Thymoma
（重定向自Thymus neoplasms）
![](/Images/godic/202502/16/Encapsulated_thymoma4117.jpg")
![CT scan of the chest revealing a large necrotic mass in the left anterior mediastinum (indicated by the red line). Histology later established the diagnosis of a thymoma.](/Images/godic/202502/16/Anterior_mediastinal_mass_thymoma_diagram4117.jpg")
![Another axial slice of a CT scan of the chest showing a small thymoma anterior to the heart (marked with the red line).](/Images/godic/202502/16/Tumor_Thymoma14117.JPG")
Thymoma is a tumor originating from the epithelial cells of the thymus. Thymoma is an uncommon tumor, best known for its association with the neuromuscular disorder myasthenia gravis; thymoma is found in 20% of patients with myasthenia gravis. Once diagnosed, thymomas may be removed surgically. In the rare case of a malignant tumor, chemotherapy may be used.