Histo-clinical classification and follow-up study of gastric polyp.

Gastric polyp was found in 1,616 cases or 0.23% of 711,455 persons through the gastric mass-survey. They were classified into 3 groups: hyperplastic polyp in 61%, gastric polyposa in 34%, and polyp composed of metaplastic epithelium with marked atypism (ATP) in 5%. Gastritis polyposa was subclassified into 5 groups according to its histo-clinical features. Malignant degeneration was suspected in 5 or 2.1% of 236 hyperplastic polyps operated, while no polyp which had changed into cancer was experienced among 974 polyps followed-up by biopsy during the time course of 6 months to 11 years at the longest. On the other hand, coexistence of gastric cancer was found in 13% of cases with ATP. In polyps composed of metaplastic epithelium, there are two kinds of polyp: metaplastic polyp in hyperplastic proliferation and neoplastic polyp. In the follow-up study of 1,104 polyps, the growth of polyp was seen in only 14, and 12 of which were hyperplastic polyp. No change from gastritis polyposa to hyperplastic polyp was observed. The increase in size in 14 polyps was seen mostly 3 to 4 years after they were found and was always transient. From these results, it is considered that most of gastric polyps clinically detected have already completed their growth.