RESUMEN
Objective To analyze the differences of morphological and microvascular characteristics between hyperplastic polyps and colorectal adenoma (CA) under narrow band imaging (NBI) without magnification endoscopy,and to evaluate the value of NBI in differential diagnosis.Methods Patients with rectal polyps diagnosed by common endoscopy and pathologically confirmed CA and hyperplastic polyps were recruited in this study and under NBI examination.The pit pattern was divided into type A and B according to modified Kudo pit pattern classification.And the vascular pattern was classified into three types,type Ⅰ with invisible microvascular,type Ⅱ with even microvascular arranged along pit and type Ⅲ with uneven microvascular and irregular arranged.The differences of morphological and microvascular characteristics between hyperplastic polyps and CA were compared and the inter-observer consistency of NBI without magnification endoscopy was evaluated.Results Overall,87 patients with 107 polyps (73 CAs,34 hyperplastic polyps) underwent NBI without magnification endoscopy examination.The maximum diameter and the proportion of polyps with sublobe was higher in CA group than that of hyperplastic polyps group (P =0.0023 and 0.0047).In CA group,most pit shapes were type B (86.3％,63/73),and most vascular pattern types were Ⅱ/Ⅲ (82.2％,60/73).The sensitivity,specificity and accuracy of CA diagnosed with features of type B pit shape or Ⅱ/Ⅲ vascular pattern type was 97.3％,82.4％ and 92.5％.The sensitivity,specificity and accuracy of CA diagnosed with combined features of type B pit shape and Ⅱ/Ⅲ vascular pattern type was 71.2％,91.2％ and 77.6％.The mean kappa value of inter-observer consistency was 0.761.Conclusions There are differences in pit shapes and vascular pattern characteristics between CA and hyperplastic polyps.According to these two facts,CA and hyperplastic polyps can be initially differential diagnosed by NBI without magnification endoscopy.