Category: Thyroid

Monitor: 21


Friday, Apr 26
11:30 AM – 12:00 PM

Objective :

The relationship between Graves disease (GD) and thymic hyperplasia (TH) is more than a century old having been first identified by Matti in 1912 and Halsted in 1914. TH can be further classified as true thymic hyperplasia (TTH) or thymic lymphoid hyperplasia (THL) and is usually discovered incidentally during evaluation of other symptoms. The pathogenesis of TH in the setting of GD is unclear, however is hypothesized to be autoimmune mediated or related to hyperthyroidism-induced angiogenesis. In most patients, treatment of GD with antithyroid medications, radioiodine, or thyroidectomy results in involution of thymic hyperplasia.

Methods : N/A

Results : N/A

Discussion :

A 48-year-old female with a history of hypertension and pulmonary embolism (PE) presented to the emergency department (ED) with palpitations, chest pain, lightheadedness and weight loss. On physical exam, the thyroid gland was diffusely enlarged. Her initial laboratory work showed a TSH < 0.001 (0.460-4.7 mIU/L), free T4 2.82 (0.7-1.3 ng/dL), total T3 2.53 (0.58-1.59 ng/mL), free T3 9.44 (2.3-4.2 ng/dL), TSI 293 %, TPO antibodies < 3.0, calcium 12 mg/dL, PTH 17.1 pg/mL (14-72 pg/mL), vitamin D 25-OH 21. During ED evaluation, there was a high suspicion of PE. Subsequent chest CT angiography demonstrated an anterior mediastinal mass measuring 4.0 x 2.5 x 7.1 cm. CT-guided biopsy confirmed thymic hyperplasia with abundant immature T-cells confirmed with flow cytometry. Pertinent tumor markers were negative. The Endocrinology service was consulted for newly diagnosed hyperthyroidism due to GD. Ultrasound of the thyroid showed an enlarged heterogeneous gland with chaotic blood flow. Methimazole therapy was initiated and intravenous fluids were administered for hypercalcemia.

Conclusion :

Thymic hyperplasia is a rare incidental association of Graves Disease. This case illustrates the importance of recognizing this association as in most cases it is a benign condition that can be reversed with correction of GD, thus preventing further unnecessary imaging studies, biopsies and possible surgical treatment.


Losty T. Torres Potter

Endocrinology and metabolism fellow
USF, Florida

Endocrinology and metabolism fellow

Gustavo Meyreles-Chaljub

Endocrinology, Diabetes and Metabolism Fellow
University of South Florida, Florida

USF-Endocrinology and Metabolism Fellow

Natalia Weare-Regales

Endocrinology and metabolism

Endocrinology and metabolism fellow

Pedro Troya

Endocrinology and metabolism attending

Endocrinology and metabolism attending

Madeline Candelario-Cosme

Endocrinology and Metabolism

Endocrinology and Metabolism, USF