Cytokeratin 19 fragment detection has high diagnostic value in non–small cell lung cancer, especially in lung squamous cell carcinoma patients,[15] but its sensitivity is poor.[16] Therefore, this case warns us that when a patient’s chest image is lumpy with high-density shadows, accompanied by elevated serum tumor markers, we should not limit the diagnosis to lung cancer, but also consider the possibility of infectious disease. Here, KRT19 is linked to lung cancer.