Right atrial primary cardiac osteosarcoma.

A previously healthy 14-year-old boy with an atypically located primary cardiac osteosarcoma filling the right atrium with significant extension into both systemic and pulmonary venous structures presented with a clinical picture of heart failure. Imaging showed a large right atrial mass with posterior extension into right pulmonary veins and inferior extension into the inferior vena cava causing near total obstruction of systemic venous return to the heart. Bone marrow biopsy showed no evidence of marrow involvement by metastatic malignancy. Histopathology was a high-grade osteosarcoma. Partial tumor debulking was achieved via right atriotomy.