Granular cell tumor of the esophagus.

A case of granular cell tumor of the esophagus in a 50-year-old man is reported. Gastrointestinal endoscopy revealed a round, sessile, non-ulcerated white-yellow elevated tumor at the lower third of the esophagus. Biopsy revealed a granular cell tumor. Immunohistochemical staining demonstrated that granules in the cytoplasm of tumor cells were positive for S-100 protein and negative for carcinoembryonic antigen. An electron microscopic study revealed that tumor cells were closely packed in clusters, surrounded by basal lamina and collagen fibers. Most cells contained dark cytoplasm filled with electron-dense granules. These granules resembled lysosomes and phagosomes. In a few cells with clear cytoplasm, some mitochondria and poorly developed endoplasmic reticulums were seen. Fibrillar internal materials, myelin-like figures and a premature angulate body were observed in the clear cytoplasm. The lesion has remained unchanged in gross appearance and in size for twenty-three months without any treatment.