title: A 50-year-old man with incidental cardiac mass.
abstract: A 50-year-old white male with a history of paroxysmal atrial fibrillation presented for transoesophageal echocardiogram prior to atrial fibrillation ablation. However, an echo lucent mass was noted (figure 1A). Colour Doppler and contrast administration showed no flow across the mass or the interatrial septum (see online supplementary videos 1 and 2). CT of the chest demonstrated a thin-walled, well-demarcated mass in the inferior border of the fossa ovalis protruding into the left atrium (figure 1B).
  
  
  
  Which of the following is the most likely diagnosis? Atrial myxomaBronchogenic cystCardiac angiosarcomaHydatid cyst.
authors.affiliation: Department of Cardiovascular Medicine, CHI Health Creighton University School of Medicine, Omaha, Nebraska, USA.
authors.forename: Aiman
authors.identifier: 0000-0002-1584-9934
authors.initials: A
authors.lastname: Smer
authors.affiliation: Division of cardiology, Creighton University School of Medicine, Omaha, Nebraska, USA.
authors.forename: Venkata M
authors.initials: VM
authors.lastname: Alla
authors.affiliation: Omaha, Nebraska, USA.
authors.forename: Hussam
authors.initials: H
authors.lastname: Abuissa
mesh_terms: D001994:Bronchogenic Cyst / Q000000981:diagnostic imaging*; D057791:Cardiac Imaging Techniques; D003937:Diagnosis, Differential; D018618:Echocardiography, Doppler, Color; D017548:Echocardiography, Transesophageal; D006331:Heart Diseases / Q000000981:diagnostic imaging*; D006801:Humans; D033162:Incidental Findings; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D014057:Tomography, X-Ray Computed