Spontaneous exovesiculation of a hepatic hydatid cyst with an intact vesicle: A rare intraoperative finding

Abstract

Background

Hydatid disease remains endemic in many regions, particularly in the Mediterranean basin. While hepatic involvement is common, spontaneous exovesiculation of a hydatid cyst with an intact daughter vesicle is exceptional. This phenomenon results from gradual detachment and extrusion of the germinal layer without rupture or spillage.

Case presentation

A 46-year-old female with a known hepatic hydatid cyst diagnosed two years earlier by abdominal ultrasound (WHO CE2) presented to the emergency department with acute abdominal pain. She had neither undergone surgery nor received albendazole therapy, as she was lost to follow-up after the initial diagnosis. Emergency laparotomy revealed an intact exovesiculated daughter vesicle lying freely in the peritoneal cavity, corresponding to the same cyst previously identified. The vesicle was removed intact without rupture, and the postoperative course was uneventful.

Discussion

Spontaneous exovesiculation of hepatic hydatid cysts represents a rare complication that can clinically mimic cyst rupture or secondary peritoneal hydatidosis. The mechanism is thought to involve progressive thinning of the pericyst and increased intracystic pressure, leading to extrusion of the intact endocyst into the peritoneal cavity. Recognition of this unusual event is crucial to avoid unnecessary extensive resections or contamination during surgery.

Conclusion

Spontaneous exovesiculation with an intact vesicle is a rare but distinctive manifestation of hepatic hydatid disease. Awareness of this presentation and careful surgical handling are essential to ensure complete removal and prevent recurrence.

Highlights

• •Spontaneous exovesiculation of hepatic hydatid cysts is an extremely rare complication.
• •The detached intact vesicle may mimic other intra-abdominal cystic lesions.
• •Intraoperative recognition prevents misdiagnosis and avoids peritoneal contamination.
• •Complete removal without rupture leads to favorable outcomes.

Introduction

Hydatid disease is a zoonotic infection caused by the larval stage of Echinococcus granulosus. It remains endemic in many parts of the world, including North Africa, the Middle East, South America, and Asia. The liver is the most commonly affected organ, accounting for approximately 70 % of cases, followed by the lungs (10–30 %) due to first-pass filtration in the portal and pulmonary circulations [1].

Complications of hepatic hydatid cysts include rupture into the biliary tree, infection, calcification, or secondary peritoneal dissemination. Peritoneal hydatidosis usually results from cyst rupture or spillage during surgery. In contrast, spontaneous exovesiculation, defined as extrusion of the intact endocyst (or daughter vesicle) through the pericystic wall into the peritoneal cavity, is exceptionally rare. Unlike rupture, this event occurs without tearing of the laminated membrane, and thus without leakage of cystic fluid or protoscolices.

We report a unique case of a spontaneous exovesiculation of a hepatic hydatid cyst in a 46-year-old woman, in which the daughter vesicle remained intact within the peritoneal cavity. The case is discussed with emphasis on the possible mechanisms, diagnostic challenges, and surgical management. This report has been prepared in line with the SCARE criteria [2].

Case presentation

A 46-year-old female patient, known to have a hepatic hydatid cyst under follow-up, presented to the emergency department with sudden-onset severe abdominal pain evolving for a few hours. She denied fever, vomiting, or jaundice. Her past medical history was unremarkable, and she had no previous abdominal surgery.

The hydatid cyst had been diagnosed two years earlier during routine abdominal ultrasonography, showing a multivesicular WHO CE2 cyst in segment VI. Surgery was indicated at that time; however, the patient did not attend the scheduled operative management and was subsequently lost to follow-up. She had not received albendazole or any other antiparasitic treatment before the current admission.

On examination, she was afebrile but appeared in pain. Abdominal palpation revealed diffuse tenderness with guarding, suggestive of acute peritonitis. Laboratory tests showed normal white blood cell count and liver function tests. Hydatid serology was not repeated at admission.

Given the acute presentation, an emergency exploratory laparotomy was performed. Intraoperatively, the liver appeared congested but intact, with a partially collapsed hydatid cavity in the right lobe. Adjacent to the liver, an intact translucent vesicle, corresponding to a detached hydatid endocyst, was found lying freely in the peritoneal cavity (Fig. 1). There was no evidence of rupture, contamination, or secondary cysts.

Fig. 1.

Intraoperative finding showing an intact translucent daughter vesicle (endocyst) lying freely in the peritoneal cavity adjacent to the liver, consistent with spontaneous exovesiculation of a hepatic hydatid cyst. The liver surface appears intact with a partially collapsed primary cavity in the right lobe.

The exovesiculated vesicle was carefully removed intact, avoiding any spillage (Fig. 2).

Fig. 2.

Complete removal of the intact exovesiculated hydatid vesicle, demonstrating its smooth, glistening wall and preservation of the laminated membrane. The peritoneal cavity was subsequently irrigated with hypertonic saline to prevent recurrence.

The cystic lesion found intraoperatively corresponded to the same hepatic hydatid cyst previously identified. No secondary hydatid localizations were known or detected. No capitonnage or deroofing of the hepatic cavity was performed; only irrigation with hypertonic saline and drainage were required.

The postoperative course was uneventful. The patient resumed oral intake on postoperative day 2 and was discharged home on postoperative day 4 with a prescription for albendazole 400 mg twice daily for four weeks. At follow-up, she remained asymptomatic with no evidence of recurrence.

Prior CT images could not be retrieved at the time of reporting, although efforts to obtain them from the initial diagnostic workup are ongoing.

Discussion

Hydatid disease remains a significant public health issue in endemic regions due to the close human–animal transmission cycle involving dogs and livestock. The liver is the most frequently involved organ because it serves as the primary filter for Echinococcus embryos after ingestion [1].

Exovesiculation of a hepatic hydatid cyst represents a rare and poorly understood complication. It is distinct from cyst rupture, as the daughter vesicle (endocyst) separates completely from the pericyst and migrates into the peritoneal cavity while maintaining its structural integrity. The pathophysiology likely involves gradual thinning of the pericyst and elevation of intracystic pressure, eventually leading to detachment and extrusion of the vesicle without rupture [3], [4]. Non-compliance with scheduled surgery is a well-recognized issue in endemic regions and may contribute to late complications such as exovesiculation.

Clinically, this process may present as an acute abdomen due to peritoneal irritation or mass effect. Preoperative imaging may reveal a detached cystic structure near the liver, but differentiation from a ruptured cyst or secondary peritoneal hydatidosis is often difficult. Our patient initially presented with a WHO CE2 multivesicular cyst, a type known for higher intracystic pressure, which may predispose to exovesiculation. Ultrasonography and CT typically show a cystic lesion adjacent to a collapsed primary cavity, sometimes described as the “double cyst sign.” [5]. Previous CT images could not be retrieved, limiting preoperative comparison, which is a common challenge in patients lost to follow-up.

Intraoperative findings are diagnostic. The surgeon may observe a smooth, glistening, translucent vesicle separate from the liver surface, as in our case. The main challenges during surgery are to avoid rupture of the intact vesicle, which could cause dissemination or anaphylactic reaction, and to manage the residual hepatic cavity adequately. Peritoneal lavage with scolicidal agents such as hypertonic saline, hydrogen peroxide, or povidone-iodine is recommended to minimize recurrence risk [6].

Albendazole therapy is indicated postoperatively, especially when spillage cannot be excluded or when there is a possibility of microscopic dissemination [7]. The prognosis is generally favorable after complete removal of the cyst and adequate antiparasitic treatment.

Only a few similar cases of spontaneous exovesiculation have been reported in the literature, underscoring the rarity of this event. Awareness of this entity is crucial for both radiologists and surgeons practicing in endemic regions, as it may mimic cyst rupture or other intra-abdominal cystic pathologies.

Conclusion

Spontaneous exovesiculation of a hepatic hydatid cyst is an exceptionally rare event that can mimic rupture. Awareness of this entity is essential for prompt recognition and management. Surgery remains the cornerstone of treatment, with excellent outcomes when performed early.

CRediT authorship contribution statement

Ghazi Lâamiri: Software, Resources, Project administration, Data curation, Conceptualization. Hazem Alouani: Writing – original draft, Investigation, Formal analysis, Data curation, Conceptualization. Houda Gazzah: Writing – original draft, Visualization, Conceptualization. Khadija Yaich: Visualization, Software, Resources. Hassen Touinsi: Writing – review & editing, Validation, Supervision. Mahdi Bouassida: Formal analysis, Data curation, Conceptualization.

Patient consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Source of funding

The study did not receive any grant from funding agencies in the public, commercial or not-for profit sectors.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.