ESOPHAGEAL CARCINOSARCOMA - A GENETIC-ANALYSIS

Carcinosarcoma of the esophagus is a rare malignant neoplasm that cons ists of both carcinomatous and sarcomatous elements. The histogenesis of the sarcomatous component is generally considered to result from me taplasia of carcinomatous cells toward mesenchymal differentiation, Tr ue carcinosarcoma, characterized as a collision between a carcinoma an d a sarcoma, is extremely rare, We describe a patient with primary ach alasia who developed a true carcinosarcoma of the esophagus in which c lonal differences between carcinomatous and sarcomatous elements were genetically and immunohistochemically demonstrated. A polypoid tumor l ocated in the middle third of the esophagus developed in a 51-year-old man with longstanding achalasia. The tumor was predominantly composed of spindle-shaped sarcomatous cells, Squamous cell carcinoma in situ and islands of well-differentiated squamous cell carcinoma in the sarc omatous element were histologically observed. The sarcomatous element was immunoreactive for both mesenchymal and myoid markers. The carcino matous component expressed type I and type II cytokeratins as well as epithelial membrane antigen, Analysis for chromosomal loss of heterozy gosity performed in multiple microdissected samples of each sarcomatou s and carcinomatous element revealed distinct genetic clonalities. The se differences in immunohistochemical and genetic clonalities suggest that the tumor composed of squamous cell carcinoma and leiomyosarcoma originated separately from epithelial and mesenchymal precursors.