Although the symptoms had become troublesome only recently, their underlying cause had been present for all of our middle-aged patient's life.
Mr. W, a 50-year-old Caucasian, presented to the emergency department (ED) complaining of worsening chest palpitations for the past four days. The palpitations worsened on exertion and were relieved only with rest. He denied chest pain, dyspnea, or other symptoms.
In the ED, his vital signs were BP 165/92 mm Hg, heart rate 44 beats per minute, respiratory rate 16 breaths per minute, and temperature 99.1°F. Physical examination was unremarkable. In 1991 Mr. W, who had a history of IV drug use, tested positive for HIV; at the time of testing, his CD4 count was 852/µL. Until two months before presenting to the ED, he was in his usual state of health.
An ECG revealed sinus bradycardia 60 beats per minute, and a chest x-ray showed abnormal prominence of the right heart border. On echocardiography, chamber sizes and wall motion were normal; the ejection fraction was 65% with pulmonary arterial pressure 25 mm Hg. A chest CT with IV contrast (above, left) found an anterior mediastinal mass measuring 6.9 × 4.6 × 5.8 cm. The mass contained central regions of intermediate attenuation, septations, and peripheral calcifications and was having some effect on the superior vena cava and right side of the heart.
A WELL-ENCAPSULATED MASS
1 Sternotomy showed an intrapericardial mass, which turned out to be cystic and well-encapsulated. It was attached to the greater curvature of the ascending aorta and measured 7 × 5 × 4 cm. Pathology noted that the 134-g specimen contained multilocular cystic spaces with white and yellow “cheeselike” and “tan-brown muddy” material. The wall contained granular calcified lesions associated with areas of hemorrhage. The final diagnosis was mature cystic teratoma, which had likely started growing again after being quiescent. Mr. W did well and was discharged to outpatient follow-up.
SLOW, ASYMPTOMATIC GROWTH
2 Teratomas are neoplasms composed of multiple tissue elements derived from the three primitive embryonic layers. Peak incidence is in the second and third decades of life without predilection for either sex. Mature cystic teratomas of the mediastinum are generally benign, although they have malignant potential. Because these tumors often grow slowly, they are more likely to be diagnosed incidentally while they are still asymptomatic.
Symptoms, when present, are related to mechanical effects and include chest pain, cough, dyspnea, bronchial obstruction with post-obstructive pneumonia, and, rarely, palpitations. Erosion into an adjacent bronchus has led to expectoration of hair (trichoptysis) or sebaceous debris, findings pathognomonic of benign teratoma. Erosion into the pericardium, adjacent vascular structures, or through the skin to form a draining fistula is a rare but serious complication. Anterior mediastinal teratoma causing cardiac tamponade is an uncommon entity.1,2 There have also been a few documented cases of mediastinal teratomas producing significant amounts of hormones (insulin, glucagon, and somatostatin).
Chest radiography typically shows an anterior mediastinal mass, with calcification seen in 25% of benign teratomas. Well-formed teeth and bone seen on plain film are very suggestive of the diagnosis. CT and MRI are helpful in localizing lesions and determining the spatial relationships to surrounding structures. Imaging can also characterize intralesional densities suggestive of fat, sebaceous material, or cystic elements.2,3
AN UNCOMMON LOCATION
3 Germ cell tumors are thought to originate from primordial cells that fail to complete the migration from the urogenital ridge and come to rest, instead, in the mediastinum. Mediastinal masses are generally located anteriorly. The anterior mediastinal compartment (also known as the anterosuperior compartment) lies in front of the pericardium and houses lymphatic tissue, the thymus, the extrapericardial aorta and its branches, and the great veins.4
Tumors located in this area tend to be malignant. Germ cell tumors are the third most common tumors (17%) seen here, the others being thymomas (32%) and lymphomas (23%). The classifications of germ cell tumors are teratomas, teratocarcinomas, seminomas, embryonal cell carcinomas, choriocarcinomas, and endodermal cell (yolk sac) tumors.4
The true incidence of intrapericardial teratoma is not known, since some earlier authors included intrapericardial bronchogenic cysts in this category. Nonetheless, approximately 55 cases of intrapericardial teratomas have been reported in the literature up to the year 2001. The most frequent site of teratomas is the sacrococcygeal area, followed by the mediastinum and the gonads.4
The first malignant intracardiac teratoma was reported in 1973.5 It consisted of various mature and immature elements and partially filled the right ventricle. Sarcomatous tissue consistent with leiomyosarcoma, stratified keratinizing squamous epithelium, and poorly differentiated small epithelial cells comprised the malignant components. Intracardiac teratomas have the propensity to originate from the interatrial and interventricular septum and grow into the right chambers. Metastasis, though rare, can be to the lungs, brain, and bones.5
Among the solid components found in teratomas are well-differentiated elements of bone, cartlilage, teeth, muscle, connective tissue, fibrous and lymphoid tissue, nerve, thymus, mucous and salivary glands, lung, liver, and pancreas. When more than 50% of the tumor elements are well-differentiated, the tumor is considered to be mature. The presence of embryonic or primitive tissues in malignant tumors distinguishes them from benign tumors.5
THE ONLY TREATMENT OPTION
4 Mature teratomas are relatively insensitive to both chemotherapy and radiation. Surgical excision is usually curative. Subtotal resection with relief of compressive symptoms is performed if benign teratomas cannot be excised completely without endangering surrounding vital structures. Resection generally is through a median sternotomy or posterolateral thoracotomy, although thoracoscopic resection is occasionally possible.
Most intrapericardial tumors are observed in infancy as large masses attached by a fibrous pedicle on the right, anterior side of the heart. Excision is warranted because they carry
a risk for malignant transformation, may lead to compression and arrhythmias due to their proximity to surrounding vital structures, and could become infected. Since the tumor is pedunculated, surgical excision is not usually problematic. However, the blood supply is derived from the adventitial vessels of the aorta, so dissection carries a small risk of massive aortic hemorrhage.
Dr. Cohen is chief of cardiology, Department of Medicine, Woodhull Hospital, Brooklyn, N.Y. where Dr. Mena, Dr. Gomez, and Dr. Bido are residents and Dr. Mejia is chief of medicine.
References
1. Lewis BD, Hurt RD, Payne WS, et al. Benign teratomas of the mediastinum. J Thorac Cardiovasc Surg. 1983;86:727-731.
2. Adebonojo SA, Nicola ML. Teratoid tumors of the mediastinum. Am Surg. 1976;42:361-365.
3. Gunes S, Varon J, Walsh G. Mediastinal teratoma presenting as massive hemoptysis in an adult. J Emerg Med. 1997;15:313-316.
4. Feigin DS, Fenoglio JJ, McAllister HA, Madewell JE. Pericardial cysts. A radiologic-pathologic correlation and review. Radiology. 1977;125:15-20.
5. Cabanas VY, Moore WM 3rd. Malignant teratoma of the heart. Arch Pathol. 1973;96:399-402.