The case was a 67-year old male with a past history of gastrectomy due to gastric ulcer. Upper gastrointestinal tract endoscopy for follow up in 1995 showed an erythematous, slightly depressed lesion in the middle thoracic esophagus. Biopsy specimen disclosed dysplasia. Follow up endoscopy in November 1997 showed a round, elevated lesionwith a central erythematous elevation which was not stained by iodine spray. The central elevation had depressed during ultrasonic endoscopic examination after admission, which disclosed poorly-differentiated squamous cell carcinoma with sarcomatous element. No transitional zone was found between squamous cell carcinoma lesion and sarcomatous lesion. Immunohistochemistrical staining disclosed that the sarcomatous component was negative for epithelial membranous antigen and positive for vimentin, which demonstrated the elevated lesion as pseudosarcoma. The patient underwent subtotal thoracic esophagectomy after chemotherapy. Histological examinasion of the resected specimen showed that the remaining tumor invaded the muscularis propria with no metastatic lymph nodes. We have reported a rare case of carcinosarcoma presumably classified as pseudosarcoma.
