Adenoid squamous cell carcinoma has been accepted to be an uncommon variant of squamous cell carcinoma and a definite entity. Adenoid squamous cell carcinoma is characterized by a mixture of squamous components with adenocarcinomatous elements, which result from acantholytic phenomena in the tumor. We describe an extremely rare case of synchronous double cancer involving adenoid squamous cell carcinoma of the lower gingiva and squamous cell carcinoma of the esophagus in a 75-year-old man. Intraoral examination revealed a tumor measuring 30×25×7mm in the lower gingiva near the left second molar and the buccal mucosa. Biopsy revealed adenoid squamous cell carcinoma. On preoperative endoscopic examination, esophageal cancer was detected and histologically diagnosed as squamous cell carcinoma. The patient died of uncontrolled adenoid squamous cell carcinoma.
