Endocrine Abstracts

Background: The association between Graves’ disease and thymic hyperplasia is well documented in the literature. Despite that it remains largely unrecognized in routine clinical practice. The lack of familiarity of usually benign nature of thymic hyperplasia associated with Graves’ disease may result in an aggressive management course, along with associated risks.

Case presentation: A previously healthy 32-year-old female was admitted to hospital with palpitations, intensive sweating, tremor and progressive weight loss in the proceeding two weeks. Laboratory test values were the following: TSH <0.01 mIU/l (reference range 0.55–4.78), FT4–80.9 pmol/l (reference range 11.5–22.7) and FT3–24.5 pmol/l (reference range 3.5–6.5). A thyroid ultrasound was performed and a diffuse thyroid disease was verified. In addition, a sharply bordered mass, which corresponds to the thymus, was determined under the thyroid gland. A CT scan of the chest was conducted and it revealed a solid triangular shape thymic mass in the anterior part of the mediastinum with the largest diameter of 4.6 cm laterolateral, 1.7 cm anteroposterior and 10.7 cm craniocaudal. The volume was calculated to be 43.79 cm². Four months after initial presentation, the patient was biochemically and clinically euthyroid. A repeated CT scan of the chest revealed that the volume of the hyperplastic thymus had reduced to 19.98 cm².

Conclusions: Raising awareness of usually benign thymic hyperplasia associated with Graves’ hyperthyroidism and its resolution with the treatment of the hyperthyroid state should prevent unnecessary thymic evaluation, biopsy and surgery with its corresponding risks and costs.