Central nervous system primitive neuroectodermal tumor | |
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Primitive neuroectodermal tumor of the central nervous system in a 5-year-old |
A central nervous system primitive neuroectodermal tumor, often abbreviated as PNET, supratentorial PNET, or CNS-PNET,[1] is one of the 3 types of embryonal central nervous system tumors (medulloblastoma, atypical teratoid rhabdoid tumor, and PNET).[2] It is considered an embryonal tumor because it arises from cells partially differentiated or still undifferentiated from birth.[1] Those cells are usually neuroepithelial cells,[1][2][3] stem cells destined to turn into glia or neurons.[4] It can occur anywhere within the spinal cord and cerebrum and can have multiple sites of origins, with a high probability of metastasis through cerebrospinal fluid (CSF).[1][2]
PNET has five subtypes of tumors: neuroblastoma, ganglioneuroblastoma, medulloepithelioma, ependymoblastoma, and not otherwise specified PNET.[1] It is similar to medulloblastoma regarding histology but different regarding genetic factors and tumor site. It is a rare disease occurring mostly among children,[1][2] accounting for 1.9 to 7% of childhood brain tumors.[2] Symptoms involve emotional, visual, motor, and speech defects.[2] Magnetic resonance imaging (MRI) and computed tomography (CT) are used to diagnose PNETs.[2] Even though a universal treatment plan hasn't been stablished yet, common strategies involve chemotherapy and radiotherapy for individuals older than 3 years of age.[1][2] Their efficacy, however, is still controversial.[2] Surgery can be used to remove mass affected by tumorous cells.[2] The prognosis of the disease is more positive for adults than for children, who have a higher probability of having sequelae from the tumor.[1][2]
It is important to note that this classification term has been removed from the latest WHO classification of CNS tumors as of 2016. Instead PNETs are now included into the category of "Embryonal Tumors with Multilayered Rosettes" along with ependymoblastoma and embryonal tumor with abundant neuropil and true rosettes (ETANTR).[5]