Inflammatory omental cyst adjacent to the transverse colon mimicking appendicitis in an adult patient.

Cysts of the omentum are rare and most frequently discovered in children. These cysts may cause abdominal distension, pain, or vomiting. Omental cysts with right lower quadrant pain are found even more rarely in adults. We describe a 44-year-old male who had a 2-day history of abdominal pain localized in the right lower quadrant. Before surgery, acute appendicitis with intra-abdominal abscess was suspected, but during the operation, an infected cyst of the omentum, adjacent and adherent to the redundant transverse colon, was found to have been causing these symptoms. Despite the fact that cysts of the omentum have been reported rarely, the operator should be aware that the cyst is a benign entity and the surgical strategy should be different from that for malignancy. We should keep the possibility of omental cyst in mind to avoid unnecessary bowel resection and potentially harmful inappropriate treatment.