Discussion :
According to the 2016 WHO CNS classification, CNS embryonal tumors (NOS) are embryonal tumors other than medulloblastoma, atypical teratoid or rhabdoid tumors, embryonal tumors with multilayered rosettes, medulloepithelioma, CNS neuroblastoma, and CNS ganglioneuroblastoma.(2)
CNS (NOS) is a category for the tumors previously called PNET, which cannot be classified under a genetic or molecular group. With the “NOS” designation (not otherwise specified), there is insufficient information for classification. Some of these tumors were previously named embryonal tumors with abundant neuropil and true rosettes. (3)
They are still considered a nosological entity with distinct biological behavior; they account for less than 0.5% of all brain tumors and predominantly affect children aged 0–14 (2). The incidence of adult CNS embryonal tumors is difficult to determine because of their rarity and lack of signature biomarkers.
In supratentorial locations, vomiting, seizures, and headaches are common. Hemiparesis is present if the tumor affects the cortical motor areas or the descending tracts. The presentation is also affected by age. Younger patients present with irritability, vomiting, and visual problems.(4)
In our case, our patient had symptoms of supratentorial presentations that included raised intracranial pressure and a focal neurologic deficit.
In most cases, ETNOS are hypercellular lesions composed of poorly differentiated cells exhibiting round to oval crowded nuclei with stippled chromatin, a high mitotic index, and frequent apoptotic bodies. Overall, neoplastic cells are positive for synaptophysin, GFAP, INI1, CD99, and vimentin and may also express NFP, EMA, p53, and CKM.(2)
The treatment consists of complete surgical excision; chemotherapy and radiation are necessary adjuncts. Generally, they have a poor prognosis. (5)
Chemotherapy varies with each protocol, but combining vincristine, cisplatinum, cyclophosphamide, and etoposide is common. Bevacizumab is used to block vascular endothelial growth factors. Intrathecal methotrexate and topotecan can be included in the treatment protocol.(4)