TTF1 and lung adenocarcinoma: However, in different lung cancer subtypes, TTF-1 positivity changes from 21 to 91%, and galectin-3 shows 49% positivity in the subset of lung adenocarcinomas, and napsin A shows a positivity of less than 5% in thyroid cancers, which means that the IHC results by themselves cannot exclude the rare exceptions [11–13].