Immunohistochemical expression of endothelial markers in left atrial myxomas: a study of six cases.

Vascular endothelial cells are antigenically heterogeneous and therefore it has been recommended that a range of immunohistochemical markers is employed to show the presence of cells of endothelial origin in surgical pathology. In this study we applied three monoclonal antibodies--to factor VIII-related antigen, JC70 (CD31), QBend 10 (CD34)--and Ulex europaeus agglutinin type 1 lectin (UEA-1), to six consecutive cases of left atrial myxoma. We found that JC70 and QBend 10 consistently stained myxoma cells in all their different growth patterns contrasting with factor VIII-related antigen expression and UEA-1 binding which were restricted to areas which showed morphological evidence of vascular differentiation. These findings suggest that the constituent cells of atrial myxomas show more widespread endothelial differentiation than has previously been recognized and that differences in immunohistochemical staining may reflect the maturation status of these cells.