Review of histological classifications of gastrointestinal epithelial neoplasia: differences in diagnosis of early carcinomas between Japanese and Western pathologists.

Gastrointestinal lesions considered to be high-grade adenoma/dysplasia by Western pathologists using the conventional Western classification are often diagnosed as carcinoma by Japanese pathologists using the Japanese group classification. To overcome these differences, the Padova classification, the Vienna classification, and a revision of the Vienna classification have recently been proposed. The clinical usefulness of these five classifications needs to be reviewed for early gastric, esophageal, and colorectal neoplasias. In 1998, 31 pathologists from 12 countries individually diagnosed the same 35 gastric, 21 esophageal, and 20 colorectal specimens. Their histological diagnoses can be classified conventionally and according to the newly proposed terminology, and from these data, the extent of agreement between pathologists with Western and Japanese viewpoints can be calculated, using kappa statistics. With the conventional Western, Japanese, Padova, Vienna, and revised classifications, the agreement scores were 37%, 37%, 71%, 71%, and 80%, respectively, for gastric lesions; 14%, 14%, 57%, 62%, and 67% for esophageal lesions; and 45%, 50%, 65%, 65%, and 70% for colorectal lesions. The kappa values were lower than 0.3 with the conventional Western and Japanese classifications, but higher than 0.5 for gastric lesions, higher than 0.3 for esophageal lesions, and higher than 0.4 for colorectal lesions with the newly proposed classifications. When the literature regarding treatment indications for early neoplastic lesions is reviewed, it becomes apparent that the categories of the revised classification would fit best with current clinical treatment considerations. This classification would be particularly useful for endoscopically resected specimens, to determine whether additional surgery with lymph node dissection is required. In conclusion, the use of the newly proposed terminology can, in large part, resolve the intercountry differences in the diagnosis of adenoma/dysplasia and early carcinoma. However, the newly proposed classifications should be used with caution for biopsy specimens, as sampling error may result in an underestimation of the neoplastic grade or depth of invasion. For the choice between endoscopic and surgical treatment, assessment of the depth of invasion by endoscopic inspection and ultrasound or radiography is essential.