الملخص

"A teratoma is a germ cell tumor composed of tissue derived from two or three germ layers-ectoderm, mesoderm, and endoderm". Teratomas are mostly found in children & young adults & usually originated in gonads & midline tissues. They have also been reported in extragonadal sites, such as retroperitoneum, sacrococcygeal region & mediastinum. Mediastinal teratomas are relatively rare comprising 8-13% of all tumors in mediastinum and 1- l0% of germ cell tumors developing in mediastinum. We are presenting a case of 39 years old male who presented with progressive exertional dyspnea, orthopnea with frequent attacks of cough for 3years and feeling of pulsatile mass in left upper parasternal area in the last 4 months. Chest x-ray showed superior mediastinal shadow projecting to left upper chest zone and deviating the trachea to the right side of chest, differential diagnosis was aneurysm of aortic arch. Computed tomography (CT) scan of chest and CT angiography done and revealed a superior mediastinal mass of heterogeneous opacity containing fluid, soft tissue, bones and calcification encroaching the right pulmonary artery and compressing and deviating the trachea to the right. Complete surgical removal done through left thoracotomy, Final diagnosis of a mature cystic teratoma was given on histopathology. This case is being presented here because mediastinum is a rare site for teratoma and superior mediastinum was not reported as a site for teratoma from review of literature.