Hyperplasia of the thymic gland in a patient with Graves' disease.

A tumor-like lesion in the anterior mediastinum was recognized in a 21-year-old female patient with Graves' disease. A CT examination and MRI suggested a thymoma. A subtotal thyroidectomy and a total thymectomy were therefore performed simultaneously. A pathological study of the thymic mass showed thymic hyperplasia. These findings suggest that an enlarged anterior mediastinal mass in a Graves' disease could thus sometimes turn out to be thymic hyperplasia and not a thymoma.