Significance of White Opaque Substance in Superficial Nonampullary Duodenal Epithelial Tumors

White opaque substance (WOS) is an endoscopic finding related to histological grade among superficial nonampullary duodenal epithelial tumors (SNADETs). However, the significance of WOS distribution and chronological changes is unknown.

Images of two different esophagogastroduodenoscopy (EGD) examinations before treatment for SNADETs were evaluated for the chronological change of WOS distribution. WOS distribution was classified into None, Partial, Whole and Marginal according to the degree of WOS. The frequency of chronological change and their relationship to lesion characteristics, including histological grade and epithelial subtypes (intestinal or gastric), were analyzed.

Among 187 lesions, 27 were gastric-types and 160 were intestinal-types, 130 were low-grade adenoma (LGA) and 57 were high-grade adenoma or adenocarcinoma. The median interval between the EGDs was 49 days. Chronological change was more frequently observed in intestinal-types compared with gastric-types (26% vs. 5%, p = 0.01). Gastric-types mostly showed None WOS with no chronological change. Univariate analysis showed that tumor diameter of 10 mm or smaller, intestinal-type, interval between EGD, and LGA were related to chronological change. Multivariate analyses showed that intestinal-type and LGA were significant factors (p < 0.05). The most frequent change was None to Marginal (33%) among intestinal-type lesions with chronological change of WOS distribution.

This study revealed that WOS easily changes among LGA, especially in small intestinal-type lesions. As WOS is a variable finding, diagnosing histologic grade and epithelial subtypes of SNADETs should be based not only on the distribution of WOS, but also on a comprehensive assessment, including white-light endoscopy and image-enhanced endoscopy with magnification.