First case report of retroperitoneal metastasis of fascioliasis after surgery.

Rationale: Fascioliasis is a rare cause of liver abscesses, and its clinical course consists of hepatic phase and biliary phase.

Patient Concerns: We describe a 58-year-old female patient who presented with a 2-month history of intermittent fever and abdominal pain. An abdominal computed tomography (CT) revealed confluent low-density lesions in the liver. Complete surgical resection of these abscesses was performed, and postoperative pathological examination and serological tests confirmed a diagnosis of fascioliasis. However, 4 months after the surgery, follow-up CT revealed a lesion in the retroperitoneal area. Meanwhile, ultrasonography-guided percutaneous needle biopsy of the retroperitoneal lesion was performed, and a parasitic infection was suspected.

Diagnoses: Retroperitoneal metastasis of hepatic phase fascioliasis.

Interventions: The patient received parasitic resistance treatment with triclabendazole at a dose of 10 mg/kg/d for 2 consecutive days.

Outcomes: After 2 courses of triclabendazole therapy, the retroperitoneal metastasis regressed to a minor lesion.

Lessons: To the best of our knowledge, this is the first case report of retroperitoneal metastasis of fascioliasis, aimed at helping recognize the clinical features and treatment options of this rare disease.