Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) of the lung tumor revealed negative staining for TTF-1 and napsin A mucin, and positive staining for p40 and CK5/6, leading to a diagnosis of non-small cell lung carcinoma (NSCLC) that was not otherwise specified (NOS). The gene discussed is TTF1; the disease is non-small cell lung carcinoma.