An Unusual Presentation of Metastatic Soft Tissue Sarcoma to the Left Atrium and Pulmonary Veins: A Case Report and Comprehensive Literature Review

Metastatic soft tissue sarcoma ( STS ) is a rare and aggressive malignancy arising from connective tissues. It is characterized by its ability to metastasize to distant sites, with the lungs being the most common location. Despite advances in diagnosis and treatment, the prognosis remains poor, particularly in cases with advanced metastasis. Management often involves a multidisciplinary approach, combining surgery, radiotherapy, chemotherapy, and newer targeted therapies. This report highlights an unusual case of STS metastasizing to the left atrium ( LA ) and pulmonary veins, which presented with complex clinical and therapeutic challenges. We report the case of a 74‐year‐old male with a history of synovial cell sarcoma of the left elbow, initially treated with wide resection surgery and adjuvant radiotherapy. Eight months post‐treatment, bone metastasis to the ipsilateral humerus bone was detected and managed surgically. The patient later presented with sudden‐onset numbness and weakness on the left side, along with sudden‐onset aphasia, raising suspicion of neurologic or embolic complications. Diagnostic evaluation, including transthoracic echocardiogram ( TEE ) and chest computed tomography, revealed a large mass in the LA and pulmonary vein, consistent with metastatic sarcoma. Open‐heart surgery was performed to resect the tumor palliatively. Adjuvant chemotherapy and radiotherapy were initiated. Follow‐up demonstrated stability of the disease for up to 1 year under the treatment protocol.