Dysplasia and deoxyribonucleic acid aneuploidy in the assessment of precancerous changes in chronic ulcerative colitis. Observer variation and correlations.

Cancer prevention in patients with long-standing ulcerative colitis depends on the detection of epithelial dysplasia in colorectal biopsy specimens. Deoxyribonucleic acid analysis by flow cytometry has also been used to examine biopsy specimens, and might be a more quantitative method of detecting precancerous change. Histology and flow cytometry were used to analyze 333 paraffin blocks from colectomy specimens of 58 patients with extensive ulcerative colitis; 22 of these patients had developed carcinoma. Interobserver agreement between three experienced pathologists grading the sections was good for high-grade dysplasia and no dysplasia, but poor for low-grade and indefinite dysplasia. Deoxyribonucleic acid aneuploidy was easier to recognize than dysplasia and, as with dysplasia, it was found to be associated with patients who had developed carcinomas. The presence of deoxyribonucleic acid aneuploidy correlated with the presence of dysplasia. We believe that dysplasia is a useful marker of premalignant change and that flow cytometry may be useful as a complement to histologic examination when dysplasia is suspected.