Intracardiac Extension of Lung Carcinoma Presenting as an Atrial Myxoma: A Case Report

Left atrial (LA) mass is most commonly presumed to be a cardiac myxoma, as it is approximately 75% of primary cardiac tumors, with a strong predilection for the LA. In rare instances, primary lung carcinoma may extend to the LA, creating an intracardiac mass indistinguishable from a myxoma on initial echocardiographic assessment. We report a Persian 73-year-old man with progressive dyspnea and a left atrial mass initially suspected as a myxoma. Echocardiography and CT revealed extension of a pulmonary tumor into the atrium through the pulmonary vein. This case highlights the diagnostic and treatment challenges of intracardiac extension, which is rare but should be considered by the cardiologist.