70-year-old woman with left atrium mass   

History and images

Our appreciation is extended to Dr. Abdul Abid, University of Texas Medical Branch, for contributing this case.

History: A 70-year-old woman with a history of stroke was found to have a 1.5 x 1.0-cm mass in her left atrium, roughly attached to the edge of the left atrial appendage. A surgical excision was performed, and surgeons suspected the mass to be a myxoma. It was attached to the aortic valve.

Click the images to enlarge.

What is the most likely diagnosis?
Atrial myxoma
Papillary fibroelastoma
Cardiac rhabdomyoma
Thrombotic endocarditis

Which special or immunohistochemical stain would help with the diagnosis?
Thyroid transcription factor-1 (TTF-1)