TTF1 and lung adenocarcinoma: In contrast, TTF-1−/napsin A + , TTF-1 + /napsin A−, and TTF-1−/napsin A− were seen in 8.3%, 3.3%, and 9.2% of lung primary adenocarcinomas, respectively [30]. These results indicate that a few groups of lung adenocarcinomas may show “TTF-1 + /napsin A−” pattern in immunohistochemical staining.