So far, several study showed the potential usefulness of microscopic capillaries, seen by magnifying NBI for predicting gastric neoplasia among superficial depressed or flat elevated early gastric neoplastic lesions [9
]. However, there was no report showing its efficacy in gastric protruding/or polypoid lesions.
In this study, fine mucosal patterns and capillary patterns of the gasric protruding/or polypoid lesions could be classified into four and five categories, respectively. In particular, micro vascular patterns had good correlations with histopathology. Honey comb, and dense vascular patterns showed higher sensitivity and specificity for predicting FGP (sensitivity 94.7%, specificity 97.4%), and HP (sensitivity 93.6%, specificity 91.6%) respectively. FGP is almost always associated with non inflamed normal gastric mucosa, showing hyperplasia of non neoplastic gastric fundic grand [12
], while HP were usually associated with H. pylori
related chronic gastritis, characterized by dilated, tortuous gastric foveoli set within an inflamed, edematous stroma [13
]. Therefore, it may be reasonable to speculate that hyperplasia of normal gastric fundic grand may reflects uniformly arranged honey comb like appearance of the FGP, which is often observed in normal gastric mucosa in the corpus [7
], and the continuous destruction and regeneration of new vessels and edema due to severe inflammation may reflect increased density of irregular vessels in the most of area of the micro structure, seen in HP.
On the other hand, fine net work, core vascular, and unclear patterns presented higher specificity (97%, 100%, and 100%) for predicting GN, and diagnostic efficacy of combined of those micro vascular patterns was favorable (sensitivity 86.2%, specificity 97.0%). Although we could predict the GN from the information of conventional endoscopic findings (anatomical location, Yamada's classification, size, color and the presence of Uneven form or presence of depressed area), it was clear that diagnostic efficacy of micro vascular pattern was better, suggesting that micro vascular patterns by magnifying NBI may grow to be a promising tool for diagnosing gastric protruding/or polypoid lesions. We also examined diagnostic efficacy of combined of both fine mucosal structures and micro vascular patterns, but diagnostic efficacy was not improved compared to micro vascular patterns it self. Our result suggests that, in the gastric protruding/or polypoid lesions, combined of microvascular patterns, rather than fine mucosal patterns are most useful sign for discriminating GN from FGP and FP. Although GN in our study were histologically well differentiated adenocarcinomas or gastric adenomas, and they did not contained undifferentiated carcinoma components (data not shown), in addition to the fine net work pattern, often seen in well differentiated superficial depressed adenocarcinomas [9
], protruding/or polypoid GN showed at least two more suggestive micro vascular patterns: core vascular, and unclear patterns. This is possibly due to feature of gastric protruding/or polypoid lesions. Also, when considering all histological types including FGP and HP, we needed at least five micro vascular patterns to distinguish all lesions. Although our result indicated that five micro vascular patterns had good interobserver concordance in experienced endoscopists, whether our criteria could be well accepted for all of endoscopist, including trainee of magnifying NBI, need to be validated.
In our study, dense vascular pattern, which is a suggestive pattern for HP actually contained four cases of well differentiated adenocarcinomas. Histological examination revealed that the focal components of well differentiated adenocarcinomas in hyperplastic polyps in various degrees, suggesting that this pattern may have possibility of containing small, but considerable percentage of neoplastic components. Although the HP itself are non-neoplastic, dysplastic changes and/or gastric adenocarcinoma may develop within the lesion in rare [14
]. However, the risk of developing an adenocarcinoma within a hyperplastic polyp has been estimated from 0 to 8% (mean 2.1%) and this frequency of occurrence should not be disregard [15
]. As a rule, the endoscopic pictures showing most predominant appearance was used for the assessment in this study, we could not detect the specific micro vascular patterns of well differentiated adenocarcinomas, which might be seen in the tiny area of these lesions. All four lesions that have well differentiated adenocarcinoma components in dense vascular pattern were 5 mm or larger in size (data not shown). Therefore, intensive follow up, polypectomy, or endoscopic mucosal resection may be recommended for such size of gastric protruding/or polypoid lesions with dense vascular patterns.