[Histological differential diagnosis of early colorectal carcinoma]

Adenoma was divided into 3 grades of dysplasia, severe, moderate and mild, and histological features of moderate dysplasia were clarified. Severe dysplasia is synonymous with mucosal carcinoma and moderate dysplasia is a borderline lesion between malignant and benign condition. From various investigations such as serial section, electronmicroscopy, immunohistochemistry and DNA analysis, moderate dysplasia was shown to include the earliest stage of carcinoma. Problems of differential diagnosis of dysplasia in ulcerative colitis and its clinical implication were also described. The presence of dysplasia in UC should be used as a marker suggesting a high risk of developing colon cancer in UC patients.