Ectopic Kidney Mimicking an Inferior Vena Cava Mass in a Patient with Cardiac Myxoma and Atrial Septal Defect.

An ectopic kidney (EK) and cardiac myxoma are two distinct conditions with no known direct association. Cardiac myxoma represents the most common benign primary cardiac tumor, arising from the endocardium. In contrast, an EK is a congenital anomaly characterized by one or both kidneys being located outside their normal position within the renal fossa. We present the case of a 27-year-old female patient who was evaluated for ischemic stroke and was found to have a left atrial myxoma originating from the interatrial septum (IAS) and prolapsing into the right atrium through an atrial septal defect (ASD). During transthoracic echocardiographic (TTE) evaluation, a hypoechogenic structure suggestive of a mass was observed within the inferior vena cava (IVC). However, multimodality imaging, including contrast-enhanced computed tomography (CT), demonstrated that this finding represented external compression caused by a right EK rather than a true intravascular mass. This case underscores the importance of multimodality imaging in distinguishing true intravascular lesions from external anatomical impressions and highlights that an EK may mimic an IVC mass on echocardiography. Furthermore, the report documents a rare concurrence of cardiac myxoma, ASD, thoracic EK, and an ectopic adrenal gland.