Gastric polyp is histologically very diverse and its classification is still unsettled. The purpose of the article is to classify the endoscopically diagnosed polypoid lesions and to evaluate their malignant potential.

A retrospective study was done on 142 cases of endoscopically diagnosed gastric polypoid lesions from September 1993 to May 1996. We investigated their clinical findings, histopathology, and nuclear gradings of PCNA by immunohistochemistry.

1) The mean age is 57.9 and sex ratio os 0.8:1

2) The most prevalent location is antrum(57.7%).

3) Morphologically, Yamada type II is the most frequent(35.9%).

4) Histologically, lesions are classified as true polyps and reactive lesions. True polyps are subclassified as hyperplastic polyp(61.2%), adenomatous polyp(19.4%), mixed adenomatous and hyperplastic polyp(10.2%), fundic gland polyp(2.0%), and adenocarcinoma(7.1%). Reactive lesions are subclassified as chronic superficial gastritis(68.2%), mucosal hyperplasia(15.9%), edema of lamina propria(9.1%), xanthoma(4.5%), and ectopic pancreas(2.3%).

5) Atypical changes is accompanied in 12 cases(20%) of hyperplastic polyps.

6) Adenocarcinoma arising from adenomatous polyp is noted in 6 cases. In hyperplastic polyp one case is combined with adenocarcinoma.

7) Among the true polyps single lesions are 127 cases(89.4%), and multiple lesions, 15 cases(10.6%)

8) Immunohistochemical staining for proliferating cell nuclear antigen(PCNA) reveals that hyperplastic polyps show focal positive rection in the area of pit and fundus, and adenomatous polyps show diffuse positive reaction. Dysplastic foci in both adenomatous and hyperplastic polyps shows diffuse positive reaction of PCNA.

Endoscopically diagnosed polypoid lesions show variable histologic findings ranging from chronic superficial gastritis to adenocarcinoma. They are mainly subclassified as histologically true polyps and reactive lesions. Some of true polyps have atypical changes of varing dgree in not only adenomatous polyps but also hyperplastic polyps.