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Medulloblastoma definition: A malignant neoplasm that may be classified either as a glioma or as a primitive neuroectodermal tumor of childhood (see NEUROECTODERMAL TUMOR, PRIMITIVE). The tumor occurs most frequently in the first decade of life with the most typical location being the cerebellar vermis. Histologic features include a high degree of cellularity, frequent mitotic figures, and a tendency for the cells to organize into sheets or form rosettes. Medulloblastoma have a high propensity to spread throughout the craniospinal intradural axis. (From DeVita et al., Cancer: Principles and Practice of Oncology, 5th ed, pp2060-1)
medulloblastoma definition: malignant cerebellar neoplasm composed of undifferentiated neuroepithelial cells that may be classified either as a glioma or as a primitive neuroectodermal tumor of childhood; tumor occurs most frequently in the first decade of life with the most typical location being the cerebellar vermis.
medulloblastoma definition: (MED-yoo-lo-blas-TOE-ma) A malignant brain tumor that begins in the lower part of the brain and that can spread to the spine or to other parts of the body. Medulloblastomas are a type of primitive neuroectodermal tumor (PNET).
Medulloblastoma definition: A malignant, invasive embryonal neoplasm arising from the cerebellum. It occurs predominantly in children and has the tendency to metastasize via the cerebrospinal fluid pathways. Signs and symptoms include truncal ataxia, disturbed gait, lethargy, headache, and vomiting. There are four histologic variants: classic medulloblastoma, desmoplastic medulloblastoma, large cell medulloblastoma, and medulloblastoma with extensive nodularity and advanced neuronal differentiation.
Childhood Medulloblastoma definition: A medulloblastoma occurring in children.
Adult Medulloblastoma definition: A medulloblastoma occurring in adults.
Recurrent Childhood Medulloblastoma definition: The reemergence of childhood medulloblastoma after a period of remission.
Desmoplastic Medulloblastoma definition: A medulloblastoma characterized by the presence of nodular, collagenous areas which do not contain reticulin, surrounded by hypercellular areas which contain an intercellular reticulin fiber network.
Large Cell Medulloblastoma definition: A medulloblastoma composed of large cells with prominent nucleoli and a larger amount of cytoplasm in contrast with the cells of the classic medulloblastoma.
Melanotic Medulloblastoma definition: A rare malignant embryonal neoplasm characterized by the presence of small cells which resemble the cells of classic medulloblastoma and a minor population of melanin-forming neuroepithelial cells. It usually has an unfavorable clinical course.
Adult Brain Medulloblastoma definition: A medulloblastoma arising from the brain, occurring in adults.
Cerebellar Vermis Medulloblastoma definition: A medulloblastoma arising from the vermis of the cerebellum.
Familial Adenomatous Polyposis Associated Medulloblastoma definition: A medulloblastoma developing in patients with familiar adenomatous polyposis syndrome. It is observed in patients with Turcot syndrome, type 2.
Medulloblastoma with Leptomeningeal Spread definition: A medulloblastoma which has spread from its original site to the leptomeninges surrounding the brain and spinal cord.
Nevoid Basal Cell Carcinoma Syndrome Associated Medulloblastoma definition: A medulloblastoma developing in patients with multiple basal cell carcinomas. It is observed in patients with nevoid basal cell carcinoma syndrome and it is associated with PTCH gene inactivation.
Medulloblastoma with Extensive Nodularity and Advanced Neuronal Differentiation definition: A medulloblastoma characterized by nodularity and neuronal differentiation. Ganglion cells may be present.
Recurrent Medulloblastoma definition: The reemergence of medulloblastoma after a period of remission.
Region 17p13 Allelic Loss Associated Medulloblastoma definition: A medulloblastoma characterized by the loss of one of the p13 regions of chromosome 17. Loss of genetic material of chromosome arm 17p is the most common molecular genetic abnormality found in medulloblastomas.
Cerebellar Liponeurocytoma definition: A rare, WHO grade I or II cerebellar neoplasm which shows advanced neuronal/neurocytic and focal lipomatous differentiation. It occurs in adults, has a low proliferative potential and has a favorable prognosis. (Adapted from WHO)
Classic Medulloblastoma definition: A medulloblastoma composed of malignant cells with hyperchromatic nucleus and scanty cytoplasm. Homer Wright rosettes may be present.