Primary diaphragmatic hydatid cyst: A rare location of echinococcosis

Hydatid disease most commonly affects the liver and lungs. Primary diaphragmatic involvement is exceptionally rare and often misdiagnosed as hepatic or pulmonary hydatidosis on imaging due to anatomic proximity.

We report a 47-year-old Tunisian woman presenting with intermittent right hypochondrium pain. Laboratory tests and hydatid serology were normal. Computed tomography (CT) imaging revealed a cystic lesion at the dome of the right hemidiaphragm with close contact to the liver, raising suspicion of a hepatic-origin hydatid cyst. Surgical exploration through a right subcostal laparotomy revealed that the cyst arose primarily from the diaphragm, with no hepatic or pulmonary involvement. The cyst was excised completely without rupture. Postoperative recovery was uneventful, and no recurrence occurred during 18 months of follow-up.

Primary diaphragmatic hydatid cysts are rare, representing an unusual localization of Echinococcus granulosus. Preoperative imaging often leads to diagnostic confusion with hepatic dome cysts because precise diaphragmatic origin is difficult to establish. Surgical resection remains the treatment of choice. This case highlights the diagnostic challenges and the importance of intraoperative confirmation.

Primary diaphragmatic hydatid cysts must be considered in endemic areas when cystic lesions arise near the hepatic dome. Accurate diagnosis is difficult preoperatively, and definitive localization is frequently established during surgery.