Abstract
We describe the clinicopathological features of the central nervous system （CNS） embryonal tumors mainly Atypical Teratoid / Rhabdoid Tumors （AT/RTs）, Medulloblastomas （MB） and primitive neuroectodermal tumors （PNETs）.The subtypes of MB are included such as desmoplastic/nodular MB, MB with extensive nodularity, anaplastic MB, and large cell MB. Definition of MB is a malignant invasive embryonal tumor of the cerebellum with preferential manifestation in children, predominantly neuronal differentiation, and an inherent tendency to metastasize via CSF pathways. Recent prognosis of the patients with MB has been improved by advanced chemotherapy and radiotherapy. PNET is a heterogeneous group of tumors occurring predominantly in children and adolescents. They may arise in the cerebral hemispheres, brain stem, or spinal cord, and are composed of undifferentiated or poorly differentiated neuroepithelial cells which may display divergent differentiation along neuronal, astorocytic and ependymal line. CNS/supratentorial PNET is an embryonal tumor composed of undifferentiated or poorly differentiated neuroepithelial cells. Tumors with only neuronal differentiation are termed cerebral neuroblastomas or, if ganglion cells are also present, cerebral ganglionneuroblastomas.Recent prognosis of the patients with PNET has been also improved by advanced chemotherapy and radiotherapy like MB.AT/RT is defined as a highly malignant CNS tumor predominantly manifesting in young children, typically containing rhabdoid cells, often with primitive neuroectodermal cells and with divergent differentiation along epithelial, mesenchymal, neuronal or glial lines; associated with inactivation of the INI1/hSNF5 gene in virtually all cases. As the tumor entity is new and extremely malignant tumor, prognosis of the patients with AT/RT is still poor.
