KITLG and thymoma: KITLG was highly expressed in type A and AB thymoma (51 A + AB s 70 B1 + B2 + B3 + C, TCGA‐THYM; P < 0.001; Fig 2a), which was validated in the GEO dataset (11 A + AB vs. 26 B1 + B2 + B3 + C, GSE29695; P < 0.001; Fig 2b).