The most common causes of mediastinal masses are thymomas, lymphomas and neuromas. Mediastinal cysts, such as bronchogenic cysts, which are usually benign, are less common. We report the case of a 59-year-old woman with a history of progressive dysphagia. A computed tomography scan  revealed a cystic lesion in the anterior mediastinum. The cyst was surgically resected and turned out to be a benign parathyroid cyst. The patient's symptoms disappeared after surgical removal. Both the serum calcium and parathyroid hormone levels were normal before, and after surgery. Parathyroid cysts are rare lesions of the mediastinum and only around 100 cases have been reported in literature. Here we report the first case of a mediastinal parathyroid cyst in Iceland.

Figure 1: A computed tomography scan showed a well-circumscribed low density tumor in the anterior mediastinum.

Figure 2: An MRI of the thorax and neck showing a cystic lesion.

Figure 3: The cyst (star) compresses the trachea (red arrow) and the oesophagus (yellow arrow).

Figure 4: The cyst was surgically resected through a incision on the neck (a). A photograph of the surgical specimen (b).   

Figure 5: Microscopic analysis of the specimen. On the left the H&E stain showes clusters of cells with round nuclei and an eosinophil or clear cytoplasm simmilar to parathyroid chief cells and oxyphil cells. Immunohistochemical staining of these cells (right) was positive for PTH confirming that the specimen was made up of parathyroid tissue.