The radiographic differential diagnosis of the posterior mediastinal mass in the present case includes neurogenic tumors (eg, neurilemoma/schwannoma, neurofibroma, ganglioneuroma/ganglioneuroblastoma, neuroblastoma, and paraganglioma) and esophageal disease (eg, esophageal duplication cyst and primary esophageal neoplasm). Schwannoma of the right recurrent laryngeal nerve was the primary preoperative consideration, based on the uniform enhancement of the mass and its location in the tracheoesophageal groove. However, a computed tomography–guided biopsy of the mass revealed normal thyroid tissue that was completely separate from the thyroid gland. The computed tomographic scan also showed that the tissue was completely separate from the thyroid gland.