The thymus is an important immune organ in the human body. It originates from the third (or fourth) branchial arch endoderm during the embryonic period and is a derivative of the primitive foregut epithelial cells. It is attached to the anterior mediastinum as the embryo grows and develops. It has unique clinical and pathological characteristics and is accompanied by a variety of paraneoplastic symptoms. Thymoma is a tumor derived from the thymic epithelium, accounting for about 50% of anterior mediastinal tumors. The clinical manifestations vary and are often accompanied by many autoimmune abnormalities. Recently, the recognition of associated autoimmune intestinal diseases has gradually received attention, but there is no clear report on its incidence.