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

The immunohistochemical profile of cardiac myxoma has been debated. The tum or is thought to be derived from multipotential undifferentiated mesenchyma l cells. A consistent marker for this tumor has not been found. In this art icle an immunohistochemical study of 23 cardiac myxomas was accomplished. T his study comprised the immunoreactivity of the tumors for thrombomodulin, calretinin and and c-kit (CD117). To the best of our knowledge, thrombomodu lin and c-kit have not been tested in cardiac myxoma. Calretinin expression has been recently demonstrated in cardiac myxoma, although this finding ha s not been yet validated. Surface lining cells, tumor vascular endothelium, cells around the vascular slits and stromal cells embedded in the myxoid m atrix were assessed independently. All tumors showed reactivity for thrombo modulin 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 cardi ac myxomas expressed calretinin in the stromal cells and in the perivascula r 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.