Endocytoscopic classification of preneoplastic lesions in the colorectum

Purpose The aim of this study is to assess the capability of endocytoscopy (ECS) in differentiating neoplastic from nonneoplastic lesions in the colorectum and to validate an ECS classification. Methods Patients with colorectal polypoid and nonpolypoid lesions ≤10 mm were prospectively included. ECS classification subgrouped nonneoplastic (EC 0) and neoplastic (EC 1–3) lesions. Lesions were observed at super-magnified view (450×) before endoscopic resection. Blinded pathological assessment was obtained. Results Fifty-two lesions were examined in 49 patients (17 polypoid and 35 nonpolypoid). Final pathological diagnosis was normal mucosa or hyperplastic polyp in ten cases, low-grade adenoma in 29, high-grade adenoma in 11, and submucosal invasive cancer in two cases. Positive predictive values of each EC group were 100%, 93.1%, 90.1%, and 100%, respectively. ECS diagnosis correlated completely with pathology in the differentiation between neoplastic and nonneoplastic lesions. Conclusions ECS enabled observation of colorectal lesion at a subcellular level in vivo. The classification of ECS images had a good correlation with the final pathological diagnosis. ECS was useful to differentiate between neoplastic and nonneoplastic lesions.