CLDN18 and adenoma: There are conflicting reports regarding CLDN18 staining within different polyp types: Sentani et al. reported no expression in either hyperplastic polyps (n = 66) or adenomas (n = 57), while 44.4% of sessile serrated adenomas (n = 45) and 12.8% of traditional serrated adenomas (n = 47) exhibited membranous CLDN18 staining [162].