Based on the 2021 WHO classification of thoracic tumors [39], we divided HNF4α-positive adenocarcinoma cases (n = 33) into two groups: the variant group (mucinous, enteric, and colloid adenocarcinomas) (n = 18) and the conventional non-mucinous group (acinar, papillary, and solid adenocarcinomas) (n = 15) (Fig. 2a). Here, HNF4A is linked to adenocarcinoma.