A 48-year-old female denied any systemic disease. She denied cigarette smoking and cancer family history. According to the patient, abnormal chest CT scan was found by health examination incidentally on 2022/05/16. At that imaging, an heterogeneous anterior mediastinal tumor about 3.5 cm in greatest dimension was seen. No obvious enlarged lymph node is found. Thymoma was highly suspected. She came to out hospital for tumor resection. Thymic carcinoma, NOS, was diagnosed.