From the case:
Fish mouth (illustration)
{"current_user":null,"step_through_annotations":true,"access":{"can_edit":false,"can_download":true,"can_toggle_annotations":true,"can_feature":false,"can_examine_pipeline_reports":false,"can_pin":false},"extraPropsURL":"/studies/141975/annotated_viewer_json?lang=us"}
In IPMN, dilatation of the main pancreatic duct, with a column of mucin extending into the ampulla of Vater endoscopically, is reminiscent of the open mouth of a fish and is therefore known as the fish mouth ampulla sign.
Case Discussion
Image generated with Midjourney.com by Frank Gaillard.