Primary intermediate-grade cardiac myxofibrosarcoma with osseous metaplasia: an extremely rare occurrence with a previously unreported feature.

Primary cardiac myxofibrosarcoma (MFS) is a very rare cardiac tumor with no more than 22 cases reported in the literature, including our case. We report an MFS arising in the left atrium in a 65-year-old woman who presented with pneumonia and cardiac failure. The 9.5-cm mass was diagnosed by echocardiogram. Histopathology examination showed an intermediate-grade MFS with osseous metaplasia, a feature that has not been reported before.