DNA content and mucosal dysplasia in ulcerative colitis. Flow cytometric analysis in patients with dysplastic or indefinite morphologic changes in the colorectal mucosa.

In an unselected population of 108 patients with ulcerative colitis in an ongoing endoscopic cancer surveillance program, high-grade dysplasia was diagnosed in 3, low-grade dysplasia in 11, and mucosal changes indefinite for dysplasia in 11 patients. The abnormal biopsy specimens from these 25 patients and samples from other parts of the large bowel obtained at the same examination were investigated by flow cytometric DNA analysis. One hundred thirty-six of 160 samples (85 percent) gave evaluable DNA histograms and, accordingly, 23 patients were retrospectively investigated. Six patients (26 percent) showed aneuploidy (abnormal DNA stemlines) and 1 had possible aneuploidy. All 3 patients with high-grade dysplasia showed aneuploidy (or possible aneuploidy) preceding or coexisting with the severe dysplastic changes. In 1 of these patients, the presence of aneuploidy preceded two diploid carcinomas. One patient was found to have had aneuploidy for seven years without evident malignant transformation. Further prospective studies are necessary to determine the value of DNA analysis in relation to morphologic examination in surveillance of patients with ulcerative colitis.