Ectopic thyroid tissue in the anterior mediastinum along with a normally located gland

Ectopic thyroid tissue is a rare developmental abnormality arising from an aberration in the normal migration of the thyroid gland, from the floor of the primitive foregut to its final position. It is usually asymptomatic, often being diagnosed as an incidental finding. However, it can present with symptoms of compression such as chest pain, cough, stridor, dysphagia, dyspnea and superior vena cava syndrome. Herein, we present the case of a 42-year-old male patient, presenting with dyspnea, chest pain and fatigue. Laboratory tests showed low serum levels of thyroid-stimulating hormone (TSH) and a thoracic computed tomography revealed a heterogeneous mass in the anterior mediastinum. The patient underwent a full surgical resection. The postoperative histopathological examination of the mass demonstrated the presence of benign ectopic thyroid tissue with no evidence of malignancy. This case report emphasizes the importance of taking Ectopic thyroid tissue into account when considering the differential diagnosis of a mediastinal mass, as other common diagnoses including lymphomas, dermoid cysts and thymic tumors, require an entirely distinct treatment approach.