There is now general acceptance that extragonadal germ cell tumors, particularly pineal and mediastinal sites, represent malignant transformation of germinal elements distributed to these sites without a gonadal primary focus. Some investigators suggest that this distribution arises as a consequence of abnormal migration of germ cells during embryogenesis. Others have suggested that there is widespread distribution of germ cells to liver, thymus, bone marrow, and brain during normal embryogenesis and that these cells may provide important regulatory functions at somatic sites or convey genetic hematologic or immunologic information. flovent inhaler
Incidence and Epidemiology: Collective reviews of adults and children with mediastinal tumors give an estimate of the incidence of mediastinal germ cell tumors. Mullen and Richardson tabulated results of 702 adults and 179 children with common anterior mediastinal tumors. In adults, thymic lesions were the most common tumors representing 47 percent of cases. Lymphoma was the second most common (23 percent) and germ cell tumor accounted for 15 percent of adult anterior mediastinal tumors. In children, the relative frequencies of lymphomas (45 percent) and germ cell tumors (24 percent) were increased due to the rarity of thymic lesions in this age group.
Blog invites submissions of review articles, reports on clinical techniques, case reports, conference summaries, and articles of opinion pertinent to the control of pain and anxiety in dentistry.