TTF1 and lung adenocarcinoma: Lung CT-guided puncture biopsy, immunohistochemistry ALK (D5F3) (−), CD56 (−), CDX2 (−), CK20 (−), CK5/6 (−), CK7 (+), EGFR (+), Ki67 (hot zone + 40%), P40 (−), TTF-1 (+), Villin (−), combined with immunohistochemistry, led to the diagnosis of adenocarcinoma of the lung (Fig. 1a).