The most well‐known is GTF2I, the mutation of which is predominantly observed in type A and AB thymoma.30 HRAS and NRAS are also found at high levels in subtype A and AB, while TP53 is predominantly observed in type C thymoma.31 However, the current known biomarkers for distinguishing thymoma subtypes are not as yet clearly defined. Here, GTF2I is linked to thymoma.