In the present case study, we describe a 66 year old male with an atrial myxoma diagnosed eight years after treatment for non-small cell lung cancer. In 2012 he received chemo-radiotherapy (mediastinal area) for stage III-A adenocarcinoma of the lung. In 2020, a left atrial mass was seen on follow-up imaging, with characteristic findings of cardiac myxoma. In addition, diffuse bilateral pulmonary nodules (up to 5 mm in diameter) and left mediastinal lymphadenopathy were noted. In retrospect, the cardiac mass could be seen on a follow-up Computed Tomographic (CT) scan in 2017 within the radiated mediastinal field. The cardiac mass was excised at surgery, and pathologic examination confirmed the diagnosis of myxoma. To the best of our knowledge, this is the first case to be reported of a left atrial myxoma in a patient treated for adenocarcinoma of the lung and the first atrial myxoma reported to occur in a previously irradiated site. 
 
Keywords: Lung adenocarcinoma; Myxoma; Radiotherapy; Rare tumor; Malignant tumor