NCIt definition : A usually malignant neoplasm composed of primitive (immature) tissues that resemble
fetal tissues. Medulloblastoma, ependymoblastoma, pineoblastoma, and Wilms tumor are
representative embryonal neoplasms.;
Alternative definition : NCI-GLOSS: A mass of rapidly growing cells that begins in embryonic (fetal) tissue.
Embryonal tumors may be benign or malignant, and include neuroblastomas and Wilms
tumors.;