Mucin phenotype and narrow-band imaging with magnifying endoscopy for differentiated-type mucosal gastric cancer

Background Several studies have described the surface glandular structure in differentiated early gastric cancer observed by narrow-band imaging with magnifying endoscopy (NBI-ME) in two main patterns, i.e., a papillary or granular structure in an intralobular loop pattern (ILL) and a pit structure in a fine network pattern (FNP). However, it is uncertain why the NBI-ME findings of differentiated-type carcinomas are divided into two main patterns. We investigated the significance of the mucin phenotype in the morphogenetic difference between ILL and FNP. Methods We evaluated 120 intramucosal, well- or predominantly well-differentiated tubular adenocarcinomas. In each lesion, one area that showed the predominant pattern of microsurface structures and microvessels was selected and marked by electrocoagulation for a strict comparative study by NBI-ME and pathological investigation. NBI-ME findings were classified into three patterns: ILL, FNP, and intermediate. Mucin phenotypes were judged as gastric, intestinal, or gastrointestinal type by immunohistochemistry. Results The mucin phenotype was gastric or gastrointestinal type in 24 (92.3%) of 26 ILL lesions. Intestinal phenotype was observed in 22 (84.6%) of 26 FNP lesions. The gastrointestinal phenotype was observed in 50 (73.5%) of 68 intermediate pattern lesions. The mucin phenotype and NBI-ME results were significantly correlated ( P < 0.001). Conclusions The mucin phenotype of differentiated early gastric cancer might be involved in morphogenetic differences between the papillary and pit structures visualized by NBI-ME.