Epithelioid sarcoma: presence of vascular-endothelial cadherin and lack of epithelial cadherin.

To evaluate the pattern of cadherin expression in epithelioid sarcoma. Seven epithelioid sarcomas were immunostained by a polyclonal antibody that detects all cadherin subtypes and by monoclonal antibodies that detect epithelial cadherin (E-cadherin) and vascular-endothelial cadherin (VE cadherin). In addition, the tumours were immunostained for a variety of epithelial (cytokeratin, EMA, AUA1) and endothelial (Factor VIII-related antigen, CD34, CD31) markers. Tumours cells of all seven epithelioid sarcomas expressed cadherins. Surprisingly, E-cadherin was not detected in any of the sarcomas. VE-cadherin was detected in five of seven cases. All seven tumours expressed cytokeratins and EMA but none expressed AUA1. CD34 was detected in six of seven cases and CD31 was detected in a single case. No case expressed Factor VIII-related antigen. Most epithelioid sarcomas strongly express cadherins, a feature which may contribute to their epithelioid appearance. The absence of detectable E-cadherin suggests that epithelial differentiation in these tumours is, at most, incomplete. The expression of VE-cadherin by the majority of cases, in the absence of E-cadherin, is consistent with an element of mesenchymal differentiation, possibly endothelial or perineurial. The additional presence of other markers such as CD34 and CD31 in some cases favours endothelial differentiation.