Clinicopathological Features of Superficial Non‐Ampullary Duodenal Epithelial Tumors Involving Brunner's Glands

Background and Aims: Although Brunner's glands (BGs), located in the submucosa of the duodenum, may be involved by tumor cells of superficial non-ampullary duodenal epithelial tumors (SNADETs), the detailed incidence and histopathological features have not yet been analyzed. This study aimed to clarify the histopathological relationship between SNADETs and BGs. Methods: We retrospectively analyzed SNADETs that were resected at a single center between 2006 and 2021. Resected specimens were histologically evaluated to determine the presence and/or involvement of SNADET in BGs. The relationship between clinicopathological features and tumor involvement in BGs was also assessed. Results: In total, 114 lesions were included. Direct connection with BGs was seen in 52.6% of SNADETs, and submucosal BG involvement was observed in 7.0% (95% confidence interval 3.1%-13.4%) of SNADETs. The presence of submucosal BG involvement was significantly associated with 0-IIc morphology, high-grade dysplasia or carcinoma, and the gastric mucinous phenotype. The presence of either a lesion size 10 mm or greater or 0-IIc morphology demonstrated a sensitivity of 100%, a specificity of 34.9%, and a false negative rate of 0% for predicting submucosal BG involvement. Moreover, non-neoplastic BGs were exposed at the vertical margin in 15.1% of endoscopic resection specimens. Conclusion: SNADETs can have submucosal involvement via BGs, particularly in lesions fulfilling either a size ≥10 mm or a 0-IIc morphology. These pathological findings suggest that vertical resectability may be relevant in their endoscopic management, although further studies are needed to clarify clinical implications.