Distinction of differentiated type early gastric carcinoma with gastric type mucin expression

Intestinal and diffuse gastric carcinomas differ in morphology and growth behavior. Differentiated type gastric carcinoma (DGC), which corresponds roughly with the intestinal type of Lauren, can demonstrate phenotypic properties associated with mucin expression and brush border. However, their clinical significance is controversial. A classification based on mucin phenotype and brush border was performed to determine the clinicopathologic diversity of DGCs in their early stage.

A total of 120 specimens from 116 DGC patients with definite submucosal invasion were evaluated both macroscopically and histologically. All sections were examined immunohistochemically with human gastric mucin, Muc-2, and CD10 and with mucin histochemically with paradoxical concanavalin A staining and high iron Diamine-Alcian Blue. They were classified into gastric type (G-type), intestinal type (I-type), mixed gastric and intestinal type (M-type), or null type (N-type) phenotypes. The immunoreactivity of E-cadherin and beta-catenin also was investigated to determine the correlation between mucin phenotype and clinicopathologic factors.

The G-type phenotype was found to be in contrast to I-type: G-type was an independent factor associated with lymph node metastasis. Significant correlations were observed between the G-type phenotype and the complex type carcinoma found that was histologically: lymphatic invasion, lymph node metastasis, and the abnormal expression of E-cadherin. A significant difference in the proportion of mucin phenotypes between papillary type and tubular type carcinoma was observed. G-type was found to be the predominant phenotype in papillary carcinoma in contrast to tubular carcinoma.

The G-type mucin phenotype and papillary adenocarcinoma should be distinguished from other types of DGCs because of their increased malignant potential in the incipient phase of invasion and metastasis. The significance of G-type and papillary adenocarcinoma should be reflected in the treatment of patients with early stage DGCs, including endoscopic mucosal resection.