6977 Colonoscopic and pit pattern diagnosis in serrated adenomas of the colon.

Abstract

Background and aims: The histological features of serrated adenomas (SAs) have been proposed (Fenoglio, 1990), and discussed in several reports. However, the characteristic features of these polyps observed by endoscopy are still debatable.We compared the endoscopic features and pit patterns of SAs and hyperplastic polyps (HPs), and attempted to correlate them with histological features. Materials and methods: Endoscopic findings in 74 SAs and 90 HPs were investigated with respect to location and configuration. All of them were endoscopically resected. After fixation and crystal violet staining, the surface pit patterns of these polyps (SAs 52 lesions) were analyzed by dissecting microscopy.We attempted to correlate macroscopic with histologic features, and calculated the incidence of highgrade dysplasia (according to the WHO criteria). Results: SAs were divided into two types according to their endoscopic features; 50 were of the polypoid type (P-type) with a cerebriform or granular surface, and 24 were of the flat type (F-type) with a smooth surface, sometimes showing a granular surface when larger than 10 mm.Thirty-eight (76.0%) of the P-type lesions were reddish and 18 (75.0%) of the F-type were whitish. F-type SAs were similar to HPs in both color and configuration. Although P-type lesions were located predominantly in the proctosigmoid (C, A 12% vs S, R 60%), F-type lesions were distributed almost evenly (C, A 33.3% vs S, R 45.8%). The mean size of P-type lesions was 10.0±5.7 mm and that of Ftype lesions was 8.9±4.5mm, both being significantly larger than HPs (5.4±2.9mm) (P<0.01). With regard to the pit pattern of SAs, tubular, branched or cerebriform pits with edges showing a serrated pattern were seen 34 lesions (P-type 33/35, F-type 13/17). All of HPs showed starshaped pits, or large oval pits with serrated edge. High-grade dysplasia was found in four lesions (4/74; 5.4% P-type 3, S-type 1 ). Conclusion: SAs can be divided into P-type and F-type lesions endoscopically. Although the gross appearanceof F-type lesions resembles that of HPs, it is proposed that pit patterns are useful for distinguishing them.