The 2011 International Association for the Study of Lung Cancer (IASLC)/American Thoracic Society/European Respiratory Society guidelines strongly encourage surgical pathologists to minimize the amount of tissue used for diagnosis, in particular by limiting the number of first-line IHC stains.6Thus, this study aimed at evaluating the most useful limited IHC panel including TTF1, Napsin A, p63, and p40 for subclassifying NSCLC. Here, NAPSA is linked to non-small cell lung carcinoma.