Evaluating the usefulness of considering the size and morphological type of type B2 vessel area based on Japan Esophageal Society classification in estimating tumor invasion depth in superficial esophageal squamous cell carcinomas: study protocol for a prospective observational study (Japan BEES study)

Table 1 Japan Esophageal Society magnifying endoscopic classification and corresponding depth of invasion

Type of vessels	Definitions	Tumor invasion depth
Type A	Normal intrapapillary capillary loops or abnormal microvessels without severe irregularity	Non-cancerous
Type B	Abnormal microvessels with severe irregularity or highly dilated abnormal vessels
B1	Type B vessels with a loop-like formation	EP/LPM
B2	Type B vessels without a loop-like formation	MM/SM1
B3	Highly dilated Type B vessels whose calibers appear to be more than thrice that of usual B2 vessels	SM2-3

MM Muscularis mucosa, SM1 Upper third of the submucosal layer, EP/LPM Epithelial/lamina propria

ISSN: 1471-230X