Diagnostic value of DNA image cytometry in ulcerative colitis

The increased risk of colorectal cancer in patients with extensive, long-st anding ulcerative colitis is well established. The interpretation of dyspla sia as the common precursor lesion of colorectal cancer in ulcerative colit is is, however, subject to inter- and intraobserver variation. The histolog ic diagnosis is particularly difficult in the presence of acute inflammatio n. Therefore, the analysis of ploidy patterns might be a more objective dia gnostic tool. In the present study, the correlation of ploidy and dysplasia of the colonic mucosa was evaluated in the absence and presence of inflamm ation. Image cytometry was performed on 561 fixed, paraffin-embedded tissue specimens from 67 patients with ulcerative colitis. Twenty patients had lo ng-standing and extensive disease, including eight patients in whom the col itis was associated with colorectal cancer. Dysplasia was only found in pat ients with long-standing colitis or with colorectal cancer and was signific antly more often diagnosed in the case of concomitant inflammation. On the other hand, aneuploid patterns were shown to occur independent of inflammat ory activity. Aneuploidy was present in all colorectal carcinomas associate d with ulcerative colitis and in 46.2% of specimens with dysplasia. Moreove r, aneuploidy was detectable in four of 12 samples with low-grade dysplasia as well as in one case devoid of any dysplastic alteration. Ulcerative col itis patients with low-grade dysplasia plus aneuploidy probably represent a subgroup that might be at higher risk of developing colorectal cancer than patients with low-grade dysplasia alone. All in all, image cytometry analy sis might be instrumental in identifying neoplastic lesions even in cases o f increased inflammatory activity or regenerative change.