Twelve-Month BMI and Metabolic Changes After Roux-en-Y Gastric Bypass in Women with Severe Obesity.

Extraventricular neurocytoma (EVN) is an uncommon neuronal neoplasm classified by the World Health Organization (WHO) within the group of neuronal and glioneuronal tumors and is currently recognized as a central nervous system (CNS) WHO grade 2 neuronal neoplasm according to the 2021 WHO Classification of Central Nervous System Tumors []. Unlike central neurocytoma, which typically arises within the lateral ventricles near the foramen of Monro, EVN develops within the brain parenchyma without connection to the ventricular system and may occur in various supratentorial locations, particularly within the frontal and temporal lobes [,]. EVN is an exceptionally rare tumor, accounting for less than 0.5% of all primary central nervous system neoplasms, and predominantly affects young adults, although sporadic cases have been reported in older patients [,]. Clinical presentation depends largely on tumor location and commonly includes seizures, headache, and focal neurological deficits secondary to mass effect []. Preoperative diagnosis remains challenging because radiological findings are often nonspecific and may mimic high-grade intra-axial neoplasms. Features such as solid-cystic components, vasogenic edema, heterogeneous contrast enhancement, and midline shift may lead to an erroneous diagnosis of glioblastoma or other glial tumors []. Accurate distinction between EVN and high-grade gliomas is clinically important because these entities differ substantially in biological behavior, prognosis, and therapeutic management. Therefore, definitive diagnosis requires careful clinicoradiopathological correlation supported by immunohistochemical studies. Histologically, extraventricular neurocytomas are characterized by a proliferation of relatively uniform cells with round nuclei and finely granular chromatin embedded within a delicate vascular network. Synaptophysin positivity represents the most characteristic immunohistochemical finding, whereas focal GFAP expression may occasionally be observed in tumors exhibiting limited glial differentiation [,]. Maximal safe surgical resection remains the cornerstone of treatment, whereas adjuvant radiotherapy and, in selected cases, chemotherapy may be considered for patients with residual disease or other high-risk features [,].