Germ cell, mesenchymal, and thymic tumors of the mediastinum.

Germ cell, mesenchymal, and thymic tumors of the mediastinum are an uncommon and heterogeneous group of neoplasms. Together they account for less than 25% of mediastinal tumors in childhood. The majority of these tumors are found in the anterior and superior mediastinum, but germ cell tumors and mesenchymal tumors may be located in all compartments. They share a broad range of histological subtypes and clinical behavior, tendency to be large in size, and a requirement for complete surgical excision as the major requirement for successful therapy.