Supratentorial primitive neuroectodermal tumor
Supratentorial primitive neuroectodermal tumor(PNET or SPNET) (WHO grade IV) is an embryonal tumor in the cerebrum or suprasellar region that is composed of undifferentiated or poorly differentiated neuroepithelial cells, which have the capacity for differentiation along neuronal, astrocytic, ependymal, muscular, or melanocytic lines (Rorke et al. 2000).
This is a rare tumor that occurs in children (mean age, 5.5 years); a precise incidence has not been determined.
Imaging and Location
On MR imaging all PNETs were found to be either hypointense or isointense to normal white matter on T1-weighted images. In the study by Chawla et al. (2007), 10 of the 12 tumors were either isointense or hypointense on T2-weighted images, and 11 were isointense on FLAIR images. Patients with SPNETs had large, vascular, and hemorrhagic tumors.
On DWI, all PNETs were hyperintense and had restricted apparent diffusion coefficient. MRS (two patients with medulloblastoma and one with a SPNET), showed elevated choline, decreased N-acetyl aspartate, and a small taurine peak in all three patients.
Intraspinal tumor dissemination, visible as uniform or nodular enhancement coating the conus medullaris, was detected in 6 of 12 patients, 2 of whom also had intracranial dissemination.
Synonyms include cerebral medulloblastoma (see above), cerebral neuroblastoma, cerebral ganglioneuroblastoma, blue tumor, and primitive neuroectodermal tumor.
- M.F. Reiser, W. Semmler, H. Hricak (Eds.) "Magnetic Resonance Tomography", Springer 2008