OBJECTIVE: The optimal strategy for the management of definite low grade dysplasia (LGD) detected in surveillance in ulcerative colitis (UC) is unknown, because the natural history of LGD has not been well described. METHODS: We reviewed the Mayo Clinic records of patients with UC found to have flat LGD between 1990 and 1993 in whom a nonoperative strategy was pursued for 2 months or more. RESULTS: Eighteen patients with UC and LGD were observed for a median of 32 months. Nine of 18 patients identified with UC and LGD developed advanced neoplastic lesions during follow-up, which were defined as adenocarcinoma, raised dysplasia, or high grade dysplasia. The cumulative incidence of progression to an advanced lesion was 33% at 5 yr (95% CI = 9-56%). Only one patient developed adenocarcinoma, diagnosed 74 months after his initial finding of LGD and 20 months after his last surveillance exam. Besides this patient, adenocarcinoma was not detected in the colectomy specimens of 13 other patients who underwent surgery. Colectomies were performed for dysplasia or cancer in seven patients, active colitis in five patients, and unknown reasons in two patients. Four patients did not have colectomies. CONCLUSIONS: Neoplastic progression in patients with UC and LGD is common. Total proctocolectomy should be offered to all patients with flat LGD. Our study illustrates numerous pitfalls in the practice of surveillance.
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