[Isolated retrovesical hydatid cyst. Apropos of two cases].

Isolated retrovesical location of hydatid cyst is a very uncommon condition. Clinical patterns appear after a long course of the cyst. They are represented by hypogastric mass associated with compressive manifestations. Ultrasonography is essential for diagnosis and identification of other sites. When diagnosis is unclear, then CT scan plays a role. Cystectomy and pericystic resection, as extensive as possible, is the adequate treatment that gives successful results in most cases.