ABSTRACT
Mature teratomas are the most common type of mediastinal germ cell tumors. They typically occur in young adults [15 to 35 years] and 95% of these teratomas occur in the anterior mediastinum. Herein, we report a case of a huge mediastinal teratoma in a 16-year-old boy who presented with a history of chest pain, cough, exertional dyspnea, and fever. Chest X-ray and spiral computed tomography [CT] revealed a bulky mass of 20 cm X 15 cm in the right side of the posterior mediastinum. The operative finding was a large cystic mass in the posterior mediastinum adherent to the neighbor organs. The cyst was filled with sebum, hair and calcified materials. The resected tumor was in the posterior mediastinum, although most of these tumors occur in the anterior mediastinum. To the best of our knowledge, this is the first documented report in Iran