nounpl. -·mas, -·mata
a rare type of malignant tumor, found in some young children, that is formed from embryonic nerve cells
nounpl. neu·ro·blas·to·mas, or neu·ro·blas·to·ma·ta
A malignant tumor composed of neuroblasts, originating in the autonomic nervous system or the adrenal medulla and occurring chiefly in infants and young children.