Morphological Study on Adenoma of the Stomach

Morphological characteristics of gastric adenoma were investigated using 107 lesions (79 cases) of adenoma and 6 lesions (6 cases) of carcinoma in adenoma of the stomachs resected surgically. Gastric adenomas were found in 79 (3.2%) of 2494 stomachs, in 68 (4.6%) of 1472 gastric cancers, and in 52 (7.1%) of 735 gastric cancers of differentiated type, respectively, Gastric adenomas under 2.0cm in the greatest diameter occupied 93.5% of 107 lesions, and in proportion to enlargement in size the number of adenomas decreased. The frequency of IIa-like type, IIb-like type, IIc-like type, IIa+IIc-like type, and IIb+IIa-like type was 64.5%, 16.8%, 6.5%, 11.2%, and 0.9%, respectively. Adenomas with high grade atypia were found in larger lesions (especially more than 2.0cm in size) and in depressed lesions. The incidence of malignant transformation of gastric adenomas was 6(5.3%) of 113 lesions all of them was more than 2.0cm in size, the incidence of malignant transformation by size of adenomas was 0% of 100 lesions under 2.0cm in size and was 46.2% of 13 lesions more than 2.0cm. Two cases of carcinoma in adenoma had notchs on the outline of the lesion just on the border between cancerous part and adenomatous part, which may suggest collision of cancer with adenoma rather than malignant change of adenoma. These findings indicate that gastric adenomas more than 2.0cm in size or dedressed-type adenomas tend to have a cancer focus in them, and that not all carcinoma in adenoma is originated from adenoma, and that the incidence (5.3%) of malignant change reported herein is considerd as a maximum rate