A case report of hyperthyroid-associated thymic hypertrophy in a child, presenting as an anterior mediastinal mass.

We present the case of an 8-year-old boy with an anterior mediastinal mass and signs of hyperthyroidism. The anterior mediastinal mass had radiologic characteristics suggestive of thymic hypertrophy and regressed with antithyroid therapy. Though thymic hypertrophy is a known manifestation of hyperthyroidism, this is the youngest reported case. In selected cases, the diagnosis may be made based on the clinical picture, radiologic appearance, and response to antithyroid therapy without the need of a thymic biopsy or thymectomy.