Endoscopic features of submucosal invasive non-ampullary duodenal carcinomas.

Background and Aim It is imperative to distinguish superficial non-ampullary duodenal carcinomas (NADCs) between intramucosal and submucosal invasive carcinoma for treatment selection. The aim of this study was to evaluate the clinicopathological differences of intramucosal and submucosal carcinoma. Methods This was a retrospective, single-center study comprising 134 patients with 137 superficial NADCs during May 2005 and March 2018. Clinicopathological characteristics and treatment outcomes data were used to perform a comparative analysis of endoscopic findings, preoperative diagnoses of depth of cancer, and treatment outcomes of histologically diagnosed intramucosal and submucosal carcinoma. Results Of the 137 NADCs, 125 (91%) were intramucosal, and 12 (9%) were submucosal. The proportion of submucosal carcinoma was significantly higher on the oral side of the papilla than on the anal side (16% vs 1%, P = 0.002). Submucosal tumor-like appearance was more frequent in submucosal than in intramucosal carcinoma (58% vs 13%, P = 0.001). There was no significant difference in tumor diameter between the groups, but 33% of submucosal carcinomas were <= 10 mm. Correct preoperative diagnosis of depth was achieved in 33% of submucosal carcinoma. Submucosal carcinoma was frequently underestimated when tumor diameters were <= 10 mm. Conversely, intramucosal carcinoma was frequently overestimated when the tumor was >= 30 mm and had thickness or giant nodules. Lymph node metastasis was found in one submucosal carcinoma patient. Conclusions The possibility of submucosal invasion should be considered when NADCs are located on the oral side of the papilla or have submucosal tumor-like appearance even if tumor diameters are <= 10 mm.