Case of hepatic alveolar echinococcosis | Journal of MEDICAL SCIENCES

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https://doi.org/10.53453/ms.2023.11.6

Case report of hepatic alveolar echinococcosis

Ugnė Janonytė

, Gabriela Gerasimovič

, Vytautas Kiudelis

Lithuanian University of Health Sciences, Faculty of Medicine, Kaunas, Lithuania

Hospital of Lithuanian University of Health Sciences, Department of Gastroenterology, Kaunas, Lithuania

Abstract

Background. Hepatic alveolar echinococcosis (HAE) is a parasitic disease, caused by Echinococcus multilocularis.

HAE may be a challenging diagnosis, as it often resembles a malignant liver lesion upon initial investigation.

Diagnosis of HAE as a malignancy may result in surgical overtreatment or progression to a stage in which resection

may no longer be available and in some cases critical delay in growth-inhibiting benzimidazole treatment.

Case presentation. We present a case of HAE and its differential diagnostic work-up from cholangiocarcinoma

(CCA), with thorough radiological work-up being the primary diagnostic tool. Our patient, a 65-year-old male was

admitted to the emergency department (ED) with complaints of pruritus and jaundice. An abdominal ultrasound (US)

performed in the ED revealed an irregular heterogeneous necrotic mass. Laboratory work-up showed conjugated

hyperbilirubinemia, slightly elevated liver transaminases and significantly increased cholestatic markers. Following

this, the patient was transferred to the gastroenterology department. A contrast-enhanced chest abdomen-pelvis

computerized tomography (CT) scan was performed. The images detected a tumorlike heterogeneous hepatic mass

with a liquefied necrotic area. Abdominal US ruled out cholangiocarcinoma (CCA) and a positive anti-echinococcus

IgG antibody test confirmed the diagnosis of HAE. After alleviating obstructive cholestasis with biliary stenting using

endoscopic retrograde cholangiopancreatography, treatment with albendazole was initiated and the patient was

discharged. At 1 month follow-up, cholestatic serum markers had improved with no reported side effects of

anthelmintic treatment.

Conclusion. Despite diagnostic and treatment innovations, HAE still causes high mortality in the Baltic region. Thus,

gastroenterologists should be aware of the relevance of HAE as a differential diagnosis in infiltrating liver lesions.

Keywords: hepatic alveolar echinococcosis, echinococcus multilocularis, case report, ultrasonography, computerized

tomography, cholangiocarcinoma.

Journal of Medical Sciences. 23 Nov, 2023 - Volume 11 | Issue 6. Electronic - ISSN: 2345-0592

Medical Sciences 2023 Vol. 11 (6), p. 45-52, https://doi.org/10.53453/ms.2023.11.6

1. Introduction

Hepatic alveolar echinococcosis (HAE) is a

parasitic disease, caused by Echinococcus

multilocularis (E. multilocularis) [1]. Humans

contract echinococcosis by petting or handling

infected animals (e.g. fox, wolf, raccoon dog) or

ingesting food contaminated with their faeces [2].

In one study, E. multilocularis was detected in 58.7

% of red foxes examined in various areas of

Lithuania [3]. Despite diagnostic and treatment

innovations, HAE still causes high mortality in the

Baltic region. From 1997 to 2013, the survival in

35.4 % of registered HAE cases in Lithuania was

less than one year from initial diagnosis, due to the

advanced stage of the disease [4]. Moreover, HAE

may be a challenging diagnosis, as it often

resembles a malignant liver lesion upon initial

investigation, which may lead to an inappropriate

treatment strategy [5]. We present a case of HAE

and its differential diagnostic work-up from

cholangiocarcinoma (CCA).

2. Case presentation

A 65-year-old man was admitted to the emergency

department (ED) with complaints of pruritus and

jaundice. The patient noted passing putty-coloured

stools and decreased appetite, having lost about 2

kg during a couple of weeks. During physical

examination, no abdominal symptoms were

observed. The patient had no previous history of

liver disease or other underlying conditions. An

abdominal ultrasound (US) in the ED revealed an

irregular heterogeneous mass with a large area of

necrosis, peripheral hyperechogenicity and dilated

biliary tree. Laboratory work-up showed

conjugated hyperbilirubinemia, slightly elevated

liver transaminases and significantly increased

cholestatic markers (Table 1).

Table 1. Laboratory blood analysis with signs of cholestasis.

Laboratory analysis

Parameter

Value

Reference value

Total bilirubin

241.98 μmol/L

5-21 μmol/L

Direct bilirubin

145.01μmol/L

0-3,4 μmol/L

Alanine aminotransaminase

75.0 U/L

1-50 IU/I

Aspartate aminotransferase

84.0 U/L

1-50 IU/I

Alkaline phosphatase

621.0 U/L

30-120 IU/I

Gamma-glutamyl transferase

781.0 U/L

1-39 I/UI

Following this, the patient was transferred to the

gastroenterology department. A contrast-enhanced

chest abdomen-pelvis computerized tomography

(CT) scan was performed. The images detected a

tumorlike heterogeneous hepatic mass, infiltrating

the hilum and right liver lobe, where it had formed

a liquefied necrotic area (Figure 1).

To differentiate between HAE lesion and CCA, a

throughout abdominal US was performed. The

pseudocyst pattern located in the right liver lobe,

containing ~1460 ml of liquid, supported the high

possibility of echinococcus parasitic tissue

(Figure 2).

Journal of Medical Sciences. 23 Nov, 2023 - Volume 11 | Issue 6. Electronic - ISSN: 2345-0592

Figure 1. Contrast-enhanced CT reveals

heterogeneous hepatic mass infiltrating the hilum

and right liver lobe (15.7 × 13.4 × 16.7 cm).

Figure 2. The abdominal US showcases a

pseudocyst with a large area of central necrosis

surrounded by an irregular region of

hyperechogenicity representing fibrous tissue

(15.9 × 15.7 cm).

Biopsy of the lesion was avoided due to the

possible spread of echinococcosis. An

immunoserologic analysis for anti-echinococcus

IgG antibody came back positive, supporting the

diagnosis. According to clarified environmental

anamnesis, the patient is an agricultural worker

and noted having contact with non-domesticated

red foxes two years before current hospitalization.

The patient's further treatment plan was discussed

by a multidisciplinary team. It was decided that the

formation was too large for successful radical

surgical resection. After alleviating obstructive

cholestasis with biliary stenting using endoscopic

retrograde cholangiopancreatography, treatment

with albendazole 400 mg twice daily was initiated

and the patient was discharged.

During a follow-up after a month, the patient

reported no abdominal symptoms or other side

effects (e.g. toxic hepatitis) of anthelmintic

treatment. Moreover, a blood work-up revealed

markedly improved bilirubin and liver enzyme

levels. Thus, a choice to continue the treatment

with albendazole for at least two years was made.

3. Discussion

Diagnostic strategy. The diagnosis of HAE is

based on the patient's clinical-epidemiological

history, radiological imaging, serologic and

histopathologic analyses [6]. At least two of the

following findings are needed to confirm a case of

HAE: 1) typical lesion pattern confirmed with

imaging; 2) positive Echinococcus spp. serologic

test; 3) E. multilocularis histopathologic features;

and 4) E. multilocularis DNA identification in a

clinical specimen [7].

The main method of HAE diagnosis is radiological

imaging, while serologic examination

(Echinococcus spp. and E. multilocularis IgG

ELISA) is used to support the diagnosis or rule it

out [8]. In cases of ambiguous radiological and

serological test results, percutaneous fine needle

aspiration (FNA) biopsy may be considered [9].

However, it is not usually recommended due to the

potential spread of daughter cysts. In rare cases of

FNA, prophylactic treatment with albendazole for

4 days prior to the procedure and continuation for

one month after, is recommended [10].

Ultrasonography is the initial diagnostic method of

Journal of Medical Sciences. 23 Nov, 2023 - Volume 11 | Issue 6. Electronic - ISSN: 2345-0592

HAE [11]. The World Health Organization

Informal Working Group on Echinococcosis

(WHO-IWGE) proposed an imaging classification

that groups HAE lesions into different PNM

(parasite lesion, neighbour organs, metastases)

types to help with determining further treatment

strategies [12]. E. multilocularis Ulm

classification-ultrasound (EMUC-US) distin-

guishes five different lesion patterns: hailstorm,

pseudocystic, hemangioma-like, metastasis-like

and ossification [13]. However, about 70 % of

cases present as a mixed echogenicity hepatic mass

with irregular margins, dispersed calcification foci,

and a pseudocyst with central necrosis surrounded

with a rim of hyperechogenicity [8,11]. Contrast-

enhanced ultrasonography (CEUS) is another

promising diagnostic technique, as it visualizes the

parenchymal microvasculature of HAE lesions

[14]. It is proven, that CEUS can accurately

differentiate HAE from tumors, such as CCA and

hemangiomas [14,15]. Fluorodeoxyglucose

positron emission tomography (FDG-PET) is the

recommended HAE metabolic activity evaluation

tool, as the FDG uptake in HAE lesions is higher

than in unaffected liver areas [16]. However,

previous studies report that CEUS can assess the

activity of HAE, similar to FDG-PET [17].

Magnetic resonance imaging (MRI) may provide a

more precise evaluation of the parasitic lesion [8].

However, in cases of diagnostic uncertainty and

pre-operative evaluation, computed tomography

(CT) remains the modality of choice, as it

evaluates vascular, biliary, and extrahepatic

infiltration of the mass, which is valuable when

considering lesion resectability [18]. A simplified

diagnostic algorithm is depicted in Figure 3.

Nonetheless, differentiating HAE from other

hepatic masses can be a challenging task, as many

cases are diagnosed incorrectly as CCA or other

liver malignancies [5,19]. In one study, 32.5 % of

HAE patients were initially given the wrong

diagnosis, while HAE was mistaken for CCA in

19.2 % of the cases [5]. Considering the clinical

significance of misclassifying HAE as CCA, a

scoring system based on typical features of

conventional US and CEUS has been proposed,

with the sensitivity and specificity of 80.0 % and

81.3% respectively [14]. The extensive diagnostic

examination of HAE is important, as

misclassifying it as a malignancy may result in

surgical overtreatment or progression to a stage in

which resection may no longer be available and in

some cases critical delay in growth-inhibiting

benzimidazole treatment [5,20]. Thus,

gastroenterologists should be aware of the

relevance of HAE as a differential diagnosis in

infiltrating liver lesions.

Treatment and management.

The therapeutic strategy of HAE requires a

multidisciplinary approach, as it is based on

radiological evaluation with an MRI and (or) FDG-

PET, the general status of the patient, and the

technical capabilities of the surgical department

[2]. HAE is often diagnosed in its advanced stage

and is located in the right liver lobe, involving

vascular and biliary structures. Thus, surgical liver

resection cannot be performed safely [21]. In

cases, with metabolically inactive lesions, which

are calcified and/or negative by FDG-PET "watch-

and-wait" approach can be used [2]. If the lesion is

metabolically active and considered operable, the

gold standard surgical treatment is radical

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hepatectomy combined with adjuvant albendazole

therapy for at least 2 years postoperatively [22].

Reduction surgery has been proposed as an

alternative in some advanced cases. However, it

does not appear to provide an advantage over

anthelmintic therapy alone and has worse overall

survival and progression-free survival outcomes

than radical resection [23]. Liver transplantation

(LT) may be considered for very advanced cases

with a high risk of life-threatening complications

[2]. Aydinli et al. presented their own experience

with LT for HAE patients, with the overall survival

rate being 77.8 % and the most common cause of

death – sepsis [24]. Although the prognosis after

LT for HAE is considered good, disease recurrence

remains a risk due to immunosuppressive therapy

[25]. Considering this, the WHO does not

recommend LT in patients with AE metastases [1].

Ex vivo liver resection with auto-transplantation in

end-stage HAE has been proposed as a palliative

surgical option [2]. Aji et al. evaluated this surgical

modality in a prospective study with 69 patients,

the 30-day mortality and overall mortality being

7.24 % and 11.5 % respectively [26]. If surgical

treatment is not possible, reducing the proliferation

of E.multilocularis with long-term anthelmintic

medication is recommended [2]. Albendazole is

usually chosen to treat HAE, as it has been proven

to be more efficient than mebendazole [27]. In a

study conducted by Zavoikin et al., albendazole

inhibited HAE progression in 60 % of patients with

unresectable lesions [28]. However, considering

that albendazole is only parasitostatic, further

clinical trials are needed to investigate drugs (e.g.

protease or immune checkpoint inhibitors) that

could achieve a parasitocidal effect [29].

Figure 3. Diagnostic algorithm for HAE.

Positive clinical and/or

epidemiological history

Serological tests

Ultrasonography

Typical HAE lesions

Ambiguous focal

hepatic lesions

Contrast-enhanced

ultrasound

Atypical HAE lesions

Other disease

CT/MRI

Surgical resection

Conservative treatment

FDG-PET

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Another important aspect of HAE management is

the treatment of complications, such as cholangitis,

bile duct obstruction and bacterial infection of the

necrotic cavity. The previous two are alleviated

with endoscopic bile duct lavage/stenting and

percutaneous drainage [2].

The recommended follow-up after diagnosis and

initiation of albendazole is at 1, 4, and 12 weeks for

the first 3 months. Then, every 3 months for the

first year and every 6 months for the second year.

The assessment should include abdominal US,

complete blood count, transaminases,

E.multilocularis serology, and albendazole

sulfoxide (an active metabolite of albendazole)

[30]. FDG-PET is performed at the end of the

second year. However, anthelmintic treatment can

only be withdrawn after two negative FDG-PET

and E.multilocularis serology results [2,30].

4. Conclusions

HAE is a zoonotic parasitic infection primarily

affecting the liver. Treatment strategy of HAE

mainly consists of three options: (1) surgical

approach (resection or transplantation) with

combination albendazole therapy, (2) long-term

monotherapy with albendazole, and (3) alleviation

of possible complications. However, surgery is

often deemed unsafe, as HAE tends to be

diagnosed in an advanced stage. Moreover, due to

diagnostic challenges, HAE is quite often

misinterpreted as a malignancy. Thus, a high

degree of clinical suspicion needs to be

maintained, especially in endemic areas and a

thorough investigation should be performed. A

detailed patient history, radiological work-up and

serology are the primary diagnostic tools with

histology being reserved for the more challenging

cases.

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