Inverted nonampullary duodenal adenocarcinoma treated with underwater EMR.

Competing Interests: Disclosure All authors disclosed no financial relationships. Commentary A central indentation within a protruding GI lesion is usually associated with malignancy and often indicates a lesion that cannot be successfully removed endoscopically. However, in rare cases, a central indentation can be from inverted growth of a lesion rather than deep invasion. In this case, a protruding duodenal lesion was found in the second portion of the duodenum with central indentation; however, EUS, narrow-band imaging, and CT evaluation suggested the lesion to be intramucosal adenocarcinoma with inverted growth. Underwater EMR was then performed with confirmation of the diagnosis and an R0 curative resection. This case emphasizes the importance of individualizing treatment decisions based on a multimodality work-up. Unusual pathologic changes can present in ways that mimic other pathologic changes, and thorough investigation is critical. Amy Tyberg, MD, FASGE, FACG, Associate Editor for Focal Points