Echinococcosis is a parasitic disease that is produced by Echinococcus granulosus and still represents an important medical problem in many countries. Echinococcosis in extrahepatic sites is usually asymptomatic unless the cyst causes symptoms due to pressure, as in our case, or ruptures to the peritoneal cavity. Echinococcal cysts at unusual locations many times pose diagnostic dilemmas, and the diagnosis sometimes is made intraoperatively. Primary ovarian and paraovarian cyst hydatid disease is a very rare entity. In our case, a 25-year-old female gravida 1, para 1, was admitted to the emergency department of the Alzahra Hospital of Tabriz due to diffuse abdominal pain, nausea, abdominal distension and urinary frequency of ten-day duration and exacerbation of pain from a few hours before admission. Clinical examination revealed tachycardia of 105 per minute, normal body temperature and normal blood pressure. Abdominopelvic sonography revealed a mass with regular thick contour located in the left ovary suggestive of huge cystadenoma or carcinoma of the ovary.

Emergent laparotomy was performed for suspected adnexal torsion. Intra operative findings were a large paraovarian mass with thick wall without any torsion. Mass was removed completely and sent for frozen section study. Pathological examination showed the diagnosis of hydatid cyst.

The postoperative period was uneventful and the patient was discharged 3 days later, with the advice to receive Albendazole. The patient referred to a general surgeon for management of the hepatic cysts.