| [ Summary ] |
We experienced 12,445 early colorectal neoplasms from April 1985 to August 1997, and analyzed them in terms of shape, tumor size, pathological diagnosis and surface structure (so called pit pattern). So we have suggested that depressed lesions (typeIIc, IIc+IIa and IIa+IIc) of early colorectal neoplasm have higher malignant potential than other shape types. On the other hand, type IIa+depression (IIa+dep) is similar in shape to the depressed type of early colorectal neoplasm. Type IIa+dep are smaller than other types (3.50 +/- 1.29mm), however, and are slightly elevated lesion which appears to have a depression. Such a pseudodepression tends to be shallow, ill-defined, and not extensive. Indigocarmine dye spraying seems to be useful in endoscopic observation and differential diagnosis. Type IIa+dep have no malignant potential, 98.7% are tubular adenoma, only 1.3% are intramucosal carcinoma. There is no submucosal invasive carcinoma in this type. On pit pattern analysis, type IIa+dep have mainly the type IIIL pit parrern (97.2%) which is typical of flat, sessile and pedunculated lesions. Type IIIs and V pit patterns which are typical of depressed lesions are recognized in a few lesions of type IIa+dep. We followed up 21 cases of this type for six months or longer and most cases did not change in size and shape. We conclude that type IIa+dep are benign lesions, the begining of flat, sessile and pedunculated lesions. It is very important for endoscopic diagnosis and therapy that endoscopists recognize differences between type IIa+dep and depressed type. |