Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract and are predominant in the stomach and intestine but rare in the esophagus. Here, we report a case of esophageal GIST which presented as a mediastinal mass on chest X-ray and dyspnea. The case was initially diagnosed as leiomyosarcoma, which could create a diagnostic dilemma. Therefore, recognizing this uncommon presentation as a mediastinal mass with esophageal GIST is important in the differential diagnosis.