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)