However, there are only a few reports on NSCLC, which is a special type of lung cancer in which the same tumor cell population diffusely expresses both TTF-1 and p40.[4] This study reported a case of poorly differentiated NSCLC with the diffuse co-expression of TTF-1 and p40 based on second-generation sequencing. The gene discussed is TTF1; the disease is neoplasm.