Malignant mediastinal germ cell tumors
of various histologies were first described as a clinical entity approximately 50 years ago. Mediastinal
and other extragonadal germ cell tumors
were initially thought to represent isolated metastases
from an inapparent gonadal
Some investigators suggest that this distribution arises as a consequence of abnormal migration of germ cells during embryogenesis
. Others hypothesize a widespread distribution of germ cells to multiple sites during normal embryogenesis, with these cells conveying genetic information or providing regulatory functions at somatic sites.
Malignant germ cell tumors of the mediastinum are uncommon, representing only 3 to 10% of tumors originating in the mediastinum. They are much less common than germ cell tumors arising in the testes
, and account for only 1 to 5% of all germ cell neoplasms
Unlike benign germ cell tumors of the mediastinum, malignant mediastinal tumors are usually symptomatic at the time of diagnosis. Most mediastinal malignant tumors are large and cause symptoms by compressing or invading adjacent structures, including the lungs, pleura, pericardium, and chest wall.Seminomas
grow relatively slowly and can become very large before causing symptoms. Tumors 20 to 30 cm in diameter can exist with minimal symptomatology.
Evaluation and Staging
The diagnosis of a... Read More