Esophageal squamous cell carcinoma metastasizing to the oral cavity: a case report and literature review.

Introduction and Importance: Metastatic esophageal carcinoma to the oral cavity has been rarely reported, and most cases were adenocarcinoma metastasizing to the mandible. This first report of a case of metastatic esophageal squamous cell carcinoma to the floor of the mouth is crucial due to its rarity and difficulties in diagnosing and managing this condition. Case Presentation: A 53-year-old male had a painful submucosal mass on the left side of the floor of the mouth for 2 months. A biopsy indicated a moderately differentiated squamous cell carcinoma. Six months before the intraoral mass appeared, the patient had a moderately differentiated squamous cell carcinoma of the thoracic esophagus and was treated with concurrent chemoradiotherapy. With the previous history and pathological review, the diagnosis of metastatic esophageal squamous cell carcinoma to the floor of the mouth was made. Panendoscopy and an 18F-fluorodeoxyglucose positron emission tomography-computed tomography scan revealed no other abnormality or other distant metastasis. The patient underwent surgical resection with postoperative chemoradiotherapy. He was able to take a regular diet and had good speech function. Ten months after treatment completion, he has had recurrent disease at the floor of the mouth with lung metastasis. Conclusions: Oral metastasis from esophageal squamous cell carcinoma is very rare and should be differentiated from primary oral cancer using clinical and pathological features. 18F-fluorodeoxyglucose positron emission tomography-computed tomography scanning is the preferred imaging method to exclude primary tumor persistence and other metastases. Treatment is usually palliative; however, function-preserving surgery may be an option for a patient with limited disease in the oral cavity.