- Primitive neuroectodermal tumor
Primitive neuroectodermal tumor Classification and external resources ICD-O: M9473/3 DiseasesDB 31470 eMedicine ped/2589 neuro/326 MeSH D018242
Primitive neuroectodermal tumor (PNET) is a neural crest tumor. It is a rare tumor, usually occurring in children and young adults under 25 years of age. After successful chemo- or(and) radio- therapy the 5 year survival rate is only 7,6-8% .
It gets its name because the majority of the cells in the tumor are derived from neuroectoderm, but have not developed and differentiated in the way a normal neuron would, and so the cells appear "primitive".
PNET belongs to the Ewing family of tumors.
It is classified into two types, based on location in the body: peripheral PNET and CNS PNET.
The peripheral PNET (pPNET) is now thought to be virtually identical to Ewing sarcoma:
"Current evidence indicates that both Ewing's sarcoma and PNET have a similar neural phenotype and, because they share an identical chromosome translocation, they should be viewed as the same tumor, differing only in their degree of neural differentiation. Tumors that demonstrate neural differentiation by light microscopy, immunohistochemistry, or electron microscopy have been traditionally labeled PNETs, and those that are undifferentiated by these analyses have been diagnosed as Ewing's sarcoma."
PNET of the CNS
PNET of the CNS generally refer to supratentorial PNETs.
- In the past medulloblastomas were considered PNETs, however they are genetically, transcriptionally and clinically distinct. As such "infratentorial" PNETs are now referred to as medulloblastoma.
- Pineoblastomas are embryonal tumours originating in the Pineal gland, and are likely distinct from supratentorial PNETs.
Patients diagnosed with a medulloblastoma or PNET are 50 times more likely to die than a matched member of the general population. The most recent population-based (Surveillance, Epidemiology and End-results Database) 5-year relative survival estimates are 64% in children (1-9 years) and 35% in adults (20+ years). 
Using gene transfer of SV40 large T-antigen in neuronal precursor cells of rats, a brain tumor model was established. The PNETs were histologically indistinguishable from the human counterparts and have been used to identify new genes involved in human brain tumor carcinogenesis. The model was used to confirm p53 as one of the genes involved in human medulloblastomas, but since only about 10% of the human tumors showed mutations in that gene, the model can be used to identify the other binding partners of SV40 Large T- antigen, other than p53.
- ^ "primitive neuroectodermal tumor" at Dorland's Medical Dictionary
- ^ 
- ^ Kumar, Vinay; Fausto, Nelso; Abbas, Abul (2004) Robbins & Cotran Pathologic Basis of Disease (7th ed.). Saunders. Page 1301. ISBN 0721601871.
- ^ Smoll NR "Relative Survival of Medulloblastomas and PNETs in children, adolescents and adults" Cancer (in press)
- ^ Eibl RH, Kleihues P, Jat PS, Wiestler OD (March 1994). "A model for primitive neuroectodermal tumors in transgenic neural transplants harboring the SV40 large T antigen". Am. J. Pathol. 144 (3): 556–64. PMC 1887088. PMID 8129041. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1887088.
- ^ Ohgaki H, Eibl RH, Wiestler OD, Yasargil MG, Newcomb EW, Kleihues P (November 1991). "p53 mutations in nonastrocytic human brain tumors". Cancer Res. 51 (22): 6202–5. PMID 1933879. http://cancerres.aacrjournals.org/cgi/pmidlookup?view=long&pmid=1933879.
Nervous tissue tumors/NS neoplasm/Neuroectodermal tumor (ICD-O 9350–9589) (C70–C72, D32–D33, 191–192/225) Endocrine/
(9380–9539)Ependymoma · SubependymomaMultiple/unknownMature
(9540–9579)note: not all brain tumors are of nervous tissue, and not all nervous tissue tumors are in the brain (see brain metastases)
Connective tissue neoplasm: Osseous and Chondromatous tumors (ICD-O 9180–9269) (C40–C41/D16, 170/213) DiaphysisPNET/Ewing family Metaphysis Epiphysis Other/ungrouped
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Look at other dictionaries:
primitive neuroectodermal tumor — (PNET) a heterogeneous group of neoplasms thought to derive from undifferentiated neuroglial cells of the neural crest. Some occur in the brain and some (the peripheral neuroectodermal tumors) elsewhere, such as on a limb, the pelvis, or the… … Medical dictionary
primitive neuroectodermal tumor — PNET. One of a group of cancers that develop from the same type of early cells, and share certain biochemical and genetic features. Some PNETs develop in the brain and central nervous system (CNS PNET), and others develop in sites outside of the… … English dictionary of cancer terms
central nervous system primitive neuroectodermal tumor — CNS PNET … English dictionary of cancer terms
peripheral primitive neuroectodermal tumor — A type of cancer that forms in bone or soft tissue. Also called pPNET and Ewing sarcoma … English dictionary of cancer terms
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Primitive neuroectodermal tumors — A type of brain tumor believed to originate in neural crest cells. Diagnosis is by biopsy. Treatment is by radiation and/or chemotherapy. Abbreviated PNET. See also Ewing’s sarcoma … Medical dictionary
peripheral neuroectodermal tumor — (PNET) a primitive neuroectodermal tumor occurring outside of the central nervous system, such as on a limb, the pelvis, or the chest wall; seen most often in adolescents and young adults, frequently with widespread metastases … Medical dictionary
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