Gastric Cancer
Copyright ©2006 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Apr 28, 2006; 12(16): 2510-2516
Published online Apr 28, 2006. doi: 10.3748/wjg.v12.i16.2510
Extremely well-differentiated adenocarcinoma of the stomach: Clinicopathological and immunohistochemical features
Takashi Yao, Takashi Utsunomiya, Masafumi Oya, Kenichi Nishiyama, Masazumi Tsuneyoshi
Takashi Yao, Masazumi Tsuneyoshi, Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
Takashi Utsunomiya, Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
Masafumi Oya, Department of Pathology, Aso-Izuka Hospital, Fukuoka, Japan
Kenichi Nishiyama, Department of Pathology, National Kyushu Cancer Center, Fukuoka, Japan
Author contributions: All authors contributed equally to the work.
Supported by Grants-in-aid for Cancer Research from the Ministry of Education, Science and Culture, Japan and the Fukuoka Cancer Society, Fukuoka, Japan
Correspondence to: Takashi Yao, Department of Anatomic Pathology, Pathological Sciences, Graduate School of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Telephone: +81-92-642-6061 Fax: +81-92-642-5968
Received: August 20, 2005
Revised: November 11, 2005
Accepted: November 18, 2005
Published online: April 28, 2006

AIM: Minimal deviation carcinoma of the uterine cervix, otherwise known as extremely well-differentiated adenocarcinoma (EWDA), is characterized by its benign microscopic appearance in contrast to its aggressive behavior. In order to elucidate the clinicopathological features and biological behavior of the gastric counterpart of EWDA, we, using immunohistochemistry, analyzed nine lesions for the phenotypic expression, proliferative activity, and the expression of oncogene-associated products.

METHODS: Clinicopathological features, including pre-operative biopsy diagnosis, were reviewed. Using immunohitstochemistry, Ki-67 labeling index and expression of p53 and c-erbB-2 protein in the gastric lesions were detected.

RESULT: Locations in the middle or upper third of the stomach and polypoid macroscopic features are characteristic of EWDA of the stomach. Although 4 of the 9 lesions showed only focal lymphatic or venous invasion, lymph node metastasis was not present and none of the patients died of the lesions (mean follow-up period, 56 mo). All 9 cases of EWDA could be classified into gastric phenotype (5 lesions) and intestinal phenotype (4 lesions). The former resembled gastric foveolar epithelium, mucous neck cells or pyloric glands, but their papillary structures were frequently elongated and the tumor cells and their nuclei were slightly larger and more hyperchromatic compared to normal epithelium. The latter resembled intestinal metaplasia with minimal nulcear atypia and irregular glands; two of these lesions demonstrated complete intestinal phenotype, while two demonstrated incomplete intestinal phenotype. Ki-67 labeling index was low and none of the cases revealed over-expression of p53 and c-erbB-2 protein.

CONCLUSION: Unlike minimal deviation carcinoma of the cervix, these findings suggest that EWDA of the stomach is a lesion of low-grade malignancy. This favorable biological behavior is supported by the data of a low Ki-67 labeling index and a lack of p53 or c-erbB-2 protein over-expression. Because of its resemblance to normal gastric mucosa or mucosa with intestinal metaplasia, EWDA is often misdiagnosed. To prevent the misdiagnosis of such lesions, the clinical and pathologic characteristics should be taken into consideration.

Keywords: Stomach neoplasms, Extremely well-differentiated adenocarcinoma, Ki-67, p53, c-erbB-2