Extension of a pulmonary blastoma into the left atrium.

Pulmonary tumors of embryonic origin are rare, and pulmonary blastomas are probably the most uncommon. A thorough literature search disclosed no previous reports of extension of this type of tumor into the heart. We describe a patient whose initial clinical presentation suggested an obstructive left atrial mass; however, clinical and histologic findings indicated the mass was a tumor that originated from a pulmonary blastoma that extended into the left atrium through a pulmonary vein. The unique aspect of this case is that the patient's symptoms were related to the obstructive effects of the atrial mass, not to the primary pulmonary tumor.