Primary cardiac osteosarcoma with imaging that revealed no calcification.

Osteosarcoma is a rare primary cardiac malignancy. Calcification on imaging is crucial to differentiating osteosarcoma, but we encountered a case that was difficult to diagnose because imaging revealed no calcification. A 67-year-old man was admitted for heart failure. Echocardiography demonstrated mitral regurgitation and a mass in the left atrium. A cardiac malignancy was suspected. Computed tomography revealed no calcification. Operation was performed, and histopathological examination identified the tumor as an osteosarcoma.