1. Abstract Central neurocytoma (CN) is a benign brain tumor of intraventricular site; According to the World Health Organization (WHO) 2016, it is categorized as grade II. We report a series of 10 cases that were diagnosed with CN by immunhistochemistry of surgical specimens at our hospital. The Average age of our cases was 22 years old; and the male: female ratio was 7:3; Presenting symptoms were related to intracranial hypertension; the typical appearance of a CN was observed in all of the masses; heterogeneous signal with enhancement after injection of gadolinium; the lesions were located in the lateral ventricle. All our patients underwent two surgeries: first the placement of a ventriculo-peritoneal bypass valve followed by surgical removal of the tumor; the postoperative follow-up was favorable and the postoperative cerebral MRI was satisfactory. Surgical resection is the treatment of choice for intraventricular neurocytomas, with a generally favorable postoperative prognosis without tumor residue or recurrence; however, the approach has to be tailored specifically to each case.
Keywords: Central neurocytoma; Intraventricular; Immunhistochemistry.
2. Introduction Central neurocytoma (CN) is a benign brain tumor of intraventricular site; According to the World Health Organization (WHO) 2016, it is categorized as grade II [1]. Extra ventricular neurocytoma location is exceptionally rare [2,3]. It is rare, accounting for 0.1 to 0.5% of central nervous system tumors, and 10% of intraventricular tumors. It most often affects young adults; The main differential diagnosis is with intraventricular ependymomas and oligodendrogliomas, and CN mimic them histologically; The diagnosis of CN requires evidence of neuronal differentiation, demonstrated by electron microscopy or by positive immunohistochemical (IHC) staining for synaptophysin or other markers. MRI is the exam of choice for making a diagnosis and Its prognosis is generally favorable after adequate surgical removal, although some patients with recurrence and cerebrospinal dissemination have been reported [4,5].
3. Materiel and Methods We report a series of 10 cases that were diagnosed with CN by immunhistochemistry of surgical specimens at our hospital. These cases were retrospectively analyzed with reference to their clinical records, neuroradiological findings, histopathological results, and methods of management. Clinical and radiological follow-up was available for our patients and clinical outcomes were recorded.
4. Result4. Result The Average age of our cases was 22 years old; and the male: female ratio was 7:3; the average diagnostic time was 1.5 years; Presenting symptoms were related to intracranial hypertension; headache, blurred vision and one patient had no symptoms. The typical appearance of a CN was observed in all of the masses; heterogeneous signal with enhancement after injection of gadolinium; the lesions were located in the lateral ventricle (body of the right lateral ventricle) (Fig 01). All our patients underwent two surgeries: first the placement of a ventriculo-peritoneal bypass valve followed by surgical removal of the tumor; the postoperative follow-up was favorable and the postoperative cerebral MRI was satisfactory. We used three Approaches: 05 patients beneficiated from trans-frontal trans-ventricular approach; 03 trans-parietal trans-ventricular approach and 02 anterior trans-callosal approach.
5. Discussion Central neurocytoma is a benign tumor of the central nervous system of the intraventricular site; that originate from bi-potential progenitor cells in the periventricular matrix, Reports showed proofs for both glial and neuronal differentiation in many tumors [1, 6, 7]. It was first described in 1982 by Hasboun et Al, as a well-differentiated tumor of neuronal origin [3] and it is now classified as a grade II central nervous system tumor according to the World Health Organization classification system [1)] CN represents 0.1 to 0.5% of intracerebral tumors and 10% of intraventricular tumors [8,9,10]. It occurs most commonly in young adults in their thirties show a slight male predominance [11,12]; A Surveillance Epidemiology and End Results (SEER) data report of 229 CNs were more often female (53%) versus male (44%) (13). In contrast, Choudhari et al., in an extensive multidisciplinary review of published series found no gender predilection [14]. In our observations, the average age was 18 years with a sex ratio equals to 1 (Figure 1). Patients frequently present with symptoms of intracranial hypertension which remains the most common reason for consultation; intense headaches resisting the usual treatment, jet vomiting and papillary edema in the fundus; these symptoms are attributed to increased intracranial pressure secondary to obstructive hydrocephalus. We can also see visual disturbances, seizures, memory disorders as well as walking disorders; our data support these findings, since the majority of our patients complained of headaches (6,15). CN can also manifest itself by spontaneous intraventricular hemorrhage, neurological deficit, or even hormonal changes linked to the impairment of 3rd ventricle. The most common site of CN is the septum pellucidum or in the walls of the lateral ventricles and have a major intraventricular component, similar to most of our cases [11,16,17]. in 25% of the cases it extend into the 3rd ventricle towards Monro's hole, and 13% of the time it reaches both lateral ventricles, Only 3% sit exclusively in the 3rd ventricle, but the extension towards the 4th ventricle remains an extremely rare possibility. Extraventricular extension is possible and indicates a malignant transformation (cerebral hemispheres, cerebellum, spinal cord) [18]. CT scans of CN typically demonstrate an iso-intense or slightly hyperintense intraventricular mass with intratumoral calcifications which gives the gritty feel experienced by surgeons; and cystic areas within the lateral ventricles near the foramen of Monro; with mild to moderate enhancement after gadolinium. The septum pellucidum is usually not clearly visible as the tumor is centered on the midline and results in hydrocephalus (29,20). A uni or bilateral hydrocephalus can be observed, as was the case in our cases. Brain MRI remains the exam of choice ; typical CN MRI images are striking, an expansive process taking place in the lateral ventricle, with or without third ventricle extension, attachment to the septum pellucidum, and heterogeneous isointensity to hypointensity on T1-weighted and hyperintensity on T2-weighted sequences [21]. (The soft portion is hyperintense in T1 and T2 sequences, while cystic formations are hypointense in T1 and hyperintense in T2; T1 and T2 weighted hypointense areas may correspond to calcifications, hemorrhage or tumor neovasculisations). In our reported observations, the appearance is typical of a central neurocytoma by its location entirely intraventricular and the presence of the three components, solid tissue, cystic and calcifications. Extraventricular extension is possible and results in hypointense images in T1 sequences and a hyperintense signal in T2 sequences overflowing on the periventricular region indicating a malignant transformation. This extension was not observed in our cases.
6. Conclusion Central neurocytoma is a very rare benign intraventricular tumor. They still enigmatic in many terms: origin, histopathological diagnosis and adjuvant therapies needed. They usually occur in young adult and brain MRI makes it possible to make a precise lesion assessment and follow up. The diagnosis is histological, and the prognosis is often favorable after surgical treatment.
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Kamel Bouaita. Intraventricular Neurocytoma a Series of 10 Cases and Review of Literature. Annals of Clinical and Medical Case Reports 2021