KRT5 and neoplasm: Immunohistochemical staining showed that the tumor cells were positive for thyroid transcription factor 1 (TTF-1) and CEA, but negative for prostate-specific antigen (PSA), Wilms tumor 1 (WT-1), p40, cytokeratin 5/6 (CK5/6), CK7, CK20 and anaplastic lymphoma kinase (ALK).