Thrombomodulin, calretinin and c-kit (CD117) expression in cardiac myxoma.

The immunohistochemical profile of cardiac myxoma has been debated. The tumor is thought to be derived from multipotential undifferentiated mesenchymal cells. A consistent marker for this tumor has not been found. In this article an immunohistochemical study of 23 cardiac myxomas was accomplished. This study comprised the immunoreactivity of the tumors for thrombomodulin, calretinin and and c-kit (CD117). To the best of our knowledge, thrombomodulin and c-kit have not been tested in cardiac myxoma. Calretinin expression has been recently demonstrated in cardiac myxoma, although this finding has not been yet validated. Surface lining cells, tumor vascular endothelium, cells around the vascular slits and stromal cells embedded in the myxoid matrix were assessed independently. All tumors showed reactivity for thrombomodulin in the surface cells and in the endothelium of neoplastic vessels. 82.6% of cardiac myxomas expressed thrombomodulin in the stromal cells and 69.6% of the tumors were reactive in the perivascular cells. 73.9% of cardiac myxomas expressed calretinin in the stromal cells and in the perivascular cells. All myxomas were negative for c-kit. Thrombomodulin and calretinin may be important diagnostic aids for cardiac myxoma. Cardiac myxoma cells do not express embryonic/fetal endothelial antigens.