The patient is a 74-year-old white woman with a 2-month history of dysphagia. Evaluation with barium swallow first identified an extrinsic compression in the upper to middle third of the esophagus. Magnetic resonance imaging (MRI) showed the mass extended to the midline posteriorly and was compressing the esophagus. The left lobe of the thyroid gland appeared larger than did the right, and a question of connection to the left lobe existed (Fig. 1). A computed tomography (CT) scan confirmed a posterior mediastinal mass with no cervical connections (Fig. 2), The physical examination revealed no abnormalities. Thyroid studies, hematologic panels, and chemistry panels were normal. Operation proceeded. A right posterolateral thoracotomy incision allowed visualization of the mass beneath the pleura. Mobilization of the mass encountered no communication with the cervical thyroid, and all blood supply to the mass was intrathoracic. The specimen was soft, tan, and measured 10 3 7 3 3 cm (Fig. 3). Histologic examination was representative of multinodular goiter.