EPENDYMOBLASTOMA

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Contents

Definition

Ependymoblastoma is a highly malignant embryonal tumor of infancy and young childhood characterized by neuroectodermal elements organized in distinctive multilayered rosettes. Ependymoblastoma corresponds to WHO Grade IV.

Epidemiology

Ependymoblastoma is a rare tumor that occurs in infants and young children in the first two years of life. Both sexes are affected equally.

Localization

Ependymoblastomas are large lesions that occur in the supratentorial compartment. A physical connection to the ventricular system is typical.

Clinical presentation

Patients present with signs and symptoms of raised intracranial pressure and hydrocephalus. Focal neurological signs may be present in older children.

Imaging

On MRI, ependymoblastomas are large heterogeneously enhancing lesion with associated brain edema and mass effect.

Macroscopy

Ependymoblastomas are well-circumscribed lesions, with a distinct margin between tumor and normal brain, though focal microscopic extension and leptomeningeal invasion are common.

Histopathology

Ependymoblastoma is a primitive neuroectodermal tumor with tumor cell arranged in multilayered rosettes consisting of an outer rim of tumor cells merging with the surrounding undifferentiated neuroectodermal cells. The tumor cells are immunopositive for S100, vimentin, cytokeratin and GFAP, and show high mitotic activity.

Molecular genetics

Cytogenetic studies of ependymoblastoma have demonstrated gains of chromosome 2 as well as losses of chromosomes 6q and 13q.

Prognosis

Mean survival time following surgical resection is 6-12 months. Tumor recurrence and craniospinal dissemination are expected.

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