Germ Cell Tumors

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Germ cell tumors are rare mediastinal lesions that are thought to originate from aberrant migration of germ cells to the thymus during embryogenesis. These tumors account for approximately 10–15 % of all mediastinal tumors and cysts. All types of germ cell tumors arising at other body sites (i.e., gonads, retroperitoneum, pituitary) have been described in the mediastinum. Teratomas, the most common type of germ cell tumor of the mediastinum, occur mostly in children or young adults. The vast majority of germ cell tumors originating from the mediastinum arise in the anterior compartment. Mediastinal germ cell tumors show a striking predilection for men. Most present with symptoms related to compression of surrounding structures. Malignant germ cell tumors of the mediastinum can secrete fetal oncoproteins, including alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG). Elevation of these proteins can be assessed easily by serology, aiding in the preoperative diagnosis. An important clinical association has been observed in patients with Klinefelter’s syndrome, who show an increased predisposition for the development of germ cell malignancy and hematologic abnormalities. An increased incidence of hematologic disorders such as acute leukemias, malignant histiocytosis, or systemic mastocytosis has also been observed in patients with mediastinal germ cell tumors.