Giant primary hydatid cyst of the sigmoid mesocolon: a surgical case report.

Giant primary hydatid cysts of the sigmoid mesocolon are exceptionally rare, and their exact site of origin may be difficult to establish before surgery. We report a 51-year-old woman with an 8-year history of progressive abdominal distension and vague abdominal discomfort. CT showed a multilocular cystic lesion of size 30 × 22 × 28 cm extending from the pelvis to the upper abdomen, with internal septations and multiple daughter cysts. Echinococcus serology was positive, with no radiological evidence of hepatic or pulmonary hydatid disease. The patient had received several previous courses of albendazole without sustained improvement, although the duration and adherence of these courses could not be independently verified. At laparotomy, the cyst was found to arise from the sigmoid mesocolon and was excised by total pericystectomy, with preservation of the sigmoid colon and mesocolic vessels. Recovery was uneventful. Albendazole was continued postoperatively for three months, and no recurrence was seen on clinical and ultrasonographic follow-up at 6 months. This case illustrates a rare giant primary sigmoid mesocolon hydatid cyst in which the diagnosis was suspected radiologically, but the precise mesocolic origin was confirmed only intraoperatively.