Abstract
Background and study aims The usefulness of endoscopy for diagnosing histological type remains unclear. This
study aimed to examine the diagnostic accuracy of white light endoscopy (WLE), magnified
endoscopy with narrow band imaging (NBI-ME), and NBI-ME with acetic acid enhancement
(NBI-AA) for histological type of gastric cancer.
Patients and methods Patients with depressed-type gastric cancers resected by endoscopic submucosal dissection
were prospectively enrolled, and 221 cases were analyzed. Histological type was diagnosed
by WLE, followed by NBI-ME and NBI-AA. Histological type was classified into differentiated
adenocarcinoma and undifferentiated adenocarcinoma. Histological type was diagnosed
based on lesion color in WLE, surface patterns (pit, villi, and unclear) and vascular
irregularities in NBI-ME, and surface patterns in NBI-AA.
Results Histological types of target areas were differentiated adenocarcinoma and undifferentiated
adenocarcinoma in 206 and 15 cases, respectively. Diagnostic accuracy of WLE, NBI-ME,
and NBI-AA for the histological type was 96.4 % (213/221), 96.8 % (214/221), and 95.5 %
(211/221), respectively. No significant differences were observed among modalities.
Positive predictive value based on endoscopic findings in NBI-ME was 98.0 % (149/152)
for the villi pattern, 100 % (19/19) for the irregular pit pattern, 100 % (9/9) for
the unclear surface pattern with a vascular network, 90.3 % (28/31) for the unclear
surface pattern with mild vascular irregularity, and 88.9 % (8/9) for the unclear
surface pattern with severe vascular irregularity.
Conclusions NBI-ME and NBI-AA did not show any advantages over WLE for diagnostic accuracy. Villi
pattern, irregular pit pattern, and vascular network may be useful for identifying
differentiated adenocarcinoma.
