CTNNB1 and neoplasm: CTNNB1-mutant DF samples consistently displayed nuclear β-catenin expression and were derived from larger-sized tumours compared to samples with wild-type CTNNB1. When we further classified DF cases into 2 subgroups based on the type of specimen, excised specimens with nuclear β-catenin expression frequently displayed CTNNB1 mutation and no statistical correlation between nuclear β-catenin expression and CTNNB1 mutation was observed in biopsies.