Anatomic Pathology / DYSPLASIA IN GASTRIC HYPERPLASTIC POLYPS 224 Am J Clin Pathol 2001;115:224-234 © American Society of Clinical Pathologists p53, But Not c-Ki-ras, Mutation and Down-Regulation of p21WAF1/CIP1 and Cyclin D1 Are Associated With Malignan

To investigate tumorigenesis in the gastric hyperplastic polyp (HP), we evaluated 19 HPs with and 50 HPs without dysplasia (including carcinoma in situ), as compared with normal mucosa and fundic gland polyps. Helicobacter pylori density was highest in HPs without dysplasia. Apoptotic activity and Ki-67 and p53 expression also were higher in dysplasia in HPs than in normal mucosa, fundic gland polyps, or HPs themselves. The p21WAF1/CIP1 and cyclin D1 levels, in contrast, were highest in HPs. In HPs without dysplasia, size was correlated positively with the degree of stromal inflammation and with p53 and cyclin D1 expression. p53 and c-Ki-ras mutations were detected in 41 % (8/19) and 5 % (1/19) of dysplasia (including carcinoma in situ) in HPs. Our results demonstrate tha