Castleman disease is a relatively rare disorder of lymphoid tissue that involves the gastrointestinal tract in a variety of clinical and pathologic manifestations. A submucosal location has never been described in the medical literature. We report a case of esophageal Castleman disease involving the submucosal layer in a 62-year-old man, which was confirmed on pathology. Esophagography and CT demonstrated an intramural tumor, and a leiomyoma or leiomyosarcoma was suspected based on the known incidence of such tumors.