NBME Form 16 Practice Test

A left atrial myxoma is typically a mobile, friable mass that sits near the mitral valve. Because it can intermittently prolapse into the mitral orifice during diastole, it often causes obstruction to left ventricular filling, producing symptoms that mimic mitral stenosis—dyspnea, orthopnea, and sometimes syncope or other signs of left-sided heart failure. At the same time, its friable surface can shed tumor fragments into the systemic circulation, leading to embolic phenomena such as transient ischemic attacks or strokes, and emboli to kidneys, spleen, or limbs. So the combination of embolic events with obstructive symptoms best captures the classic presentation. Other features like severe anemia or renal failure aren’t typical primary presentations, and pulmonary hypertension isn’t the hallmark since this mass tends to cause systemic rather than pulmonary emboli.