[Retroperitoneal hydatidosis secondary to hepatic hydatid cyst]

Hydatid disease is a worldwide zoonosis. It is caused by a parasitic platyhelminth of the genus Echinococcus. We present a patient with a fluctuating lumbar tumor in the retroperitoneal space, secondary to a hepatic cyst. the initial diagnosis was made by identification of rostellar hooks from protoscoleces in the fluid aspirated from the abscess. We herein describe the clinical manifestations, diagnosis and medical and surgical treatment of this unusual case and conclude that the development of an accurate diagnosis requires a proper analysis of the patient's epidemiological history, clinical manifestations, imaging studies and laboratory tests. a multidisciplinary approach and differential diagnosis is paramount to be able to establish a cause of the disease to deliver appropriate treatment.