Thymic nodules and thymomas are not the same concept. Thymic nodules are often described morphologically, and on imaging, lesions <3cm in diameter are generally referred to as nodules, while those >3cm are called masses. Thymoma, on the other hand, is a pathological diagnosis and is the name of a disease. Thymoma can be nodule-like changes or mass-like changes; while thymic nodules may be thymoma, thymic cysts, thymic hyperplasia or incomplete thymic degeneration, or tumors of other tissue origin in the thymic area. So the two are sometimes uniform and sometimes not exactly the same.