Endocytoscopy for the differential diagnosis of colorectal low-grade adenoma: a novel possibility for the “resect and discard” strategy

Abstract Background and Aims Endocytoscopy, a next-generation endoscopic system, facilitates observation at a maximum magnification of ×520. To our knowledge, no study has reported high-precision diagnosis of colorectal low-grade adenoma, endoscopically. We aimed to reveal which endocytoscopic findings may be used as indicators of low-grade adenoma, and to assess whether a “resect and discard” strategy using endocytoscopy is feasible. Methods Lesions diagnosable with endocytoscopy were retrospectively examined between May 2005 and July 2017. A normal pit-like structure in endocytoscopic images was considered a normal pit (NP) sign and used as an indicator of low-grade adenoma. The primary outcome was the diagnostic accuracy of the NP sign for low-grade adenoma. We evaluated agreement rates between endocytoscopy and pathological diagnosis for surveillance colonoscopy interval recommendation (SCIR) and performed a validation study to verify the agreement rates. Results For 748 lesions in 573 cases diagnosed as colorectal adenoma using endocytoscopy, results were as follows: sensitivity of the NP sign for low-grade adenoma: 85.0%; specificity: 90.7%; positive predictive value: 96.6%; negative predictive value: 66.1%; accuracy: 86.4%; and positive likelihood ratio: 9.2 (P Conclusions Endocytoscopy is a very effective modality in determining the differential diagnosis of colorectal low-grade adenoma.