Introduction and importance: The mediastinal ectopic thyroid gland is rare and usually asymptomatic. Ectopic thyroid tissue has malignant potential, but ectopic thyroid cancers are extremely rare, particularly mediastinal thyroid cancer, with only five cases reported in the literature.
Case presentation: A 73 years-old male patient diagnosed with multinodular goitre with two FLUS cytology was summited to an uneventful total thyroidectomy. Pathology revealed 8 synchronous papillary carcinomas in both thyroid lobes. Follow-up identified persistent elevation of thyroglobulin. A cervical ultrasound and cervical and thoracic CT scan were performed, identifying a mediastinal tumour of 6 × 3 cm. Resection was performed by video-assisted thoracic surgery (VATS). Pathology identified an ectopic mediastinal thyroid with a 4 mm papillary microcarcinoma. Recovery was uneventful and the patient is currently asymptomatic.
Clinical discussion: There is no consensus on the best treatment strategy for mediastinal ectopic thyroid, but surgical resection is advised as being the only method allowing for a complete cure. Although both thoracotomy and sternotomy approaches have been usually used for mediastinal thyroid tumours resection, the thoracoscopic approach has been used with good results in recent years. Thoracoscopy has better visualization, less morbimortality, and faster recovery. Giant masses (>10 cm) are the only limitation for VATS.
Conclusion: Ectopic mediastinal thyroid is extremely rare, and its malignant transformation is even rarer. There is no consensus on the best treatment strategy, but surgical resection of the mediastinal thyroid is advised. VATS is a safe and feasible minimally invasive technique with good outcomes.
Keywords: Ectopic thyroid; Mediastinal thyroid; Papillary carcinoma; VATS.
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