White ring sign is useful for differentiating between fundic gland polyp and gastric adenocarcinoma of fundic gland type

Background: Gastric adenocarcinoma of fundic gland type (GA-FG) is characterized by an elevated lesion with vessel dilation exhibiting branching architectures (DVBA). However, this feature is also found in fundic gland polyp (FGP), posing a challenge in their differentiation. In this study, we aimed to investigate the clinicopathological features of gastric elevated lesions with DVBA and assess the efficacy of the white ring sign (WRS) as a novel marker for distinguishing between FGP and GA-FG. Methods: We analyzed 159 gastric elevated lesions without DVBA and 51 gastric elevated lesions with DVBA, further dividing the latter into 39 in the positive-WRS group and 12 in the negative-WRS group. The clinicopathological features, diagnostic accuracy, and inter-rater reliability were analyzed. Results: Univariate and multivariate analyses for gastric elevated lesions with DVBA identified the histological type consistent with FGP and GA-FG, along with the presence of round pits in the background gastric mucosa, as independent predictors. FGPs were present in 92.3% (36/39) of the positive-WRS group and GA-FGs were observed in 50.0% (6/12) of the negative-WRS group. Positive- and negative-WRS exhibited high diagnostic accuracy, with 100% sensitivity, 80.0% specificity, and 94.1% accuracy for FGP, and 100% sensitivity, 86.7% specificity, and 88.2% accuracy for GA-FG. Kappa values of WRS between experts and nonexperts were 0.891 and 0.841, respectively, indicating excellent agreement. Conclusions: Positive- and negative-WRS demonstrate high diagnostic accuracy and inter-rater reliability for FGP and GA-FG, respectively, suggesting that WRS is a useful novel marker for distinguishing between FGP and GA-FG.