A midline sternotomy revealed a large lobular mass (Fig 1) arising out of the left ventricle, infiltrating the myocardium and extending into the anterior and superior mediastinum. Due to the extent of tumor infiltration, it was considered inoperable. The biopsy showed a tumor with intermingled dense, compact cellular and loose myxoid areas. The cellular areas are predominantly seen around dilated blood vessels, and composed of sheets of small spindled to round cells with hyperchromatic, round nuclei. The biopsy and immunohistochemistry analysis were consistent with a diagnosis of spindle cell rhabdomyosarcoma.