yolk sac tumor of central nervous system
A malignant germ cell tumor of the central nervous system composed of primitive-appearing epithelial cells - putatively representing yolk sac endoderm - set in a loose, variably cellular, and often conspicuously myxoid matrix, resembling extra-embryonic mesoblast. Eosinophilic hyaline globules immunoreactive for AFP are a diagnostic feature. (WHO)