KRT5 and lung cancer: Immunohistochemical staining showed positive results for thyroid transcription factor-1 (TTF-1), novel aspartie proteinase A (Napsin A), Cytokeratin 7 (CK7), cytokeratin (AE1/ AE3) and PD-L1 (approximately 50% of tumor cells), as well as negative results for cytokeratin 5/6 (CK5/6) and P40, confirming a diagnosis of right lung adenocarcinoma (T4N2M0, IIIB) according to the eighth edition of the TNM classification of lung cancer (Fig. 1).