Abstract Body (Do not enter title and authors here): Introduction: Lung cancer is divided broadly into two main types: Small cell lung cancer (SCLC) and non-small cell lung cancer-NSCLC. Approximately 70% of SCLC cases have metastasized to other parts of the body including lymph nodes, bone, liver, adrenal glands, and brain [1]. SCLS metastasis to cardiac tissue is rare. Primary cardiac tumors are as rare with a reported prevalence of 0.028% [2]. Here we present a 59-year-old female (59F) with recurrent SCLC metastasis with evidence of a newly diagnosed primary cardiac tumor.

Case Presentation: 59F with a past medical history of SCLC status-post chemotherapy and radiation presented for evaluation of worsening left upper extremity pain, paresthesia, motor weakness, and neck pain. During the hospital admission, an echocardiogram demonstrated extensive thrombus from the Superior Vena Cava (SVC) into the right atrium (RA) and an irregular echogenic 37 mm x 26 mm mass partially attached to the posterior leaflet of the tricuspid valve. The RA mass was successfully removed by mechanical thrombectomy. Pathological results of the RA mass revealed significant malignant epithelioid and spindled neoplasm with myxoid stroma– concerning for myoepithelial disease.

Discussion: Cardiac tumors, although uncommon, should be included in the list of possible diagnoses when observing any abnormal mass detected through cardiovascular or thoracic imaging techniques. Cardiac tumors are likely due to metastatic origins as metastatic cardiac tumors occur 20 times more frequently than primary cardiac tumors[3].When metastatic cardiac tumors are suspected, malignant melanoma and leukemia are the most frequent origins[4]. Rarely does SCLC metastasize to cardiac tissue. Primary cardiac tumors are typically benign (90%), with primary malignant tumors being very rare[5]. Patients may be asymptomatic, or present with nonspecific symptoms such as exertional dyspnea, fevers, arthralgias, or life-threatening cardiac tamponade[6]. For right atrial tumors, treatment strategies are usually dependent on symptomatology, in which removal via aspiration or surgical resection has demonstrated a favorable prognosis[7].

Conclusion: Given the rarity of primary cardiac tumors in the setting of metastatic SCLC, there exist no evidence-based guidelines for optimal management of right atrial tumors. In our patient, mechanical aspiration was performed without complications and prevented potential adverse cardiopulmonary events from occurring.