A collision tumor of esophagus.

The collision tumor is defined by Meyer as that arisen from the accidental meeting and eventual intermingling of two independent neoplasms, which is quite rare. Most of them occur in the junction of different epithelial types of tissue such as oral cavity, esophagogastric junction, anorectaljunction and cervix, while collision tumors occurring in the liver, gallbladder, pancreatic, urinary bladder also have been reported. Here we present a case of 55-year-old Chinese man diagnosed as a collision tumor composed of leiomyosarcoma and squamous cell carcinoma (SqCC) in the lower third part of esophagus with 6 years survival after surgery and radiotherapy.