[Ectopic thyroid tissue: an unusual differential diagnosis of space-occupying mediastinal lesions]

The differential diagnosis of soft tissue masses of the anterior mediastinum includes cervical goiter extending into the mediastinum, germ-cell tumors, masses originating from the thymus, lymphoma and sternal tumors. A rare cause is ectopic mediastinal goiter without a link to the cervical thyroid. We report the case of a 36-year-old female patient with accidental chest X-ray finding of a large mass ([symbol: see text] 7 cm) in the anterior mediastinum. CT showed a hypodense mass with homogeneous enhancement and calcifications. There was no evidence of invasion in other organs. CT-guided biopsy revealed thyroid tissue. The cervical thyroid was normal in CT, ultrasound and 123I-scintigraphy; no link to the mediastinal goiter was detectable. Radionuclide uptake in the latter was homogeneous. Since malignancy could not be ruled out definitively, the mass was removed by thoracotomy and a vascular pedicle originating from the mediastinum was found. Pathologic evaluation confirmed the preoperative diagnosis of ectopic mediastinal goiter.