A rare case report of accessory thyroid in the superior mediastinum in the form of multinodular goiter

Retrosternal expansion of a goiter is one of the most common types of mass in the upper mediastinum. Although there is no clear definition of retrosternal, substernal, or mediastinal goiter in the literature, it usually refers to an extension of thyroid tissue from the cervical part that continues to the anterior mediastinum of the aortic arch. One of the interesting features of these cervical mediastinal lesions is that they may not be continuous. Such goiter types classically present with compression symptoms such as dyspnea, dysphonia, dysphagia, or sleep apnea, and less frequently, these masses can compress neurovascular structures, leading to superior vena cava (SVC) syndrome and Horner’s syndrome. In our case report, A 47-year-old female from North Karnataka presented to the hospital with history of dyspnea, dysphonia, and dysphagia persisting for the last 3 years. After careful examination and investigation, a diagnosis of thymoma was made initially. However, upon biopsy of the excised tumor, unexpected finding was revealed, it was identified as a multinodular goiter (MNG) rather than a thymoma.