Duplication of transverse colon: report of one case.

Alimentary tract duplications are very rare, with a reported incidence of 1 in 5000 live births. However, it rarely affects the transverse colon. We reported a case of duplication of the transverse colon in a 12-year-old boy with an unusual presentation mimicking megacolon. Barium enema revealed a large sac with massive fecal material retention in the left side of abdomen. Barium filling of the sac displacing bowel loops was noted on the post-evacuation film. He received a segmental resection of the transverse colon including the duplicated colon and end-to-end colo-colostomy. Pathology revealed whole muscle layer of colon compatible with duplication. No other associated anomaly was noted in this case. The case demonstrates three relatively uncommon presentations, including transverse colon location, late manifestation and dilated colon mimicking megacolon radiologically. It also emphasizes that barium enema with post-evacuation film aids in the preoperative diagnosis of duplication.