Virtual microscopy for histology quality assurance of screen-detected polyps

Aim: Histology quality assurance is crucial for screening programmes and can be performed by circulating glass slides, which has certain intrinsic disadvantages. The present study aimed to assess the accuracy of virtual microscopy in terms of reliability and diagnostic reproducibility in colorectal cancer screening programmes. Methods: 457 consecutive lesions detected in people undergoing colonoscopy were examined histologically in two pathology units, using both traditional optical microscopy and virtual microscopy (6-12 months later). Intra- and inter-observer agreement using the two approaches was determined using κ statistics. Results: Intra- and inter-observer agreements were substantially unmodified by the use of the virtual microscopy approach compared with traditional optical microscopy; moreover, for some histological features critical for patient management in colorectal cancer screening programmes (such as the presence of a villous component within the adenoma), virtual microscopy increased interobserver agreement (κ statistics 0.66 versus 0.52). Conclusions: This study shows that virtual microscopy can be an effective tool for diagnostic quality assurance in colorectal cancer screening programmes, and its accuracy is equivalent to or higher than that of optical microscopy in the validation of histological criteria (eg, advanced adenoma) crucial for patient management in screening programmes.