A teratoma within the heart. Most commonly, these tumors are detected in the pericardial cavity attached to the pulmonary artery and aorta. The tumor size within the heart varies from 2 to 9 cm in diameter, and intrapericardial tumors as large as 15 cm have been reported. Intracardiac tumors arise from the atrial or ventricular wall as nodular masses protruding into the cardiac chambers. Cardiac and pericardial teratomas are easily detected in the fetus and neonate by two-dimensional echocardiography as heterogeneous and encapsulated cystic masses. Histologically, cardiac teratomas contain multiple immature elements including epithelium, neuroglial tissue, thyroid, pancreas, smooth and skeletal muscle, cartilage and bone. [from
HPO]