Transverse colon herniation through the foramen of Winslow presenting with unusual CT findings.

Bowel herniation through the foramen of Winslow is among the rarest of internal hernias, accounting for less than 0.8%. In its origin, a pivotal role is played by some anatomic variations, or anomalies such as the increased mobility of the right transverse colon, and maybe the exceedingly large bore of the foramen itself. The first case of hernia through the foramen of Winslow was reported by Blandin in 1834. Since then, no more that 200 new cases have been described. Diagnosis usually is established during surgery while treating a bowel obstruction. Only in an exceedingly small group of patients is diagnosis achieved preoperatively on the basis of radiological findings. We describe a preoperatively diagnosed case of transverse colon herniation through the foramen of Winslow, showing a portal vein narrowing and periportal lymphedema at computed tomography (CT). To the best of our knowledge, only a few cases of preoperative CT diagnosis of Winslow foramen hernia have been described in the past. None had the above-mentioned CT findings.