We report a case of oesophageal carcinosarcoma with prominent rhabdomy
oblastic differentiation. Immunohistochemically, the rhabdomyblasts we
re mainly reactive to vimentin, cytokeratin, desmin, muscle-specific a
ctin, myosin, and myoglobin, and were surrounded by laminin and type I
V collagen-positive basement membranes. The tumour had dual differenti
ation, 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 mechan
ism involved in the histogenesis of this lesion. The word carcinosarco
ma, from a descriptive point of view, seems the most suitable to descr
ibe a tumour composed of both carcinomatous and true sarcomatous eleme
nts.