[Hyperplasia of the thymus in Graves' disease. A case report].

Graves' disease is rarely associated with hypertrophy of the thymus which takes on a pseudotumor aspect. We observed a case in a 40-year-old woman who presented clinical and biological hyperthyroidism with anti-TSH receptor antibodies, favoring the diagnosis of Graves' disease which was confirmed by scintigraphy. The chest x-ray performed because of chest pain revealed enlargement of the mediastinum. The thoracic CT-scan without contrast injected showed a pseudotumor aspect of the thymus. Medical treatment with anti-thyroid drugs and beta blockers led to regression of the thymus mass. Knowledge of this type of association can avoid unnecessary thymus surgery. The clinical course is favorable irrespective of the type of anti-thyroid drug given.