A novel ability of endocytoscopy to diagnose histological grade of differentiation in T1 colorectal carcinomas.

<bold>Background and Study Aims: </bold>Endocytoscopic images closely resemble histopathology. We assessed whether endocytoscopy could be used to determine T1 colorectal cancer histological grade.<bold>Patients and Methods: </bold>Endocytoscopic images of 161 lesions were divided into three types: tubular gland lumens, unclear gland lumens, and fused gland formations on endocytoscopy (FGFE). We retrospectively compared endocytoscopic findings with histological grade in the resected specimen superficial layer, and examined the incidence of risk factors for lymph node metastasis.<bold>Results: </bold>Of the 118 eligible lesions, the sensitivity, specificity, accuracy, negative predictive value, and positive likelihood ratio of tubular or unclear gland lumens to identify well-differentiated adenocarcinomas were 91.0 %, 93.1 %, 91.5 %, 77.1 %, and 13.20, respectively. To identify moderately differentiated adenocarcinomas for FGFE, these values were 93.1 %, 91.0 %, 91.5 %, 97.6 %, and 10.36, respectively. In the 35 lesions with FGFE, the rates of massive invasion, lymphovascular infiltration, and tumor budding were 97.1 %, 60.0 %, and 37.1 %, respectively.<bold>Conclusions: </bold>Endocytoscopy could be used to diagnose T1 colorectal cancer histological grade, and FGFE was a marker for recommending surgery. [ABSTRACT FROM AUTHOR]