Endocrine Abstracts

Introduction

Primary mediastinal goiter is an extremely uncommon entity. The majority of primary mediastinal goiters were reported as incidental findings on chest imaging of asymptomatic patients. Symptoms related to compression of adjacent structures and hyperthyroidism were rarely described. Herein we report a case of subclinical hyperthyroidism secondary to a primary mediastinal goiter.

Observation

A 50 year-old woman was referred to our department for hyperthyroidism. She presented with palpitations and hand tremors for 4 months. No history of dysphagia, dyspnea or hoarseness was reported. Physical examination found homogeneous thyroid gland and no superior vena cava syndrome. Thyroid function tests revealed subclinical hyperthyroidism. Thyroid peroxydase antibodies and thyrotropin receptor antibodies were negative. Thyroid ultrasound showed a normal-sized thyroid gland with a 7.5 mm nodule classified TIRADS II and a voluminous anterior mediastinal mass of 75 mm, hyperechoic, heterogeneous and containing multiple calcifications. Cervico-thoracic CT scan revealed a 120 × 70 × 128 mm anterior mediastinal mass independent from the thyroid gland, containing multiple calcifications, with a large tight contact with the aortic arch, the supra aortic trunks and the superior vena cava. A complete resection of the mediastinal tumor was performed through a total median sternotomy. There were no vascular or tissular connections between the mass and the thyroid gland. The feeding artery was dependent on intrathoracic vessels. The histopathological findings revealed a multinodular colloid hyperplasia with no signs of malignancy. The postoperative outcome was marked by a spontaneous euthyroidism.

Conclusion

Our case highlights necessity to keep in mind that ectopic mediastinal goiter, although uncommon, can induce hyperthyroidism. The final diagnosis of primary mediastinal goiter is made by histopathological examination.