Genetic Markers of Mediastinal Tumors

Most adult mediastinal tumors are thymic in nature, and only more recently has there been scientific inquiry into the molecular biology and genetic alterations associated with these tumors. There is an increasing appreciation of specific genetic polymorphisms in myasthenia gravis and associated thymoma. In addition, thymic tumor progression is regulated by perturbations in expression of specific tumor suppressor genes and signal transduction pathways important in oncogenesis. This article highlights the known genetic and signaling pathway alterations important in the tumor biology of mediastinal tumors, with emphasis on thymic tumors. It also discusses the association of genetic markers with thymoma, thymic carcinoma, germ cell tumors, lymphoma, and neurogenic tumors. New gene-based techniques have enabled scientists to uncover differential gene expression patterns between subtypes of thymomas, correlate tumor marker expression with germ cell tumors, and determine a link between the NF-κB and JAK/STAT pathways with Hodgkin's and non-Hodgkin'slymphoma. Additionally, the use of genetic analysis has uncovered an important role for various tumor suppressor genes in the pathogenesis of paraganglioma and pheochromocytoma.