Abstract
Thirty nine colonic diminutive early carcinomas (38 carcinomas in situ & 1 invasive carcinoma) out of 6, 390 colonic polyps were identified and removed endoscopically during the past eight years. Thease diminutive carcinomas were studied endoscopically and histopathologically. The results were as follows; 1) The diminutive carcinomas were not so rare among all early ones (10.1%), but not so common in all diminutive polyps (1.1%). 2) Most of them were classified into the protruded type excluding a few lesions showing the flat or depressed type. 3) One third of them could be diagnosed endoscopically by the irregular shape, depression and solid impression suggesting of malignancy. The rest of the lesions were shown later to have carcinomas by the histological examination. 4) 24 cases (63.2%) were accompanied by other neoplastic lesions including focal carcinomas in 10 cases. 5) Histopathology revealed well differentiated adenocarcinoma in all lesions ; "de novo" carcinomas in 15 lesions (38.5%) and carcinomas accompanied with a small amount of adenoma in the rest lesions. In conclusion, both carcinomas accompanied by adenoma and "de novo" carcinomas were proved to exist even in cases of diminutive carcinomas (5 mm or less in diameter). The ratio among them is regarded as 6 : 4.
