A "rose is a rose is a rose is a rose," but exactly what is a gastric adenocarcinoma?

In the 14 July 1997, issue of Lancet, Schlemper et al. [1] reported a study in which four Japanese and four Western pathologists (from the United States, Canada, Germany, and Finland) compared their diagnoses of gastric biopsy and resection specimens having epithelial lesions ranging from reactive, through preneoplastic, to invasive carcinoma. These pathologists independently classified microscopic slides from 17 biopsies and 18 mucosal resections of 19 cases of neoplastic and nonneoplastic gastric epithelium. All of the lesions were superficial, involving only the mucosa, or when invasive, not extending beyond the submucosa, thus including examples of early gastric cancer. The selection of primarily superficial lesions focused attention on the minimal criteria required for the diagnosis of malignancy by pathologists from different parts of the world. The pattern that emerged indicated that the terminology favored by the Japanese pathologists differed from that favored by three of the Western pathologists for the same lesions; the fourth Western pathologist sided with the Japanese. Specifically, the Japanese pathologists’ threshold for diagnosing carcinoma was lower than that of the Western pathologists. The Japanese did not require the presence of invasion for a diagnosis of adenocarcinoma of the stomach, whereas the Westerners did. The authors suggest that the different diagnostic approaches brought out in this study reflect underlying differences between Japanese and Western pathologists, assuming that the participating pathologists were representative of Western and Japanese pathologists in general. Clearly, the Western group was not homogeneous, since one member broke ranks and sided with the Japanese. Therefore, we are asked to take it on faith that the opinions and use of terminology of the other three Western pathologists reflect the views of all Western pathologists, whereas the four Japanese pathologists speak for all pathologists in their country. This assumption is tenuous at best; however, for the sake of this discussion, we accept it. Eleven of the 12 cases diagnosed by the Japanese pathologists as definite carcinoma on biopsy were also diagnosed as carcinoma on the subsequent mucosal resection by the same pathologists; the twelfth case was diagnosed as suspected carcinoma on the resection. In contrast, for the same 12 cases, the Western pathologists diagnosed definite carcinoma in only two biopsies, highgrade dysplasia with suspected carcinoma in four biopsies, high-grade dysplasia alone in three biopsies, and low-grade dysplasia in three biopsies. Definite carcinoma was diagnosed in only three of the subsequent resections, all of which were designated as either suspected or definite carcinoma on biopsy. Thus the Japanese and Western pathologists were consistent in the application of their own criteria to both biopsies and resection specimens, and the differences in diagnoses are truly the result of differences in diagnostic criteria and are not related to sample size. Two other cases diagnosed as low-grade dysplasia on biopsy and resection by the Westerners were both diagnosed as definite carcinoma on biopsy and definite carcinoma and suspected carcinoma on resection by the Japanese, again indicating consistency among members of the two groups. However, in two additional cases that were called low-grade dysplasia by the Western pathologists, high-grade dysplasia and definite carcinoma were diagnosed by these same pathologists in the resection specimens, suggesting that Western low-grade dysplasia may be more ominous than previously suspected. The Japanese called these same two lesions definite carcinoma and adenoma with severe atypia on biopsy and