Pediatr Surg Int (1995) 10: 188-189 © Springer-Verlag 1995 CASE REPORT S. Gupta • M. Bajpai • A. K. Gupta • D. K. Mitra Posterior mediastinal teratoma Accepted: 12 July 1994 Abstract Mediastinal teratomas usu- ally present in the anterior mediasti- num, almost always in contact with the thymus. However, rare cases have also been described in the pericardium and posterior mediastinum. We present one such case of a successfully treated posterior mediastinal teratoma. Key words Teratoma • Posterior mediastinum Introduction The mediastinum is the second most common site of teratomas after the gonads. Most of these tumors lie in the anterior mediastinum in close as- sociation with the thymus. However, teratomas have also been discovered in the posterior mediastinum: nine such cases have been described in the world literature. We describe the tenth pos- terior mediastinal teratoma. S. Gupta • M. Bajpai ( ~ ) • D. K. Mitra Department of Pediatric Surgery E - 52, AIIMS Campus, New Delhi - 110029, India A. K. Gupta Department of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi 110029, India Case report A 4-year-old boy presented with loss of appetite for 2 years and low-grade fever and dry, persistent cough for 2 months. There was no associated dyspnea or chest pain. The only positive physical sign was somewhat reduced air entry in the right infrascapular region. Chest radiographs demonstrated a posterior mediastinal tumor growing into the right hemithorax. Routine investigations, including a hemogram and urine examination, were within normal limits. Computed tomography of the chest revealed a mass in the posterior mediastinum extending into the chest wall on the right side (Fig. 1); the serum alpha- fetoprotein level was 360 ng/ml (normal 0- 20 ng/ml). A right thoracotomy was undertaken and an 8x8-cm, firm, lobular, well-encapsulated tumor arising in the posterior mediastinum, extending into the right hemithorax, and covered by the mediastinal pleura was ex- cised. There was a small area of dense adhe- sion to the vertebral bodies and ribs poster- iorly, from which the tumor was completely detached. The esophagus, aorta, vagus, and sympathetic chain were not adherent to the tumor. Histopathologic examination revealed a benign cystic teratoma. The patient made a rapid recovery and was discharged on the 6th postoperative day. The serum alpha-fetoprotein decreased to 0.6 ng/ml 2 months after surgery. He has been well for the last 18 months. Discussion The posterior mediastinum is the space posterior to the heart, bounded later- ally by the mediastinal pleura and posteriorly by the vertebral column. The contents include the esophagus, descending aorta, vagus, sympathetic nerves, and peripheral nerves. The Fig. I CT scan showing a large, right poste- rior mediastinal mass containing fat, calcified areas, and soft-tissue regions characteristic of teratoma tumors that most commonly occur in this region are enteric cysts and neu- rogenic tumors, including neuroblasto- ma [6]. Teratomas are tumors derived from totipotent cells that contain cells de- rived from at least two types of germ- cell layers. The mediastinum is the second most common site for a terato- ma after the gonads. Most are found in the anterior mediastinum, almost al- ways in direct contact with the thymus, with which they are believed to form. Abberant migration can lead to the presence of teratomas elsewhere in the chest. Other structures arising from the lower branchial arches have been associated with teratoma; terato- mas developing from the lower bran- chial arches may lie in the posterior mediastinum in direct relation to the aorta [3]. Hedblom first reported three posterior mediastinal teratomas in his extensive review of 185 cases [1]. These cases were repeatedly cited