The left atrium has been opened to reveal the most common primary cardiac neoplasm - an atrial myxoma. These benign masses that arises from remnants of subendocardial vasoformative reserve cells, which are primitive mesenchymal cells that are normally involved in the supportive structure of the endocardium. They most often located in the fossa avails and endocardium of the atrial septum, but can arise on a valve or in a ventricle. They can produce a "ball valve" effect by intermittently occluding the atrioventricular valve orifice. Embolization of fragments of tumor may also occur. Myxomas are easily diagnosed by echocardiography. They may also be seen with chest CT scan and with magnetic resonance angiography. On gross pathology, a gelatinous, irregular surface that fills the left atrium is characteristic finding of myxoma. Common physical examination findings of cardiac myxoma include murmur and abnormal heart sounds that change when the patient changes positions. Complications that can develop are commonly arrhythmias, pulmonaryedema, peripheral emboli, metastasis, blockage of the mitral heart valve. Surgery is the mainstay of treatment for myxomas.