Primary retroperitoneal hydatid cyst with intraperitoneal rupture: a case report.

BACKGROUND: Hydatid disease is endemic in Mediterranean countries and most commonly occurs in the liver followed by the lung. A primary localization in the retroperitoneum is extremely rare. CASE PRESENTATION: We report the case of a 29-year-old Tunisian patient presenting with progressive left flank pain and skin urticaria. On abdominal ultrasonography and computed tomography scan, a ruptured retroperitoneal hydatid cyst was diagnosed, which was confirmed by positive hydatid serology. The treatment consisted of resection of protruding dome. The evolution was favorable. No local recurrence was detected during postoperative follow-up. CONCLUSIONS: Primary retroperitoneal hydatid cyst is extremely rare and has uncommon presentation, but we should learn the keys to its diagnosis. In endemic regions, high suspicion for this disease is justified regardless of localization.