Through a combination of single-cell/single-nucleus RNA-Seq (sc/snRNA-Seq) data analysis, immunohistochemistry, and primary macrophage studies, we have identified pathogenic macrophages characterized by Tet methylcytosine dioxygenase 3 (TET3) overexpression (Toe-Macs) in 3 major human diseases associated with chronic inflammation: metabolic dysfunction–associated steatohepatitis (MASH), non–small cell lung cancer (NSCLC), and endometriosis. This evidence concerns the gene TET3 and lung cancer.