A<unk>  is a<unk>  or tumor of the neuroectoderm. They are most commonly tumors in the central or peripheral nervous system. Tumors exhibiting<unk>  differentiation are classified into two main groups: * Group I tumors/neoplasms: neuroendocrine carcinomas. These show predominantly epithelial differentiation. They include pituitary adenoma and carcinoid tumor * Group II tumors/neoplasms: nonepithelial<unk> s. These are predominantly neural in origin. They include malignant melanoma, olfactory neuroblastoma and Ewing's sarcoma.
Neuroectodermal neoplasm
Extracranial germ cell tumor
Connective tissue neoplasm
Neuroendocrine tumor
Central nervous system primitive neuroectodermal tumor
Primitive neuroectodermal tumor
Malignant peripheral nerve sheath tumor
Dysembryoplastic neuroepithelial tumour