Isolated mesosigmoidal hydatid cyst as an unusual cause of colonic obstruction: report of a case.

We report herein an unusual case of primary mesosigmoidal hydatid cyst that presented as acute left colonic obstruction mimicking sigmoid colon cancer. A 61-year-old man with a 3-day history of abdominal pain, distention, obstipation, vomiting, and fever was admitted to the emergency department of our hospital. Surgery was performed under a presumptive diagnosis of acute left colonic obstruction. The intraoperative findings were highly suggestive of sigmoid colonic carcinoma and Hartmann's procedure was performed. Histopathological examination of the pathological specimen revealed an isolated hydatid cyst embedded in mesosigmoid which had caused mechanical sigmoidal obstruction. Primary extrahepatic, intra-abdominal localization of a hydatid cyst is not unusual. Therefore, as a hydatid cyst may cause a wide variety of clinical syndromes, it should be kept in mind in the differential diagnosis of mechanical bowel obstruction, especially in endemic regions.