Primitive neuroectodermal tumor
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Primitive neuroectodermal tumor (PNET) is a rare tumor, usually occurring in children under 10 years old. It is classified into two types, based on location in the body: peripheral PNET and CNS PNET.

PNET belongs to the Ewing family of tumors.

Peripheral 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." ^[1]

PNET of the CNS

PNET of the CNS are grossly divided into supratentorial PNET and infratentorial PNET, the latter being more common. ^[2]

An example of infratentorial PNET includes medulloblastoma, which occurs in the cerebellum.

An example of supratentorial PNET includes pinealoblastoma, which occurs in the pineal region.

Ependymoblastoma

Ependymoblastoma is a synonym for PNET^[3]

Model

Using gene transfer of SV40 large T-antigen in neuronal precursor cells of rats, a brain tumor model was established. The PNETs were histologically indistinguashabe from the human counterparts and have been used to identify new genes involved in human brain tumor carcinogenesis. ^[4]. 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. ^[5]

See also

• Ewing family of tumors
• Ependymoma

References

1. ^ Robbins Pathologic Basis of Disease, 7th edition
2. ^ Subrata Ghosh, MD, MBBS, MS, Primitive Neuroectodermal Tumors of the Central Nervous System, eMedicine 2007.
3. ^ Ependymoblastoma at US National Institutes of Health Office of Rare Diseases
4. ^ Eibl RH, Kleihues P, Jat PS, Wiestler OD (1994) A model for primitive neuroectodermal tumors in transgenic neural transplants harboring the SV40 large T antigen. Am J Pathol. 1994 Mar;144(3):556-64.
5. ^ Ohgaki H, Eibl RH, Wiestler OD, Yasargil MG, Newcomb EW, Kleihues P: p53 mutations in nonastrocytic human brain tumors. Cancer Res (1991) 51:6202-5

• DeVita V, Hellman S, Rosenberg S. Cancer: Principles and Practice of Oncology, 5th ed. Lippincott Williams and Wilkins (1997). p2059. ISBN 978-0397515738

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