Neuroectodermal and neuroendocrine tumors principally seen in children.

Neuroectodermal tumors comprise a large proportion of childhood neoplasms. Neuroblastic tumors, including neuroblastoma, ganglioneuroblastoma, and ganglioneuroma, are the most frequent extracranial solid cancers of childhood, occurring primarily in infants and toddlers. Primitive neuroectodermal tumors, including Ewing sarcoma and peripheral neuroepitheliomas, occur most frequently in older children and adolescents, and as pediatric sarcomas are second in frequency only to rhabdomyosarcomas. Rarer neuroectodermal tumors include desmoplastic small cell tumors, esthesioneuroblastomas, and melanotic neuroectodermal tumors, the first two entities occurring as rather site-specific lesions in the abdomen and nose, respectively. Diagnosis can be difficult due to the undifferentiated nature of many of these cancers, but ancillary studies, including electron microscopy, immunohistochemistry, cytogenetics, and molecular genetics, enhance their recognition. The molecular nature of childhood neuroectodermal tumors is as diverse as their histology, ranging from the fusion genes characterizing the Ewing sarcoma family of tumors to the proto-oncogene amplification seen in aggressive neuroblastomas.