Small depressed neoplasms of the large bowel: radiographic visualization and clinical significance

Small depressed and flat neoplasms (small flat adenomas) exist in the large bowel and in the stomach. Most have been detected with colonoscopy. We tried to delineate these lesions radiographically. Radiographically, the contour of the lesions measuring 5 mm and less was visualized in 32 (60.4%) of 53 lesions. Radiographic examination preceded colonoscopy in 23 (71.9%) of these lesions. Ten (83.3%) of 12 lesions measuring 6–10 mm were visualized. The central depression was clearly delineated in 32 (60.4%) of 53 lesions measuring 5 mm and less and in 5 of the 12 (41.7%) lesions measuring 6–10 mm. The central depression was not demonstrated in all lesions whose contours were not visualized. The clinical significance of the small depressed neoplasm lies in the fact that a certain number may be a precursor of rapidly growing carcinoma with early submucosal invasion.