Retrovesical and retroperitoneal extrarenal hydatid cyst: descriptive study of 9 cases.

Objective: To determine the clinical, radiological and surgical features of retrovesical, retroperitoneal hydatid cyst and to discuss the aetiology an d pathogenesis. Material and Methods: Nine cases of hydatid cyst operated in the urology de partment of Charles Nicolle hospital in Tunis between 1982 and 1998 were re viewed: five retroperitoneal sites and 4 retrovesical sites. Results: Retrovesical and retroperitoneal sites represent about 10% of all operations for hydatid cyst in our department. The mean age of our patients was 49.8 years. The clinical presentation was dominated by voiding disorde rs in the cases of retrovesical hydatid cyst (4 cases) and the appearance o f a lumbar or abdominal mass with or without associated abdominal pain in t he cases of retroperitoneal hydatid cyst (5 cases). The positive diagnosis was based on abdominopelvic ultrasonography, completed by computed tomograp hy in 3 patients. All patients were treated by wide cyst resection with a f avourable course and no recurrence. Conclusion: Retrovesical and retroperitoneal hydatid cysts are rare, but no t exceptional in a country with a high endemic rate, such as Tunisia. The d iagnosis can be confirmed by radiological investigations. Implantation of t he hydatid larva is essentially haematogenous. However secondary implantati on in the pouch of Douglas of protoscolex derived from rupture of an intrap eritoneal cyst can also be responsible for some retrovesical sites.