Central Nervous System Primitive Neuroectodermal Tumors

Abstract

In 1910, James Homer Wright (of Homer Wright rosette fame) first separated the medulloblastoma from other CNS tumors. His concept was further refined by Percival Bailey, who defined a group of 29 tumors arising in the cerebellar vermis, primarily in children. Following the lead of the nineteenth century German pathology school, where tumors were named based on the concept of a cell of origin, Bailey named these tumors medulloblastomas. The cell of origin model then continued to be used in CNS tumor nomenclature, leading to the definition of a variety of “embryonal” tumors of the nervous system. This nomenclatural system is predicated on the assertion by the late Dr. Lucien Rubenstein that the central nervous system contains several unique types of neuroepithelial precursor cells in different locations which may undergo transformation giving rise to a variety of morphologically similar, but biologically distinct, CNS tumors (1). In 1973, Hart and Earle described a group of small round blue cell tumors of the central nervous system in children and introduced the diagnostic appellation “primitive neuroectodermal tumor” (PNET) (2). Dr. Lucy Rorke subsequently suggested that the term be broadened to include all primary CNS tumors composed of primitive neuroepithelial cells regardless of their location within the CNS. The codification of these previously disparate entities into a unique class of tumors is eloquently supported in her recent review (3)