When analyzing only poorly differentiated tumors, HMCK was the most sensitive marker for squamous cell lung carcinoma (100%), followed by p63 (97.8%), CK5/6 (87.0%), Sox2 (71.7%), thrombomodulin (58.7%), desmocollin-3 (52.2%), S100A2 (50%), glypican-3 (45.7%), and S100A7 (45.7%). This evidence concerns the gene KRT5 and squamous cell lung carcinoma.