[A Case of Esophageal Submucosal Tumor Undiagnosed Preoperatively and Treated with Thoracoscopic Enucleation].

An asymptomatic 35-year-old man visited our hospital because of an esophageal abnormality identified on a medical check-up. Gastrointestinal endoscopic examination revealed a 4 cm diameter submucosal tumor(SMT)in the upper esophagus. endoscopic ultrasound fine-needle aspiration biopsy(EUS-FNAB)was performed. Histopathological examination showed that it was strongly positive for a-SMA and partially positive for c-kit. An esophageal leiomyoma was suspected but esophageal gastrointestinal stromal tumor(GIST)could not be completely ruled out. After considering the patient's age and the location of the tumor, we performed thoracic enucleation of the esophageal SMT. Immunostaining findings showed that it was a-SMA positive and S-100 negative. Mast cells, but not tumor cells were partially stained with c-kit. The final pathological diagnosis was leiomyoma. The postoperative course was uneventful. We report this case together with a review of the literature.