Previous studies in Asian samples have shown that MLH1, MGMT, CDKN2A, and RASSF1A genes are hypomethylated in thymomas as compared with thymic carcinomas or neuroendocrine tumors (Hirabayashi et al., 1997; Suzuki et al., 2005; Chen et al., 2009; Mokhtar et al., 2014; Kajiura et al., 2017). This evidence concerns the gene MLH1 and thymoma.