A thoracoscopically resected case of mediastinal parathyroid cyst.

A 67-year-old male visited his physician because of a 2-month history of cough and sputum. An abnormal shadow at the left upper mediastinum on chest x-ray film was detected, and the patient was referred to our department for further examination. Chest x-ray film revealed a round shadow at the left upper posterior mediastinum. Computed tomography(CT)revealed a uniform iso density mass about 4 cm in diameter, with a well-defined border. After the intravenous contrast administration, a slight peripheral enhancement was seen around the mass. On magnetic resonance imaging, the mass was hypointense in T1-weighting and hyperintense in T2-weighting. The contrast pattern was the same as that observed in the CT scan. On sagittal and coronal sections, the mass was adjacent to the aortic arch. Although a benign tumor was mostly suspected based on imaging findings, a malignant tumor was also possible. Accordingly, we resected this mass with video-assisted thoracoscopy. Findings at operation were a cystic mass. The pathological findings were compatible with benign parathyroid cyst, which was suspected to be the cystic degeneration of a parathyroid adenoma.