Endoscopic and Histopathological Study about 25 Cases of Minute Superficial Depressed Neoplastic Lesions in the Large Intestine

: We studied 25 cases of minute (less than 5 mm in a diameter) superficial depressed neoplastic lesions during the period of March 1990 to September 1991. These depressed neoplastic lesions were recognized by colonoscopy as asteroid redness with surrounding elevation. The thickness and height of the surrounding elevations were modified by air volume. Occasionally, they seemed according to the air volume to be elevated lesions, though their fundamental form was confirmed as being superficial depressed lesions from observations of histopathological sections and using a dissecting microscope. The endoscopic figures were emphasized by sprinkling them with Methylene Blue. All of the minute depressed neoplastic lesions were histopathologically diagnosed as being tubular adenoma. For the purpose of confirming the histopathological character of the depressed neoplastic lesions (n = 25) and distinguishing them from conventional elevated adenomas (n = 71) of the same diameter, we compared the incidences of glandular crowding, nuclear stratification, nuclear pleomorphism and loss of nuclear polarity in two groups. Glandular crowding and nuclear pleomorphism were recognized significantly more often in the depressed neoplastic lesions than in the elevated adenomas. Although most of the minute depressed neoplastic lesions were fundamentally adenomas, because of their unique histopathologic character, they could give new insight into the development of colon cancer.