Outcome of "indefinite for dysplasia" in inflammatory bowel disease: correlation with DNA flow cytometry and other risk factors of colorectal cancer.

Dysplasia that develops in the setting of inflammatory bowel disease precedes colorectal cancer (CRC). The category of "indefinite for dysplasia (IND)" is used often in equivocal cases, but its clinical significance remains unclear. Flow cytometric analysis of DNA content (aneuploidy) has shown some promise in stratifying patients into low or high risk of CRC, but there are few reports that have specifically evaluated the outcome of IND. As such, we analyzed a series of 84 IND inflammatory bowel disease patients seen at the University of Washington and Harborview Medical Centers from 2003 to 2013 to determine the outcome of IND. Hospital electronic medical records were further reviewed to correlate outcome with the type of lesion (flat versus polypoid), primary sclerosing cholangitis, active inflammation in the area of IND, and DNA flow cytometric data. The data show that 13% of IND cases were found to have low-grade dysplasia, whereas only 2% of IND cases showed advanced neoplasia (high-grade dysplasia or CRC) after a mean follow-up of 28 months. The risk of neoplasia was not significantly associated with the type of lesion (P = .94 from log-rank test), primary sclerosing cholangitis (P = .94), or active inflammation (P = .41) in this cohort. However, the finding of DNA aneuploidy at baseline IND was predictive of subsequent detection of neoplasia (P = .037). IND patients with abnormal DNA flow cytometric results may warrant more careful follow-up, but conversely, IND in the setting of normal DNA content may require less frequent surveillance colonoscopy.