Hydatid cyst of the lesser sac with retroperitoneal extension mimicking a pancreatic pseudocyst in a child: a case report

Hydatid disease is a parasitic zoonotic infection caused by Echinococcus granulosus , most commonly affecting the liver and lungs, while retroperitoneal involvement is rare in children. We report the case of a 14-year-old female patient from a rural livestock-raising region who presented with a one-year history of recurrent left-sided abdominal pain, nausea, and postprandial early satiety. Pre-admission abdominal ultrasonography and contrast-enhanced computed tomography demonstrated an 8.1 × 8.6 cm cystic lesion, initially interpreted on radiological reporting as pancreatic psudocyst. Exploratory laparotomy through a left upper transverse abdominal incision revealed a large cystic mass within the lesser sac extending posteriorly down to the pelvic cavity. Diagnostic aspiration yielded clear to slightly yellowish fluid, raising suspicion for hydatid disease. The lesion was treated with 70% ethyl alcohol as a scolicidal agent, followed by partial pericystectomy and evacuation of the cyst contents. The residual cavity was irrigated with povidone-iodine and normal saline, and two drains were placed: one within the cyst cavity and the other in the adjacent residual cavity for external drainage. In the absence of intraoperative cyst rupture, fluid leakage, or spillage of cystic contents, postoperative albendazole therapy was administered at a dose of 10 mg/kg/day for 21 days as adjunctive antihelminthic treatment. At the 6-month follow-up, the patient remained asymptomatic with no evidence of postoperative complications. This case highlights the importance of considering hydatid cyst in the differential diagnosis of upper abdominal cystic masses in children from endemic areas, even when imaging findings are suggestive of other clinical entities such as pancreatic pseudocyst. Clinical trial number: Not applicable.