RÉSUMÉ
Transformation of a poorly differentiated squamous cell carcinoma [SCC] of the esophagus into a [carcinosarcoma] of the pleura and lung has never been reported and its histogenetic origin is still debated. A 48-year-old man was admitted due to progressive dysphagia and a weight loss of 5 kilograms within 2 months. Upper gastrointestinal panendoscopic biopsy revealed poorly differentiated SCC of thoracic esophagus, upper third, T4N1M1 a, stage IVa. He received concurrent chemoradiotherapy [CCRT]. About 9 months later, rapid progression of lung metastases and pleural effusion were found. According to the histopathological and immunohistochemical stain results, carcinosarcoma was diagnosed. Palliative therapy was given and the patient eventually died of the disease 9 months after SCC of the thoracic esophagus was diagnosed and one month after carcinosarcoma of the pleura and lung were confirmed