Giant-cell-rich myxoma of right atrium. An ultrastructural analysis.

Myxoma is the commonest primary tumor of the heart, arising more frequently in the left than the right atrium. Here, we report a case of right atrial myxoma, arising close to the entry of the inferior vena cava, which is rich in multinucleated giant cells. No glandular elements were identified. Ultrastructural analysis of the giant cells was carried out, which revealed these giant cells to be of similar morphology as the mononuclear cells, suggesting their formation by fusion of individual tumor cells. Immunostain for Vimentin and Desmin showed positivity in the giant cells as well as cells with single nucleus, further confirming these observations.