Fig 1. The grade of atypia of gastric tumors according to the World Health Organization (WHO) 2010 classification.

(A) Low-grade intraepithelial neoplasia (HE staining). The tumor ducts consisted of epithelial cells with mild to moderate nuclear atypia. Stratified nuclei and mitotic figures were inconspicuous. (B) High-grade intraepithelial neoplasia (HE staining). The tumor ducts consisted of epithelial cells with high-grade nuclear atypia associated with stratified nuclei and mitotic figures. (C) Intramucosal carcinoma (HE staining). The formation of irregular branching of small ducts and cribriform ducts was evident, with distinct invasion to the stroma of the lamina propria. (D) Intramucosal carcinoma (HE staining). Tumor cells with severe structural atypia show solid and cord-like proliferation, associated with distinct invasion to the stroma of the lamina propria.