Interobserver variability in the diagnosis of ulcerative colitis-associated dysplasia by telepathology

Telepathology (TP) is the practice of remote diagnostic consultation of electronically transmitted, static, digitalized images. The diagnostic efficacy of TP-based consultation services has not been widely tested. Dysplasia that arises in association with chronic ulcerative colitis (CUC) is, at present, the most important marker of an increased risk of malignancy in patients with this disease. Unfortunately, dysplasia is difficult to diagnose histologically and, as a result, suffers from a significant degree of intra- and interobserver variability. Furthermore, it is often necessary to obtain expert consultation of potential CUC-associated dysplasia cases before treatment. Therefore, the aim of this study was to evaluate the utility and interobserver variability of diagnosing dysplasia in CUC with the use of TP. Static, electronically transmitted, digitalized images of 38 CUC cases with areas considered negative, indefinite, or positive for dysplasia (low or high grade) were evaluated independently by four gastrointestinal pathologists. All cases were then graded by each of the pathologists by light-microscopic examination of the hematoxylin and eosin-stained glass slides. The degree of interobserver variability was determined by kappa statistics. Overall, there was a fair degree of agreement (kappa = 0.4) among the four reviewing pathologists after analysis of the digitalized images. The poorest level of agreement was in the indefinite and low-grade dysplasia categories. Grouping together several diagnostic categories (for instance, indefinite and low-grade dysplasia, or low-grade dysplasia and high-grade dysplasia) had no effect on the overall level of agreement. The degree of variability in interpretation of glass slides was slightly better (kappa = 0.43) but still remained fair. After reviewing all cases by glass slide analysis, the diagnosis was changed in 38% of the slides; in the majority of these, the grade of dysplasia was increased. Use of TP for consultation in CUC-associated dysplasia has a moderate level of interobserver agreement. Because of a variety of technical reasons, diagnoses rendered by evaluation of digitalized images tended to be of a lower grade than that observed after a review of the glass slides.