Benign cardiac tumors of the pluripotent mesenchyme.

Among benign primary cardiac tumors, myxomas and papillary fibroelastomas are the most common. Cardiac myxomas arise from pluripotent mesenchymal cells and are seen as intracardiac, glistening polypoid masses arising most frequently from the interatrial septum in the left atrium. They are composed of stellate to polygonal myxoma cells in a mucopolysaccharide-rich matrix. These tumors can be sporadic or familial. On the other hand, papillary fibroelastomas are sporadic, seen as a mass of delicate papillary fronds ("sea anemone"-like) arising from a slender stalk, commonly located on diseased left-sided valves. They are lined by plump endothelial cells, which rest on stalks composed of mucopolysaccharides enclosing a collagen- and elastin-rich core. Embolism is often the mode of presentation for both of the tumors; myxomas are also associated with obstructive and constitutional symptoms. In contrast, neurogenic tumors (paraganglia or nerve sheath tumors) are exceedingly rare and occur as epicardial and infrequently as intracatdiac masses. The tumors are often incidentally diagnosed by the usual echocardiography, but magnetic resonance imaging is useful for further characterization of the tumors. The tumors are, in general, treated by surgical resection, but may require a little or at times more significant reconstruction. Among these tumors, the myxomas are associated with a higher rate of recurrences.