Thymic cysts usually grow slowly, but may grow slightly faster if more predisposing factors are present. Thymic cysts are benign lesions that may be congenital or acquired and usually grow more slowly. However, in some patients, the growth of thymic cysts may be exacerbated by a long history of severe inflammation of the lungs, severe chest trauma, etc. The growth of thymic cysts is more rapid in some patients than in others. However, such rapid growth is rare. Smaller thymic cysts usually have no significant discomfort and should be reviewed regularly. Larger thymic cysts tend to compress the surrounding tissues, resulting in chest pain, difficulty breathing and other symptoms, and require prompt surgical treatment.