Primary Intimal (Spindle Cell) Sarcoma of the Left Atrium

Mini‐Abstract A previously healthy 50‐year‐old man presented to our hospital with a history of progressive shortness of breath and diminished exercise tolerance for 3 months. A transthoracic echocardiogram was interpreted as showing a left atrial mass that was mobile and protruding into the left ventricle and noted that it was “like a myxoma, though its attachment was not visualized.” He was taken to the operating room with the initial diagnosis of left atrial myxoma, but upon surgical inspection of the left atrium, it was noted that the appearance of the tumor was more suggestive of malignancy. Pathologic examination revealed sheets of high‐grade densely packed spindle cells replacing and infiltrating into the atrial wall.