a tumor composed of immature undifferentiated cells

an abnormal growth (neoplasm) that arises from a group of cells that develop into a new organ, in this case the retina in normal development

a type of cancer that is caused by malignancies in precursor cells, often called

A tumour composed of very immature cells. See also: Medulloblastoma See also: Neuroblastoma

A tumor whose cells have embryonic characteristics, fast-growing and invasive.