Tehran University of Medical Sciences The Research in Heart Yield and Translational Medicine (RHYTHM) 3115-7270 15 1 2020 01 29 35 38 Arezoo Zorufian Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran. Mahmoud Shirzad Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran. Narges Shahbazi Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Saheb Jam Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran. Zahra Rahnamoun Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran. Shapoor Shirani Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran. Tahereh Davarpasand Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran. 2019 03 02 2019 12 14 Nowadays, the early diagnosis of tumoral diseases is more possible and accurate with multiple diagnostic imaging modalities such as chest X-ray, echocardiography, computed tomography, and magnetic resonance imaging, especially for cardiac tumors which are usually asymptomatic, even in large sizes. In cardiac masses, the patients’ presentations are non- specific and dependent on the tumor size and site as well as its compressive effect on the adjacent structures. On the other hand, the first and last signs could be sudden cardiac death. However, cardiac masses are either benign or malignant and metastatic in their malignant type, and their definite diagnosis is only possible by surgical tumor resection and tissue biopsy. In this paper, we describe an old patient with severe pericardial effusion and an unusual intrapericardial tumor in transthoracic echocardiography, representing a rare case of a giant ectopic thymoma after surgical resection and pathologic assessment. https://rhythm.tums.ac.ir/index.php/jthc/article/view/1049 https://rhythm.tums.ac.ir/index.php/jthc/article/download/1049/893