Clin Endosc.  2021 Jul;54(4):570-577. 10.5946/ce.2020.205.

White Opaque Substance, a New Optical Marker on Magnifying Endoscopy: Usefulness in Diagnosing Colorectal Epithelial Neoplasms

• Yamasaki K
• Hisabe T
• Yao K
• Ishihara H
• Imamura K
• Yasaka T
• Tanabe H
• Iwashita A
• Ueki T

• KMID: 2518861
• DOI: http://doi.org/10.5946/ce.2020.205

Abstract

Background/Aims
A white substance that is opaque to endoscopic light is sometimes observed in the epithelium during narrowband imaging with magnifying endoscopy of gastric or colorectal epithelial neoplasms. This prospective observational study aimed to determine whether the morphology of the white opaque substance (WOS) allows differential diagnosis between colorectal adenoma and carcinoma.
Methods
A consecutive series of patients with colorectal adenomas or early carcinomas who underwent endoscopic resection or surgical excision were studied. The morphology of the WOS was determined based on endoscopic images before the histopathological diagnosis was performed. The primary outcome was the diagnostic performance of an irregular WOS as a marker of colorectal carcinoma.
Results
The study analyzed 125 lesions. A total of 33 lesions showed an irregular WOS, and 92 lesions showed a regular WOS. Among the 33 lesions found to show an irregular WOS, 30 were carcinomas. Among the 92 lesions showing a regular WOS, 79 were adenomas. With irregular WOS as a marker of carcinoma, the diagnostic accuracy was 87%, sensitivity was 91%, and specificity was 86%.
Conclusions
This study demonstrated the potential usefulness of the morphology of the WOS as a marker for the differential diagnosis between adenoma and carcinoma in cases of colorectal epithelial neoplasms.

Keyword

Colorectal neoplasms; Magnifying endoscopy; Narrow band imaging; White opaque substance

Figure

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  Fig. 1. Endoscopic findings of white opaque substance (WOS)-positive and WOS-negative colorectal epithelial neoplasms. (A) Image of a WOS-negative colorectal epithelial neoplasm observed with white light. (B) Magnifying narrow-band imaging (NBI) endoscopic view of the square area. The WOS is absent, with the microvessels clearly visible. (C) Image of a WOS-positive colorectal epithelial neoplasm observed with white light. (D) Magnifying NBI endoscopic view of the square area. The WOS is present, with the microvessels practically obscured.

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  Fig. 2. Determination of whether a lesion is white opaque substance (WOS)-positive. (A) The morphology of the WOS can be visualized. The WOS is present in no less than half of the area when visualized under maximal magnification. (B) The morphology of the WOS cannot be evaluated. Although the WOS is seen in the areas identified by red arrows when visualized under maximal magnification, it is present in less than half of the overall area.

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  Fig. 3. Morphological findings of the white opaque substance (WOS). (A) Regular WOS: morphology of the WOS shows a well-organized and symmetrical distribution of a regular reticular pattern. (B) Irregular WOS: morphology of the WOS shows a disorganized and asymmetrical distribution of an irregular speckled pattern.

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  Fig. 4. Participant flow. HP, hyperplastic polyp; SSA/P, sessile serrated adenoma/polyp; WOS, white opaque substance.

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