TTF1 and lung adenocarcinoma: The metastatic adenocarcinomas showed the almost same morphological and immunohistochemical findings as the lung adenocarcinomas: that is, they were positive for CK7 and negative for CK20, TTF-1 and Napsin A. Although the frequency of such primary lung adenocarcinomas is low [4], no adenocarcinoma was detected in other organs.