The position of EUS in the diagnosis of duodenal tumors

[Background] The majority of duodenal cancers are clinically M, however, there are some lesions with thick or submucosal tumor (SMT)-like morphology which are suggestive of SM invasion. Although endoscopic ultrasound (EUS) is a modality that can visualize subepithelial structure, its position in the diagnosis of duodenal tumors and ability to predict the difficulties in treatment are still unclear.
[Method] From April 2020 to February 2021, EUS was performed on duodenal tumors with thick, depressed, SMT-like morphology or recurrent lesions. And their EUS images and histological findings were compared.
[Result] Among the endoscopically diagnosed 200 non-papillary duodenal tumors, 38 lesions presented with thick, depressed, or SMT-like morphology. Epithelial tumors and Brunner's gland-related lesions were suspected in 30 lesions, and finally, histological analysis was available in 23 lesions. Of the 9 lesions with thick morphology that were judged to be tumors on Brunner's gland, 7 were adenomas or carcinomas, and all the lesions had proliferation of Brunner's gland below the tumor. Two lesions had tumor echoes extending into the deep submucosa, and both of them were invasive carcinoma (including T2). Six recurrent, high elevation or depression lesions showed preserved submucosa and were successfully treated by endoscopic resection.
[Conclusion] In duodenal tumors, lesions with thick, depressed, or SMT-like morphology are not necessarily suggestive of SM carcinoma. And EUS may play adjunctive a role in determining the treatment strategy of those duodenal tumors.