence and public health significance of echinococcosis (Echinococcus spp. infections) and cysticercosis (Taenia solium infection) with special emphasis on the remarkable technologic progress achieved in recent decades that has led to greater understanding of the biology and epidemiology of these cestode infections. The greatest remaining challenges are to apply this knowledge and technology to improved medical management and prevention of these infections.

Cystic echinococcosis of the liver associated with repeated international travels to endemic areas

Cystic echinococcosis (CE) is increasingly seen in immigrants from endemic areas to Western countries; however, it is rarely reported in short-term travels to endemic areas. This is partly because the echinococcal cyst typically grows slowly and may long remain clinically silent. We describe a case of cystic echinococcosis in a man born and living in a nonendemic urban area in North Italy that was acquired during a period of frequent travels in highly endemic countries.

Echinococcal disease in Alberta, Canada: more than a calcified opacity

Background

Most cases of echinococcal disease (ED) acquired in Canada are thought to be due to the sylvatic form of Echinococcus granulosus, which may be more benign than ED due to either Echinococcus multilocularis or the pastoral form of E. granulosus. There are limited descriptions of the clinical course and outcome of Canadian patients with ED in the modern era.

Methods

A retrospective chart review was performed of patients hospitalized with echinococcal disease (ED) from 1991 to 2001 in Edmonton, Alberta.

Results

Forty-two cases of ED were identified of which 19 were definite, 3 probable, and 20 possible. Further analysis was limited to the 22 definite and probable cases, of which 77% were female and 41% aboriginal, with an age range of 5 to 87 years. Nine patients (40%) had pulmonary involvement and 11 (50%) hepatic involvement. One patient had an intracardiac mass presenting as a cerebrovascular event and one had a splenic cyst. Seven of the 22 patients had combined surgical resection and medical treatment, six had surgical resection of the cyst alone, four had cyst aspiration, one had medical treatment alone and four had no specific treatment. There was no mortality attributable to ED but three patients died of unrelated illnesses.

Conclusion

Echinococcal disease in northern Alberta has a marked diversity of clinical presentations, and generally has a good prognosis despite a wide variety of therapeutic interventions.

Screening for cystic echinococcosis in an endemic region of Peru using portable ultrasonography and the enzyme-linked immunoelectrotransfer blot (EITB) assay

Cystic echinococcosis (CE) caused by the larval form of Echinococcus granulosus is a major public health problem in sheep-raising regions of the World. This study compared portable ultrasound with the enzyme-linked immunoelectrotransfer blot (EITB) assay as screening methods to estimate the prevalence of human CE in a remote village in the Peruvian Andes. Three hundred eighty-nine villagers were examined by portable ultrasound and blood samples were drawn by venipuncture. Sera were collected and tested for antibodies against CE using an EITB assay. Cystic lesions were classified based on their ultrasound morphologic characteristics. The prevalence of human CE using portable ultrasound and the EITB assay were 4.9% and 2.6%, respectively. Fifty-three percent of subjects with CE were EITB positive. Portable ultrasound was well received by the community, augmented CE detection and allowed a faster estimate of human infection than the EITB assay.

Primary hydatid cyst in the anterior thigh: Sonographic findings

Hydatid cysts rarely involve the musculoskeletal system. We present the case of a 23-year-old man with a primary hydatid cyst between the femur and the quadriceps muscle in his left thigh. No cysts were located in the adjacent femur or quadriceps muscle. Cyst resection with sparing of the surrounding muscles, combined with anthelmintic therapy, was curative. In regions where hydatidosis is endemic, hydatid cysts should be included in the differential diagnosis of any unusual soft-tissue swelling.

Epidemiology, clinical manifestations and diagnosis of zoonotic cestode infections: an update

This paper reviews the literature on zoonotic cestode infections with specific reference to the years 1999-2003. The sources and prevalence of various zoonotic tapeworm infections caused by adult and larval stages of the genera Taenia, Echinococcus, Diphyllobothrium, Hymenolepis and Dipylidium continue to be an important cause of morbidity and mortality, not only in most underdeveloped countries but also in industrialized countries, particularly in rural areas or among immigrant groups from endemic areas. The review gives a detailed report on recent molecular epidemiological studies on the taxonomy and phylogenetic variations in Echinococcus granulosus, immunological tests and imaging techniques used in epidemiological surveys and clinical investigations of important adult and larval tapeworm infections of animals and humans. Larval stages or metacestodes of Taenia solium, Echinococcus spp. and pseudophyllidean tapeworms (Spirometra syn. Diphyllobothrium spp.) may reside in various tissues of their intermediate hosts, including humans. In particular, Cysticercus cellulosae (T. solium) and the larvae of E. granulosus, and E. multilocularis, which are predominantly located in the liver, lungs and central nervous system forming various types of cysts, lead to a complex of systemic diseases such as cysticercosis, cystic echinococcosis and alveolar echinococcosis, respectively. Relatively rare clinical manifestations are seen in the muscles, subcutaneous tissue, spleen, kidneys, bones and body cavities.

Ultrasound in tropical and parasitic diseases

CONTEXT

Migration and worldwide travel mean that western clinicians and radiologists more and more face imported tropical diseases. Diseases with unclear signs and symptoms are likely to be investigated with ultrasound. Many tropical diseases have particular ultrasonographic features that are not familiar to the examiner and which may lead to further unnecessary or even harmful diagnostic investigations. In developing countries, ultrasound machines are becoming more widely distributed and are fairly cheap. Portable devices allow field use of ultrasound for population studies and individual diagnosis of tropical diseases.

STARTING POINT

Recently, WHO introduced a standardised classification of ultrasonographic images of cystic echinococcosis (Acta Trop 2003; 85: 253-61), to obtain comparable results in patients worldwide and to link disease status with each morphological type of echinococcosis cyst. WHO also defined guidelines for the puncture, aspiration, injection of ethanol, and re-aspiration of such cysts. Ultrasound allows diagnosis of schistosomiasis-induced periportal fibrosis and bladder abnormalities. Liver abscesses can be differentiated from other focal lesions such as cysts or neoplasms. For amoebic abscesses, invasive procedures are usually not required. In doubtful cases ultrasound-guided puncture can give adequate material for microscopy and culture. Helminths (eg, ascaris), flukes, and filariae can be seen directly with ultrasound. Filaria-induced damage also includes hypoechogenic splenic foci and ultrasonographic abnormalities due to tropical hypereosinophilia. WHERE NEXT? Classification of cysts and procedures that are less invasive than conventional surgery are being developed further for cystic echinococcosis. Novel methods are needed for the assessment of polycystic and alveolar echinococcosis. Ultrasound protocols for schistosomiasis are being evaluated for interobserver reliability, relation to clinical disease status, and power to predict complications. A WHO expert-group is also developing a standardised protocol for Asian schistosomiasis. International consensus on an algorithm for managing amoebic liver abscesses is needed.

Performance characteristics and quality control of community based ultrasound surveys for cystic and alveolar echinococcosis

The probability of disease given the results of a test, is called the predictive value of the test. The predictive value of a test is not a property of the test itself but will vary according to the prevalence of the disease in the studied population. The positive predictive value (PPV) is the probability that the subject tested has the disease given that a positive result is obtained. The negative predictive value (NPV) is the probability that the subject tested is normal given that a negative result is obtained. As the prevalence of a disease in a population approaches zero so does the PPV and most of the positive cases will be 'false positives'. Conversely the NPV will be very high at low prevalences and there will be few 'false negative' results. The sensitivity and specificity of a test are properties of the test and do not vary with prevalence. The higher the sensitivity and specificity of a particular test the greater the predictive values will be at any given prevalence of the disease. Ultrasound (US) is increasingly used for detecting lesions due to cystic and alveolar echinococcosis (CE and AE) and portable US scanners facilitate community based mass screening surveys in remote rural communities. Screening is justified with AE and CE in endemic areas as diagnosis at an early stage can lead to a better prognosis following treatment. The sensitivity and specificity of US has been reported to be between 88-98% and 95-100% respectively for CE and the sensitivity is a little higher for AE. Both species have pathognomonic signs on US and the technique is considered to be the 'gold standard' although it is still an imperfect test. Clinical, laboratory and epidemiological data also play an important role in the diagnosis of CE and AE. US results where possible, should be evaluated in relation to these findings. Suspected CE and AE images, may benefit from the use of other imaging techniques such as magnetic resonance imaging, computerised tomography and in the case of AE angiography or cholangiography. Immunological tests or molecular biological techniques also provide a useful back up, especially for AE. As sensitivity and specificity are properties of the US diagnostic test they should not vary if the case mix reported in different studies remains the same. The use of the WHO standardised US classifications for CE and AE should be used so that the properties of the test are standardised. Quality control of field based studies will depend on geographical variations in the case mix and the relative proportions of cyst types without pathognomonic signs. The latter will have the most bearing on variations in specificity, as would the use of different classifications. Inter- and intra-observer variability and differences in prevalence will affect the performance of US in different endemic settings. Community based surveys must adhere to the highest ethical standards and the outcome of surveys should result in appropriate treatment and follow-up strategies for all infected individuals and suspected cases found during the surveys.