Specifically, strong staining of SOX9 was observed in 6 of 8 (70%) cases with type A, 3 of 6 (50.00) of cases with type AB, 2 of 9 (22.22%) cases with type B2 thymomas, and 9 of 20 (45%) cases with thymic carcinomas. This evidence concerns the gene SOX9 and thymoma.