<unk>  (also known as "PNET") is a rare type of malignant tumor originating from neuroectoderm. Neuroectoderm is normally involved in the development of the nervous system. Apart from central nervous system (CNS),<unk> s can involve other tissues originating from the neuroectoderm such as muscles and bones. <unk>  was first discovered by James Ewing, an American pathologist, in 1921.  However, the term<unk> s was more commonly described in 1973 by Hart and Earle. In fact,<unk> s are members of the Ewing tumor family.<unk>  are classified into 3 subtypes. Histopathologically,<unk> s should be differentiated from other tumors causing small round blue cell tumors involving bone and soft tissue.<unk> s are more common among children. Clinical presentation of<unk> s is often non-specific and depend on the site of the tumor. Physical examination may be remarkable for papilledema, strabismus, nystagmus, imbalance, motor weakness, facial sensory loss, third, fourth, and sixth cranial nerve palsies, hemiplegia, hepatosplenomegaly, and adenopathy. On CT,  findings associated with the diagnosis of<unk> s, may include a large irregular mass with heterogeneous contrast enhancement. On MRI, findings of the<unk> s may include highly variable and can be hypo-intense to isointense, but usually, hypo-intense on T1-weighted images and high signal solid components on T2-weighted images. For the management of peripheral form of<unk> , systemic chemotherapy has been associated with a better prognosis and is generally recommended.
Primitive neuroectodermal tumor
Ameloblastoma
Dysembryoplastic neuroepithelial tumor
Neuroma
Endodermal sinus tumor
Malignant rhabdoid tumour
Malignant rhabdoid tumor
Pineoblastoma