Hepatic cystic echinococcosis (type II): A case report

Abstract

This article presents a case report of a rare instance of hepatic cystic echinococcosis (Type II). The patient is a young female who has resided in the Inner Mongolia region of China for an extended period and has a clear history of contact with dogs and sheep. She presented with recurrent upper abdominal pain accompanied by jaundice of skin and sclera for 2 months. Through comprehensive clinical history inquiry, physical examination, and imaging studies such as ultrasound and computed tomography, the diagnosis of hepatic cystic echinococcosis (Type II) was confirmed. The patient underwent a capsular excision, and the postoperative prognosis was good with no recurrence or implantation during short-term follow-up. This case report details the patient’s clinical symptoms, signs, diagnostic process, and key points for differential diagnosis, emphasizing the crucial role of imaging studies in the diagnosis of hepatic cystic echinococcosis. Additionally, the treatment plan and postoperative follow-up for this case are discussed, aiming to provide a reference for clinical diagnosis and treatment of hepatic cystic echinococcosis.

Introduction

Hepatic cystic echinococcosis (HCE) is a parasitic disease caused by the larval stage (echinococcosis) of the Echinococcosis granulosus tapeworm residing in the liver. ¹ The prevalence of HCE varies geographically, being more common in areas where livestock farming is prevalent, particularly in the northwest of China. In China’s western regions, the average prevalence of HCE is 1.08%, with some areas of the Qinghai-Tibet Plateau having a prevalence rate as high as 6%. The disease can affect people of all age groups, but it is more common in women.^2,3 Since the symptoms of HCE and hepatic alveolar echinococcosis (HAE) are easily confused, Table 1 shows the main differences between them. This disease is classified into various types based on the parasitic state of the echinococcus within the liver and the resulting pathological changes. Among them, HCE (Type II) specifically refers to the formation of large, solitary or multiple cysts in the liver by the echinococcus, which can be accompanied by severe complications such as cyst enlargement, rupture, infection, and compression of surrounding organs.^4,5

Table 1.

The main differences between HCE and HAE. ³

Characteristic	HCE	HAE
Causative agent	E. granulosus	E. multilocularis
Morbidity	(1∼200)/100,000	(0.03∼1.2)/100,000
Clinical presentation	Hydatid compression, rupture, and infection can lead to complications of hypersensitivity, disseminated implantation, and septic shock	Invasion of the biliary tract leads to obstructive jaundice; invasion of blood vessels leads to portal hypertension and liver stasis

HAE: hepatic alveolar echinococcosis; HCE: hepatic cystic echinococcosis.

The case reported in this article is a typical example of HCE (Type II). Its unique clinical presentation, diagnostic process, and therapeutic challenges not only deepen our understanding of this disease but also provide valuable experience for clinical diagnosis and treatment.

Case presentation

The patient was admitted to the Xilingol League Central Hospital on 13 April 2024. Two months before admission, the patient experienced upper abdominal pain without any apparent cause, manifesting as intermittent distending pain that worsened intermittently. The pain radiated to the right shoulder and back, accompanied by skin and sclera jaundice. The patient suspected gastric discomfort and received symptomatic treatment at a local clinic, resulting in improvement of the condition. However, the patient subsequently experienced recurrent epigastric pain with similar characteristics and jaundice, prompting a visit to a hospital for further treatment. Upon examination at the outpatient department, the patient was admitted with a diagnosis of “hepatic space-occupying lesion; HCE; obstructive jaundice.” Surgical and trauma history: The patient underwent surgery (specific details unknown) for HCE 24 years ago. Physical examination revealed jaundice of skin and sclera, postoperative scars visible on the abdomen, soft abdomen, positive epigastric tenderness, negative rebound tenderness, no abdominal muscle tension, and negative Murphy’s sign.

Laboratory test results were as follows: Blood routine examination: C-reactive protein: 51.48 mg/L; coagulation panel: plasma prothrombin time: 15.3 seconds, prothrombin activity: 63%, international normalized ratio (INR) of prothrombin: 1.29 INR, activated partial thromboplastin time: 37.4 seconds, fibrinogen: 5.99 g/L. Urine routine examination: white blood cells: (+), bilirubin: (++), ketone bodies: (+), carbohydrate antigen 19-9: 6957.00 U/mL. Biochemistry: alanine aminotransferase: 148 U/L, aspartate aminotransferase: 158.4 U/L, total bilirubin: 128.8 μmol/L, direct bilirubin: 110.6 μmol/L, indirect bilirubin: 18.2 μmol/L, albumin/globulin: 1.18, lactate dehydrogenase: 312.0 U/L, α-hydroxybutyrate dehydrogenase: 225.0 U/L, alkaline phosphatase: 298.0 U/L, amylase: 885.0 U/L.

Imaging examination results were as follows: Color Doppler ultrasonography of the liver, gallbladder, pancreas, and spleen: HCE (Type II), cholecystitis with bilateral gallbladder wall sign, thickened echo in the tail of the pancreas (please refer to clinical findings), splenomegaly, widened splenic portal vein, pelvic effusion. As shown in Figure 1(a) and (b), abdominal computed tomography (CT) scan with enhancement: consideration of echinococcosis of the right hepatic lobe (cystic echinococcosis [CE] Type 2), secondary intrahepatic and extrahepatic biliary dilation, compression and narrowing of the inferior vena cava with obstructed venous return (please refer to clinical findings), calcified nodule in hepatic segment S3, considered echinococcosis (CE Type 5). As shown in Figure 1(c), magnetic resonance cholangiopancreatography: hepatic space-occupying lesion, possible echinococcosis; lesion compressing the bile duct in the hepatic hilum, left hepatic duct, and its branches with displacement, secondary dilation of intrahepatic bile ducts in the left hepatic lobe, local dilation of bile ducts in the posterior right lobe, widened periportal space in the left lobe. As shown in Figure 1(d), 3-dimensional imaging: suggesting a space-occupying lesion in the right hepatic lobe.

Figure 1.

Imaging examination. (a–b) Computed tomography scan. The red arrows mark HCE lesions. (c) Magnetic resonance cholangiopancreatography. The red arrow marks the bile duct compressed by the HCE lesion and (d) 3-dimensional imaging. The red arrow indicates the left branch of the portal vein. The lesion compresses the hepatic hilum, causing the intrahepatic bile duct, left and right hepatic arteries, and portal vein to deviate from their original anatomical positions. HCE: hepatic cystic echinococcosis.

The diseases that need to be primarily differentiated from HCE are as follows: 1. Hepatic cyst: Congenital hepatic cysts have thinner cyst walls, while those of HCE are relatively thicker. Patients with hepatic cysts generally do not have a history of living in endemic areas, whereas patients with HCE often have relevant experiences of living in endemic regions. CT scans of hepatic cysts show round or quasi-round low-density shadows in the liver with clear boundaries and uniform density, with CT values close to the density of water. CT scans of HCE are mostly round or quasi-round, and polycystic types may show multiple cysts of varying sizes arranged in a honeycomb or grape-like pattern, thus ruling out hepatic cysts. 2. Hepatic abscess: Patients with hepatic abscesses usually present with obvious inflammatory symptoms such as high fever, chills, and severe pain in the liver area. However, patients with HCE generally do not exhibit these typical inflammatory symptoms. On imaging examinations, the pus in hepatic abscesses appears different from echinococcal cyst fluid on ultrasound and other examinations, and the abscess wall also has its characteristics, usually being thick and irregular, with surrounding liver tissue possibly showing edema and other manifestations, thus ruling out hepatic abscesses.

The patient presented with upper abdominal pain accompanied by skin and sclera jaundice upon admission. Physical examination revealed positive tenderness in the upper abdomen. Biliary obstruction was suspected. After comprehensive consideration, an endocystectomy was performed to relieve the compression and improve liver function. After significant improvement in liver function, surgery was scheduled on 19 April 2024. Considering the long duration of oral albendazole treatment and the possibility of disease progression, surgery was performed first, followed by oral albendazole treatment after surgery. During the surgery, 20% hypertonic saline was used to protect the surgical area, and the residual cavity of the hydatid cyst was inactivated for 30 minutes. Before implementing all treatment plans, consent was obtained directly from the patient.

The intraoperative imaging data is shown in Figure 2. During the operation, a small mass was found at the edge of the liver and was completely resected. A mass was also found in the right lobe of the liver, adjacent to the first hepatic portal, with significant compression of the portal vein. Considering the patient’s poor preoperative hepatic function, combined with the intraoperative exploration revealing significant biliary stasis in the liver accompanied by nodular changes, there was a high risk of postoperative hepatic failure. Therefore, a partial hepatectomy was performed, and the inner cyst was removed (the surgical area was protected with 20% hypertonic saline, and the residual cyst cavity was inactivated for 30 minutes). The goal was to minimize hepatic resection while achieving radical treatment. However, due to the deep location of the residual cyst cavity and incomplete exposure for observation, a residual cavity drainage tube was placed. Postoperatively, the patient experienced bile leakage from the residual cyst cavity, with 150 mL/day of bile drained through the residual cavity drainage tube. However, the patient did not experience fever, jaundice, abdominal pain, or other discomfort, and the drainage was unobstructed. Observation was continued as the bile leakage drainage tube could not be removed. On postoperative day 22, endoscopic retrograde cholangiopancreatography (ERCP), endoscopic sphincterotomy, and endoscopic biliary stent placement were performed. After the procedure, the amount of bile drained through the residual cavity drainage tube decreased to 50 mL/day, with unobstructed drainage and no discomfort. The patient was discharged with the residual cavity drainage tube in place six days after the procedure. Postoperative treatment involved oral administration of albendazole tablets with a dosage of 10–15 mg/(kg·d), taken in two divided doses (after breakfast and dinner). After three consecutive months of oral albendazole tablets, a CT scan was repeated (Figure 3), which showed no new or implanted lesions. The patient was in general good condition and did not report any significant discomfort.

Figure 2.

Intraoperative image data. The blue arrow points to a space-occupying lesion at the liver margin, which was prepared for surgical resection.

Figure 3.

Postoperative changes of hepatic echinococcosis. The surgical area, marked by the red arrow, shows patchy shadows and a small amount of gaseous shadows. No new or implanted lesions are visible elsewhere.

The postoperative pathology is shown in Figure 4. As shown in Figure 4(a), under 2× magnification, the interior of the cyst showed pink-stained unstructured material with no definite cellular components. As shown in Figure 4(b), under 4× magnification, the cyst wall tissue was visible, with hepatic tissue on one side and fibrous cyst wall on the other side, accompanied by inflammatory cell infiltration. The inner side of the cyst wall was the laminated layer of the echinococcus, presenting as a cell-free layered structure. As shown in Figure 4(c), under 10× magnification, the peripheral hepatic tissue adjacent to the cyst wall was compressed and atrophied, with proliferative granulation tissue surrounding it. Pathological diagnosis: (Partial hepatic + inner cyst) Fibrous cyst wall and inner cyst of echinococcus, consistent with the characteristics of hepatic echinococcosis based on clinical and imaging data.

Figure 4.

Pathological examination. (a) Microscopic observation under 2× magnification. The red arrow points to pink, unstructured substances within the cyst. (b) Microscopic observation under 4× magnification. The red arrow indicates the fibrous cyst wall, and the yellow arrow indicates liver tissue and (c) microscopic observation under 10× magnification. The red arrow points to hyperplastic granulation tissue, and the yellow arrow indicates atrophic liver tissue.

Discussion

Dogs serve as the definitive hosts for tapeworms. Adult tapeworms reside in the small intestines of dogs, and tapeworm adults attach to the small intestinal mucosa and later shed gravid proglottids (the final segment of the mature worm containing eggs) in the host’s feces. Dogs become infected with tapeworms by consuming the offal of infected intermediate hosts, such as sheep, thereby completing the lifecycle. Sheep act as intermediate hosts for tapeworms and become infected by ingesting grass contaminated with feces from definitive hosts (such as dogs) containing tapeworm eggs. The eggs develop into cysts and daughter cysts within the sheep. Humans can accidentally become intermediate hosts through fecal-oral transmission, such as by consuming food or water contaminated with feces containing tapeworm eggs or through direct contact while handling infected definitive hosts. The lifecycle of tapeworms is sustained because definitive hosts (dogs) consume the internal organs of infected intermediate hosts (such as sheep). Dogs play the role of definitive hosts in the tapeworm lifecycle, while sheep serve as intermediate hosts, together maintaining the lifecycle and epidemiology of tapeworms. ⁶

After invading the liver, the E. granulosus gradually develops into a cyst, whose wall is composed of keratin and host fibrous tissue containing colorless transparent or slightly yellow cyst fluid. As the cyst enlarges, it can compress the surrounding hepatic tissue, leading to hepatic dysfunction. Additionally, rupture of the cyst can cause severe consequences such as acute abdominal pain, peritonitis, and allergic reactions. ⁷ In HCE (Type II), cyst enlargement is often more pronounced, and rupture or infection is more likely to occur, triggering a series of complex clinical manifestations and complications. ⁸

The clinical manifestations of patients with HCE vary with individual differences but typically include upper right abdominal pain, abdominal distension, and appetite loss, among other digestive symptoms. When the cyst compresses the biliary tract, it can cause jaundice; compression of the portal vein can lead to portal hypertension, and rupture of the cyst can cause acute peritonitis and other acute abdominal conditions. Furthermore, due to the antigenicity of E. granulosus, some patients may experience allergic reactions such as urticaria and fever. In this case, the patient’s long-term residence in a pastoral area, clear exposure history, and typical symptoms of upper right abdominal pain and jaundice provided important clues for the diagnosis of the disease. ⁹

The diagnosis of HCE primarily relies on imaging examinations such as ultrasound, CT, and magnetic resonance imaging (MRI). Ultrasound is the preferred screening tool due to its noninvasive, convenient, and low-cost nature. CT and MRI can more clearly display the morphology, size, and location of the cyst and its relationship with surrounding tissues, which is crucial for determining the treatment plan. Additionally, serological tests such as E. granulosus antibody detection also aid in disease diagnosis. However, it is noteworthy that due to the weak antigenicity of E. granulosus, the sensitivity and specificity of serological tests are limited, and comprehensive judgment in conjunction with other clinical data is necessary. ¹⁰

The treatment of HCE aims to thoroughly remove the lesion, alleviate symptoms, prevent recurrence, and manage complications. Treatment methods include drug therapy, surgical resection, and interventional therapy. Drug therapy is primarily used for patients with milder conditions and smaller cysts but has limited effectiveness and a high recurrence rate. Surgical resection is the preferred method for treating HCE (Type II), enabling direct removal of the lesion and relief of compression symptoms. However, due to the tight adhesion of the cyst to surrounding tissues, surgery can be challenging and risky. Interventional therapies such as percutaneous puncture aspiration of cyst fluid and injection of sclerosing agents have, to some extent, compensated for the deficiencies of traditional surgery, providing patients with more treatment options.^11,12

Compared to partial radical resection for HCE, radical resection is associated with increased complexity and hospitalization costs. We found no significant difference in short-term outcomes between the two methods, indicating that partial radical resection for HCE may be a feasible alternative, especially in resource-limited settings or for patients unsuitable for more complex surgeries. ¹³

As adjuvant therapy for E. granulosus infection, pharmacological treatment can reduce preoperative lesions and prevent postoperative recurrence. Currently, benzimidazole drugs, such as albendazole, are the first-choice treatment for E. granulosus infection. However, this drug can cause significant adverse reactions and is not suitable for patients with bone marrow suppression, liver failure, or pregnancy. Patients undergoing treatment with this drug should have their blood white cell count and liver function indicators checked monthly to promptly address any adverse reactions. ¹⁴

Conclusion

In summary, HCE (Type II), as a parasitic disease with pronounced regionality and diverse clinical manifestations, poses numerous challenges in both diagnosis and treatment. By thoroughly understanding its epidemiology, pathophysiological basis, and clinical manifestations, combined with advanced diagnostic techniques and comprehensive treatment plans, we can better control the spread of this disease, alleviate patients’ suffering, and improve their quality of life. For HCE, liver resection is the preferred radical treatment option. However, HCE often presents with compressive symptoms, and some cases have a prolonged disease course, often accompanied by hepatic insufficiency or even near-failure at the time of diagnosis. Pursuing complete resection blindly may lead to postoperative hepatic failure and poor prognosis. In this case, the cystectomy approach was adopted, and no new onset or implantation metastasis was observed during follow-up, achieving a similarly good radical effect. This provides a new perspective for the treatment of difficult and complex cases of HCE, especially those with poor liver function. Additionally, this case of HCE was complicated by intracystic bile leakage, and postoperative ERCP with biliary stent placement had a good effect in reducing bile leakage. Complete resection of the lesion, if feasible, remains the preferred surgical option. Further exploration of surgical options for difficult and complex cases of HCE is needed in the future. ¹⁵