Abstract
Primary cardiac malignancies are rare, with cardiac sarcomas being the main type. Among these, intimal sarcomas are the most common. However, they tend to occur in the great vessels and are rare in the heart, with only a few isolated cases reported. We report a challenging case of a patient with left atrial intimal sarcoma with rhabdomyosarcoma differentiation. The patient was admitted after a physical examination detected left heart occupancy, and initial imaging suspected a left atrial thrombus. The patient then underwent extracorporeal circulation-assisted open cardiac surgery with resection of an atrial mass. The postoperative pathological findings were suggestive of an arterial intimal sarcoma, which included areas of rhabdomyosarcoma differentiation within the tumor tissue. Unfortunately, the patient's tumor recurred 4 months later, and she died due to treatment failure. This case highlights the rarity and risk of misdiagnosis of cardiac intimal sarcoma. Additionally, we aim to improve the understanding of intimal sarcoma through a review of immunohistochemistry and gene amplification techniques.