Carcinosarcoma of the oesophagus with rhabdomyoblastic differentiation

We report a case of oesophageal carcinosarcoma with prominent rhabdomyoblastic differentiation. Immunohistochemically, the rhabdomyblasts were mainly reactive to vimentin, cytokeratin, desmin, muscle‐specific actin, myosin, and myoglobin, and were surrounded by laminin and type IV collagen‐positive basement membranes. The tumour had dual differentiation, carcinomatous and sarcomatous, but also showed evident features of transition between the two components, suggesting a common origin. An epithelial‐mesenchymal conversion could be the pathogenetic mechanism involved in the histogenesis of this lesion. The word carcinosarcoma, from a descriptive point of view, seems the most suitable to describe a tumour composed of both carcinomatous and true sarcomatous elements.