The lung puncture biopsy revealed adenocarcinoma, and immunohistological staining results showed positive for cytokeratin 7 (CK7+), cell proliferation antigen Ki-67(50%+), thyroid transcription factor 1 (TTF-1+), Napsin A+, negative for cytokeratin 20 (CK20-), cytokeratin 5/6 (CK5/6-), tumor suppressor gene P40- (Figure 4A). The gene discussed is KRT20; the disease is adenocarcinoma.