Oesophageal squamous cell carcinoma mimicking submucosal tumour.

<bold>Background: </bold>Oesophageal submucosal tumours are usually benign. We report a rare case of esophageal squamous cell carcinoma presenting as a submucosal tumour.<bold>Case Presentation: </bold>A 58-year-old man undergoing screening oesophago-gastroduodenoscopy was found to have a smooth-surfaced 0.6-cm sized submucosal tumour in the oesophagus 30 cm from the incisor. Endoscopic ultrasonography showed the tumour to be located in the muscularis mucosa; the lesion was heterogeneously hypoechoic and had a clear boundary. With a provisional diagnosis of leiomyoma, the tumour was removed by endoscopic submucosal dissection. Pathological examination showed it to be a moderately differentiated infiltrating squamous cell carcinoma, with normal overlying squamous epithelium. Immunohistochemistry indicated that it was caused by malignant transformation in mucosal glandular duct epithelium. Positron emission tomography-computer tomography showed no tumour spread to any other site. The patient was treated by oesophageal resection.<bold>Conclusion: </bold>The clinician should be aware that oesophageal submucosal tumours with smooth overlying mucosa may not always be benign; malignancy must be ruled out. [ABSTRACT FROM AUTHOR]