Esophageal carcinosarcoma is a rare tumor composed of neoplastic squamous epithelium and sarcomatous spindle cells. The origin of spindle cells remains unknown; however, the majority of sarcomatous components are currently considered to be derived from existing carcinomatous cells via epithelial-mesenchymal transition (EMT). We report a case of esophageal carcinosarcoma harboring basaloid squamous cell carcinoma successfully treated with preoperative chemotherapy. A 78-year-old man complaining dysphagia was diagnosed as esophageal carcinosarcoma. After two courses of preoperative chemotherapy with cisplatin and 5-fluorouracil, curative esophagectomy with lymph node dissection was performed thoracoscopically. Histopathological findings of the resected specimen revealed the mixture of basaloid squamous cell carcinoma and sarcomatous spindle cells. A transitional zone between both components was also detected. As fibrosis was identified around both two components, the findings indicated that both carcinomatous and sarcomatous neoplasms disappeared by preoperative chemotherapy. Final pathological diagnosis was esophageal carcinosarcoma with basaloid squamous cell carcinoma. No recurrent lesions have been detected for 25 months after the surgery. Sarcomatous spindle cells could be derived from the components of basaloid squamous cell carcinoma in our present case due to the presence of histological transition between two components. In addition, the marked immunoreactivity of vimentin (an EMT marker) detected in the tumor cells of basaloid squamous cell carcinoma could be consistent with the concept of monoclonal origin via EMT. The regimen targeting squamous cell carcinoma could also be effective in the treatment of sarcomatous components. Preoperative therapy might achieve the improvement of clinical outcome of patients with esophageal carcinosarcoma.
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