Confocal Endomicroscopy in Ulcerative Colitis: Differentiating Dysplasia-Associated Lesional Mass and Adenoma-Like Mass

Background & Aims: The management of dysplasia-associated lesional mass (DALM) and adenoma-like mass (ALM) in chronic ulcerative colitis (CUC) differs radically, involving total pan-proctocolectomy vs endoscopic resection and surveillance. Such lesions cannot be reliably differentiated using conventional colonoscopy. Confocal laser scanning imaging enables in vivo surface and subsurface cellular resolution imaging during ongoing video endoscopy. The aim of this study was to prospectively assess the clinical applicability and predictive power of the Pentax EC3870K endomicroscope for the in vivo differentiation of ALM and DALM in CUC during ongoing videocolonoscopy. Methods: Patients were recruited who had a diagnosis of ALM or DALM within the previous 16 weeks. Confocal laser endomicroscopic (CLE) imaging of the circumscribed lesion and 4 adjacent mucosal segments was performed. Targeted biopsy with and without tissue sampling with endoscopic mucosal resection was performed and compared with conventional histopathology as the gold standard. Results: Thirty-six patients with 36 lesions fulfilled the study entry criteria. Using modified Mainz criteria for the in vivo diagnosis of ALM and DALM, the kappa coefficient of agreement between CLE and histopathologic evaluation was 0.91, and accuracy was 97% (95% confidence interval = 86%-99%). Conclusions: This is the first study addressing the novel application of the Pentax EC3870K endomicroscopy system for the in vivo differentiation of ALM and DALM during ongoing video colonoscopy in CUC. We have shown that ALM and DALM can be differentiated with a high overall accuracy, enabling the safe selection of patients suitable for endoluminal resection versus immediate referral for pan-proctocolectomy.