Germ Cell Tumors of the Mediastinum / Thymus
Definition
- Neoplasms exhibiting features of gonadal germ cell neoplasms arising in the mediastinum
Diagnostic Criteria
- All types of gonadal germ cell tumors (GCT) may be seen in the mediastinum
- Mature teratoma is by far the most common type
- Occurs roughly equally in males and females
- Immature teratoma and all other types of GCT occur virtually only in males
- Mature teratoma is by far the most common type
- Histologic patterns are essentially the same as in their gonadal counterparts
- Seminoma may be obscured by inflammatory response, thymic epithelial hyperplasia and cyst formation
- Hematologic malignancy may rarely be associated with mediastinal GCT
- Most common types are:
- Acute myelogenous leukemia
- Acute megakaryocytic leukemia
- Rare cases reported as malignant histiocytosis
- Probably really anaplastic large cell lymphoma
- Most frequently associated with yolk sac tumor
- May be synchronous, appears not to be related to therapy
- Most common types are:
- Somatic malignancy may rarely be associated with mediastinal GCT
- Most common types:
- Embryonal rhabdomyosarcoma
- Angiosarcoma
- Myxoid liposarcoma
- May occur in both males and females
- Most common types:
- Almost all mediastinal GCT directly involve or are adjacent to the thymus
- Metastasis from a gonadal primary must be ruled out
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
