A 23‐year‐old Chinese woman with a 5‐year history of Graves’ disease (GD) was admitted for a newly diagnosed ovarian tumor. During workup for the tumor, computed tomography (CT) of the chest incidentally showed a large homogeneous anterior mediastinal opacity, 8.6 x 3.1 x 7.4 cm. Physical examination revealed a diffusely enlarged thyroid. Thyroid stimulating immunoglobulins were elevated at 468%, TSH < 0.03 mU/mL, free T4 3.1 ng/dL. Mediastinal biopsy showed immature T cells, negative for primary malignancy or metastases. She was started on treatment with methimazole for hyperthyroidism, underwent salpingo‐oophorectomy and was discharged with adjuvant chemotherapy for stage Ic ovarian papillary cystadenocarcinoma. Her free T4 returned to normal within 2 months after optimization of methimazole treatment. Chest CT showed that the mediastinal mass had decreased to 2.4 x 1.2 x 2.3 cm at that time. However, despite maintenance of her euthyroid status, repeat CT 6 months after treatment revealed that the homogeneous mediastinal mass had increased to 5.2 x 3.1 x 7.2 cm. The patient was referred to cardiothoracic surgery for consideration of thymectomy secondary to failure of regression of the mass with medical management of her hyperthyroidism.
Thymic hyperplasia in patients with Graves’ Disease (GD) was first reported by Halsted in 1914. It has been reported that immunoglobulins from a patient with Graves’ disease stimulated thymocyte mitogenesis in vitro and thymic tissue showed expression of thyroid stimulation hormone (TSH) receptor gene, thereby suggesting local production of TSH receptor. Although a study demonstrated approximately 38% of patients with thyrotoxicosis have histologic changes in the thymus gland, these findings are usually minimal. Radiologically detectable thymic enlargement as an anterior mediastinal mass has been infrequently reported. Several cases describe that these anterior mediastinal mass often represent benign thymic hyperplasia and regress within a few months after treatment of hyperthyroidism. However, unnecessary surgical interventions have been performed in half of these cases due to a small, yet true concern for neoplasms such as thymoma. A recent review recommends surgical intervention if the size of the mass does not decrease in spite of the patient being euthyroid for several months however little is known about the optimal timing of surgical intervention. In our case, the size of the anterior mediastinal mass significantly increased in a 6‐month follow‐up despite maintenance of the euthyroid status and thus she was referred to surgery.
The literature on the management of patients with GD presenting with a mediastinal mass is limited and the true risk of mediastinal neoplasms remains unknown. Our case suggests the importance of further accumulation of long‐term follow up data on patients who present with mediastinal mass with GD to better understand the clinical course and the optimal timing of surgical intervention.
To cite this abstract:Ueno R, Sasaki K, Nagasaka M. A Case of Persistent Anterior Mediastinal Mass in a Patient with Graves’ Disease. Abstract published at Hospital Medicine 2014, March 24-27, Las Vegas, Nev. Abstract 659. Journal of Hospital Medicine. 2014; 9 (suppl 2). https://www.shmabstracts.com/abstract/a-case-of-persistent-anterior-mediastinal-mass-in-a-patient-with-graves-disease/. Accessed January 17, 2020.