Giant ectopic thyroid mass: a case report and review of the literature

Giant mediastinal ectopic thyroid tissue is a rare entity that presents a diagnostic and therapeutic challenge for clinicians investigating mediastinal masses. Most cases are asymptomatic and incidentally detected on imaging. When symptomatic, presentations are typically influenced by the mass's size and anatomical location. In this report, we present a right hemithoracic benign follicular goiter in an asymptomatic patient that was removed through a right posterolateral thoracotomy.

A 39-year-old male is discovered to have an incidental mediastinal mass on a chest radiograph following a road traffic accident. Chest computed tomography (CT) scan revealed a heterogeneously enhancing hyper-vascular mediastinal mass in the right paratracheal location with areas of cystic degeneration and calcification. His thyroid gland was normally located in the neck and was not anatomically a part of the mediastinal mass. A CT-guided biopsy of the mass was positive for thyroglobulin and thyroid transcription factor 1 (TTF-1). The patient's thyroid function tests, including thyroid-stimulating hormone (TSH) and free thyroxine (T4), were within the normal range. During surgery, performed via a right posterolateral thoracotomy, the mass was found to be adherent to lung tissue, posterior mediastinal pleura, right main bronchus, and superior vena cava. A complete surgical excision of the mass was achieved, and the patient underwent an uneventful recovery. The mass was an encapsulated multinodular 15 cm × 12 cm × 9 cm round dark red soft tissue with a firm consistency. Histopathology exhibited thyroid tissue with nodular hyperplasia and cystic changes.

Giant mediastinal ectopic thyroid tissue necessitates surgical excision for both diagnostic and therapeutic reasons. The preoperative assessment of giant mediastinal ectopic thyroid tissue location and size aids in directing the surgical approach for mass excision.