TTF‐1, which belongs to the NKX2‐1 family, is often expressed in the lung, and its expression in lung adenocarcinoma is considered a specific marker of lung adenocarcinoma.31, 32 As mentioned above, PMA was less likely to harbor EGFR mutations but had a higher frequency rate of KRAS mutations. The gene discussed is NKX2-1; the disease is lung adenocarcinoma.