Inter-observer variation between general and specialist gastrointestinal pathologists when grading dysplasia in ulcerative colitis

Abstract

Histological dysplasia is the cornerstone of colorectal cancer surveillance in ulcerative colitis (UC). Recently, pathologists have received unfavourable media attention concerning other cancer screening programmes. The aim of this study was to determine whether colonic biopsy specimens should be examined by gastrointestinal pathologists as opposed to generalists, by examining inter-observer variation between the two groups. Fifty-one coded slides showing varying degrees of dysplasia were mailed to seven gastrointestinal and six general histopathologists. Pathologists allocated each biopsy into one of four categories without the benefit of a clinical history or an opportunity to use the 'indefinite' category that is included in the Riddell classification. The responses were analysed using kappa statistics. The overall kappa statistic for gastrointestinal pathologists was 0.30 [95% confidence interval (CI)=0.26-0.34] and for general pathologists 0.28 (95% CI=0.23-0.32). Agreement was best for high-grade dysplasia (kappa of 0.54 and 0.61 for GI and general pathologists, respectively). There was total concordance of the 13 pathologists in only four of the 51 slides (7.8%) (95% CI=0.4-15.2%). It is concluded from these results that gastrointestinal pathologists are no better than generalists when grading dysplasia in UC and that agreement is poor in both groups. There is therefore no evidence that there would be any benefit in having specialist histopathology centres concentrating specifically on the interpretation of all surveillance colonoscopy biopsies from around the UK. It must be made clear to the public that surveillance and screening programmes carry a significant rate of histological error and that perfection cannot be expected or achieved with present methods.

Adherence to surveillance guidelines for dysplasia and colorectal carcinoma in ulcerative and Crohn’s colitis patients in the Netherlands

“…There is still no consensus on management in cases of unifocal or multifocal low grade dysplasia (LGD) in flat mucosa. What complicates the issue, as earlier studies have indicated, is that there seems to be difficulty in confirming dysplasia by the pathologist [7,8] . The management of the different forms of dysplasia varies from no management or intensifying the screening program to immediate colectomy.…”

Relationship between clinical parameters and the colitis-colorectal cancer interval in a cohort of patients with colorectal cancer in inflammatory bowel disease

“…Also the histological evaluation of the biopsies encounters uncertainty. There is a considerable variability in the diagnosis of low or high-grade dysplasia among pathologists (inter-observer variability) and also on a second reading of the same slide by the same pathologist (intra-observer variability) [20,73,74]. The subgroup of patients who develop cancer within eight years disease duration, that is, before guidelines recommend inclusion in surveillance programs might be erroneously excluded from surveillance [75].…”

Ulcerative Colitis and Colorectal Cancer: Aneuploidy and Implications for Improved Screening

“…Instead, epithelial dysplasias have been defined as precursor lesions and are meant to be the most predictive feature of intensive and expensive surveillance programs today (Collins, Feldman, and Fordtran 1987). However, reliable endoscopic sampling and histopathological evaluation is difficult (Eaden et al 2001;Riddell 1998;Lynch et al 1993). Additionally, a review of 12 surveillance studies with 92 detected carcinomas in 1,916 patients revealed that about half of them were advanced Dukes´ C and D malignancies and only 12% were early stage carcinomas (Lynch et al 1993).…”