Duodenal pseudolesions: the key hole sign

Pseudolesions in the duodenal bulb are produced by barium surrounding and entrapped in contiguous parallel duodenal folds. A typical defect with a "key hole" sign identifies the majority of these pseudolesions allowing for the radiological exclusion of true polypoid masses in the duodenal cap. The filling defects disappear with peristalsis or with distention of the duodenal bulb with air.