肝臓の巨大水胞症における未破裂小胞の自発的胞外排出：まれな術中発見

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.

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.

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.

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.