MACROSCOPIC AND HISTOLOGICAL FINDINGS OF FLAT ELEVATION IN THE LARGE INTESTINE

Abstract

We sorted out 51 lesions with flat elevations (28 lesions with adenoma and 23 lesions with early cancer) among 620 adenoma specimens and 113 specimens of early cancer obtained during the past 5-year at our department. All of flat elevations with more than 10mm in diameter were early cancer and in those less than 9mm, incidence of early cancer 26.3%. The distribution of flat type early cancers in the large intestine was similar to that of advanced cancer compared with Is, Ip type early cancers. We devised flat elevations into 5 subtypes according to the macroscopic findings; lesions with a sharp edge and smooth surface (type 1), lesions with a sharp edge and erosion (type 2), lesions with a dull edge and smooth surface (type 3), lesions with a dull edge and central depression (type 4) and lesions with a granular surface (type 5), and studied them histologically. The lesions with a sharp edge, irregular surface and superficial bleeding were frequently carcinomas and superficial bleeding was a common macroscopic findings of sm carcinoma. We suggest that many of the flat early cancers have already invaded into the sub-mucosal layer when grown to 10mm in diameter and morphologically have changed from type 1 lesion to type 2 lesion.