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Background: Molecular features of nonampullary duodenal epithelial tumors (NADETs) remain unclear., Aim: The aim of this study is to determine the association between the genetic features and clinicopathological findings of NADETs., Methods: In total, 75 NADETs were enrolled in this study, and was performed targeted DNA sequencing of the GNAS, KRAS, TP53, and APC genes. Histological grade was classified as category 3 or category 4/5 according to the Vienna classification, and the immunophenotype was categorized as the gastric phenotype (G type), gastrointestinal phenotype (GI type), or the intestinal phenotype (I type)., Results: The prevalence of GNAS and KRAS mutations was significantly higher in the G type than in the GI/I type (GNAS, P = 0.027; KRAS, P = 0.005). In contrast, the frequency of TP53 mutations was significantly higher in the GI/I type than in the G type (P = 0.049). Notably, APC mutations, excluding c.4479 G>A which was synonymous mutation, were more frequently identified in category 4/5 tumors than in category 3 tumors (50% vs. 24.5%; P = 0.039)., Conclusion: G-type NADETs harbored frequent GNAS and KRAS mutations, whereas TP53 mutations are common in NADETs with intestinal features. APC mutations were significantly associated with high-grade neoplasia and invasive carcinoma., (Copyright © 2021. Published by Elsevier Ltd.)

Introduction: The natural history and prognosis of superficial nonampullary duodenal epithelial tumors (SNADETs) remain uncertain. We elucidated the relationship between immunophenotype and clinicopathological features., Materials and Methods: A total of 98 SNADETs were divided into 3 groups according to immunohistochemical findings: gastric phenotype (G type), gastrointestinal phenotype (GI type), and intestinal phenotype (I type). Cellular dysplasia was divided into low-grade dysplasia and high-grade dysplasia/adenocarcinoma (≥HGD). White opaque substance (WOS) deposition was categorized into diffuse WOS, partial WOS, and no WOS, based on endoscopic findings., Results: Of the 98 SNADETs, 4 lesions (4.1%) were G type, 32 lesions (32.7%) were GI type, and 62 lesions (63.2%) were I type. All G-type SNADETs were located in the oral side of the papilla including the bulb, and the rate of bulbar lesions was significantly higher in the G type than in the GI and I types (p = 0.004). The most frequent type of WOS was no WOS (4/4, 100%) for G type, partial WOS (19/32, 59.4%) for GI type, and diffuse WOS (34/62, 54.8%) for I type (p < 0.001), and loss of intestinal character was significantly correlated with WOS deficiency. GI/I-type SNADETs with partial or no WOS and G-type SNADETs were associated with ≥HGD. Additionally, the frequency of ≥HGD lesion was significantly higher in the CD10-negative group than in the CD10-positive group (57.1 vs. 19.8%, p = 0.043)., Conclusion: Pathological intestinal character was correlated with the presence of WOS, and CD10 loss was associated with malignant potential of SNADETs., (© 2021 S. Karger AG, Basel.)

Gastrointestinal stromal tumor (GIST) of the duodenum is rare. Obtaining tissue samples of GIST in the duodenum is difficult, especially when the tumor is located in the distal duodenum. Thus, preoperative pathological diagnosis often becomes difficult. We performed endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) biopsy for two cases with submucosal tumors in the third portion of the duodenum. Tissue samples were successfully obtained and diagnosed as GIST. Partial duodenectomy was performed in the two patients. Thus, we believe that EUS-FNA is a potentially useful diagnostic aid for submucosal tumors in the third portion of the duodenum, and it should be attempted before more invasive approaches.