Ectopic posterior mediastinal thyroid: a case report
© Karapolat and Bulut; licensee BioMed Central Ltd. 2008
Received: 01 July 2008
Accepted: 21 July 2008
Published: 21 July 2008
Posterior mediastinum is a very rare site of ectopic thyroid and such cases are usually identified incidentally by radiography.
A 74 year-old Caucasian male was operated for a mass located in the right posterior mediastinum. Diagnosis of thyroid tissue was confirmed intra-operatively by frozen section and the mass was resected totally. He is well without any problems for 1 year after operation.
Surgical resection may deliver a cure for ectopic posterior mediastinal thyroid and offers good prospects for prognosis.
Ectopic posterior mediastinal thyroid is a rare clinical entity. It comprises some 1% of all mediastinal tumors . Because of silent clinical findings, it is difficult to diagnose clinically. Therefore, they remain asymptomatic for many years, until the mass becomes larger in size. The purpose of this paper was to report this case of ectopic thyroid because of its rarity.
Neurogenic tumors, Castleman disease, bronchogenic cysts, Bochdalek's hernia and mesenchymal tumors comprise a great proportion of masses localized in the posterior mediastinum. Though seen rarely, ectopic posterior mediastinal thyroid should also be included in diagnostic possibilities.
It is a benign condition and localized either retrotracheally or retroesophageally. In general, it occurs due to descent of a posterolaterally enlarging inferior pole of the thyroid gland. There may be a displacement in thyroid tissue due to their connection with these during the migration of large vessels in embryogenesis .
Ectopic posterior mediastinal thyroid is often asymptomatic. Patients are usually euthyroid. However, symptoms related to the compression on adjacent organs, cough, dyspnea, wheezing, dysphagia, and obstruction of the superior vena cava may be seen. Occasionally, acute tracheal obstruction and severe respiratory failure may be observed . It is usually diagnosed incidentally during radiological procedures performed for other reasons, as in our case.
True malignant transformation in ectopic thyroid tissue is extremely rare . Nevertheless, these masses should be resected surgically due to the risks of malignant transformation, progressive enlargement, hemorrhage within the mass causing respiratory failure, and compression of neighbouring vital mediastinal organs. In the surgical approach, thoracotomy provides both surgical convenience and allows a complete resection with easy access and better visualization. This is a safe procedure with a very low mortality rate and an acceptable morbidity. Finally, complete resection is necessary for achieving a cure.
It usually gets anomalous blood supply from the major great vessels in thorax, especially from the aorta and may show adhesions to surrounding tissues. Therefore, these arterial structures must be ligated and dissection should be performed carefully not to injure the vital organs such as the trachea and the esophagus. In our case, right recurrent laryngeal nerve was adhered to the mass inferiorly and the mass was removed after the nerve was carefully separated from it. Blunt digital dissection without visual control may damage this nerve neighboring the mass and cause vocal cord paralysis postoperatively.
Although ectopic posterior mediastinal thyroid is a rare entity, it must be considered in the differential diagnosis of posterior mediastinal masses. Surgery is the treatment of choice and prognosis is excellent following complete resection.
Written informed consent was obtained from the patient for the publication of this case report and for the use of images. A copy of the written consent is available for the Editor-in-Chief of this journal.
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