Supplementary Material for: Relationship between Immunophenotype and Clinicopathological Findings for Superficial Nonampullary Duodenal Epithelial Tumor

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.