Minute esophageal granular cell tumor: a case report with immunohistochemical and ultrastructural examination

A small granular cell tumor (GCT) of the esophagus, which developed in a 44-year-old Japanese man and was removed by endoscopic polypectomy, is presented. Histopathologically, the tumor, located in the submucosa, was composed of uniform neoplastic cells with nuclei and abundant round or oval cytoplasm containing eosinophilic granules. An immunohistochemical examination showed positive reactions with S-100 protein, especially the beta subunit, and neuron specific enolase in the neoplastic cells. Electron microscopic observation revealed abundant electron-dense or light granules and myelin-like structures in the cytoplasm. These findings support the concept that esophageal GCT is derived from Schwann cells.