How I do it? Resection of left ventricular central neurocytoma via trans-sulcal approach.

BACKGROUND: The management of lateral ventricle tumors requires a balance between maximizing safe resection and preserving neurological function. METHOD: The authors present a successful case of a left lateral ventricular central neurocytoma resection. The trans-superior frontal sulcus approach was employed, providing a safe corridor while minimizing damage to the surrounding neuroanatomy. The use of an endoscope further facilitated the procedure, enabling the confirmation of complete tumor removal and the preservation of deep venous drainage and periventricular structures. CONCLUSION: This case highlights the utility of the trans-sulcal approach and the benefits of endoscopic assistance in the management of lateral ventricle tumors.

Machine learning-based multiparametric magnetic resonance imaging radiomics model for distinguishing central neurocytoma from glioma of lateral ventricle.

OBJECTIVES: To develop a machine learning-based radiomics model based on multiparametric magnetic resonance imaging (MRI) for preoperative discrimination between central neurocytomas (CNs) and gliomas of lateral ventricles. METHODS: A total of 132 patients from two medical centers were enrolled in this retrospective study. Patients from the first medical center were divided into a training cohort (n = 74) and an internal validation cohort (n = 30). Patients from the second medical center were used as the external validation cohort (n = 28). Features were extracted from contrast-enhanced T1-weighted and T2-weighted images. A support vector machine was used for radiomics model investigation. Performance was evaluated using the sensitivity, specificity, and the area under the receiver operating characteristic curve (AUC). The model's performance was also compared with those of three radiologists. RESULTS: The radiomics model achieved an AUC of 0.986 in the training cohort, 0.933 in the internal validation cohort, and 0.903 in the external validation cohort. In the three cohorts, the AUC values were 0.657, 0.786, and 0.708 for radiologist 1; 0.838, 0.799, and 0.790 for radiologist 2; and 0.827, 0.871, and 0.862 for radiologist 3. When assisted by the radiomics model, two radiologists improved their performance in the training cohort (p < 0.05) but not in the internal or external validation cohorts. CONCLUSIONS: The machine learning radiomics model based on multiparametric MRI showed better performance for distinguishing CNs from lateral ventricular gliomas than did experienced radiologists, and it showed the potential to improve radiologist performance. KEY POINTS: • The machine learning radiomics model shows excellent performance in distinguishing CNs from gliomas. • The radiomics model outweighs two experienced radiologists (area under the receiver operating characteristic curve, 0.90 vs 0.79 and 0.86, respectively). • The radiomics model has the potential to enhance radiologist performance.

Pediatric atypical extraventricular neurocytoma: Clinical features and survival outcomes.

BACKGROUND: Extraventricular neurocytoma (EVN) in children is an extremely rare encountered tumor. Little information is available about the treatment and prognosis of this rare disease in children. This study was undertaken to elucidate the clinical-radiological characteristics and treatment outcomes of pediatric patients with atypical EVN. METHODS: A retrospective review of patients' demographic features, treatment modalities, and outcomes in our institution from January 2011 to December 2019 was conducted. RESULTS: Seven consecutive children harboring atypical EVN in our center were included, with a male predominance (n = 5, 71.4%) and a mean age of 11.8 ± 4.9 years (range: 2-18 years). The lesions mainly involved the frontal (n = 4, 57.1%) and temporal lobes (n = 4, 57.1%). Gross total resection (GTR) was achieved in 6 patients (85.7%), and subtotal resection (STR) was achieved in the remaining patient (14.3%). All lesions demonstrated a high Ki-67 index (≧5%) and atypical features pathologically. Five patients (71.4%) received radiotherapy and/or chemotherapy after surgery. During follow-up, 5 patients (71.4%) experienced lesion progression, and 2 (14.3%) of them died. The median progression-free survival was 48 months. CONCLUSIONS: The prognosis of pediatric patients with atypical EVN was dismal after aggressive treatment. Most tumors progressed, and this progression was positively correlated with the Ki-67 index. Surgical excision is the main treatment modality for atypical EVN, and radiation/chemotherapy should also be introduced after surgery.

A rare case of atypical spinal neurocytoma with EGFR mutation in a 12-year-old boy.

Spinal neurocytoma (SN), although frequently reportedly as tumors of the central nervous system (CNS), are a distinct class of tumors, which can achieve a better prognosis following subtotal or gross total tumor resection. Nonetheless, even with the premise of successful treatment after tumor resection, poor prognosis after treatment due to the SN high proliferation index (typically known as atypical SN) have been reported. Over the past two decades, atypical SN was only reported in four pediatric cases, amidst the lingering controversy surrounding its postoperative adjuvant therapy. Thus, herein, we report a unique case of atypical SN with epidermal growth factor receptor (EGFR) amplification mutation in a 12-year-old boy. We, however, also highlighted the significance of radiotherapy and target therapy for patients with SN.

[Central neurocytomas: long-term treatment outcomes]. / Tsentral'nye neirotsitomy golovnogo mozga: otdalennye rezul'taty lecheniya.

Central neurocytoma is a rare benign brain tumor. These tumors may be giant and accompanied by compression of ventricular system and surrounding structures. Modern treatment of brain neurocytoma includes extended resection and restoration of normal CSF circulation. Surgical treatment does not often lead to total resection of these tumors. Redo resection was preferred in patients with tumor progression for a long time. In the last decade, various authors report stereotactic irradiation for continued tumor growth to ensure local growth control. This study was aimed at evaluation of postoperative outcomes in patients with brain neurocytomas, as well as treatment of tumor progression in long-term period. OBJECTIVE: To analyze recurrence-free survival in patients with brain neurocytomas, risk factors of recurrence-free survival, effectiveness of various treatments for tumor progression and delayed complications. MATERIAL AND METHODS: Long-term postoperative follow-up data of patients with brain neurocytomas are reported in the manuscript. We analyzed recurrence-free survival and risk factors of recurrence-free survival, treatment outcomes in patients with progression of brain neurocytomas, long-term complications and their prevention. RESULTS: Follow-up included 84 out of 115 patients with brain neurocytoma after surgical treatment in 2008-2017. Follow-up period ranged from 2 to 10 years (mean 6 years) after resection. Most patients had regression of neurological symptoms after surgery. Continued tumor growth within 12-96 months after surgery occurred in 26 (30.19%) out of 84 patients (19 cases after partial resection and 7 cases after total resection according to MRI data). Two-year recurrence-free survival was 94%, 5-year survival - 83%. Risk factors of continued tumor growth were resection quality and Ki-67 index. Redo resection was performed in 7 cases. Eleven patients underwent stereotactic irradiation for tumor progression. Indications for stereotactic irradiation of central neurocytoma are MR data on continued growth of lateral ventricle tumor without signs of ICH and CSF flow impairment. There were no cases of hemorrhage inside the residual tumor and CSF flow impairment in early postoperative period after redo resection. In all cases (n=11), stereotactic irradiation (mean follow-up 2.5 years) ensured satisfactory control of tumor growth with reduction of the neoplasm in 4 cases and no tumor growth in 7 cases. CONCLUSION: Resection of central neurocytoma ensures long-term recurrence-free period. The main causes of tumor recurrence are partial resection and high proliferative activity (Ki-67 index over 5%). Redo resection is advisable for tumor progression followed by CSF flow impairment. In case of continued growth of neurocytoma without signs of intracranial hypertension, stereotactic irradiation with various fractionation modes ensures effective and safe control of tumor growth.

Atypical extraventricular neurocytoma: A case report.

Atypical extraventricular neurocytoma (EVN) is a rare condition characterized by diffuse tumor cell hyperplasia, increased neovascularization, increased necrosis, and aggressive characteristics. A case of a 25-year old man who presented with atypical EVN in his left parietal - occipital flaps is reported. Magnetic resonance imaging (MRI) revealed a well-defined globular mass with heterogeneous signals in the left parietal lobe, and mild perilesional edema. After left parietal craniotomy and tumor excision, pathologic examination of the resected tissue revealed that the lesion was localized mainly in the white matter and imbued with tumor cells possessing round hyperchromatic nuclei with perinuclear halos and increased microvascular proliferation. The patient underwent radiotherapy at 21st postoperative day. Over the past 26 months, the patient has been regularly followed up, and so far no neurologic deficits have been observed. The latest MRI showed that the tumor bed was stable with slight peritumoral edema. The results of clinical, histopathological and immunohistochemical examinations indicate that atypical EVN is a rare neoplasm with unique radiographic and pathologic characteristics. It possesses more aggressive properties than typical EVN.

Application of diffusion-weighted imaging combined with apparent diffusion coefficient in differential diagnosis between central neurocytoma and ependymoma.

PURPOSE: Differential diagnosis between central neurocytoma and ependymoma is very important for making preoperative scheme. We explored the application of diffusion-weighted imaging (DWI) combined with apparent diffusion coefficient (ADC) in differential diagnosis between both. METHODS: The data of preoperative MR plain and contrast-enhanced scan, DWI and ADC values of neoplastic solid parts from 18 cases with central neurocytoma and 19 cases with lateral ventricular ependymoma, were retrospectively analyzed. Mann-Whitney test was used for the comparison of ADC values between central neurocytoma and ependymoma. The application of ADC values in the differential diagnosis between central neurocytoma and ependymoma was evaluated by ROC curve. RESULTS: The lesions showed hyperintensity-dominant mixed signal intensity on DWI and mean ADC was (0.65 ± 0.13) × 10-3 mm2/s in the 18 cases with central neurocytoma. In the 19 cases with ependymoma, 13 had hyperintensity-dominant mixed signal intensity on DWI and 6 had hypointensity-dominant mixed signal intensity on DWI, and mean ADC was (1.20 ± 0.23) × 10-3 mm2/s. The mean ADC value was significantly higher in the 19 cases with ependymoma than in the 18 cases with central neurocytoma (P < 0.001). The ADC of 0.87 × 10-3 mm2/s might be used as a threshold for differential diagnosis between central neurocytoma and ependymoma with an area under ROC curve of 0.98 ± 0.02 and a 95% confidence interval of 0.95-1.00. Its sensitivity, specificity, and accuracy were 90%, 100%, and 90%, respectively. CONCLUSION: There is a certain overlap in MRI imaging features between central neurocytoma and ependymoma. DWI combined with ADC value can improve peoperative diagnostic accuracy.

Imaging of extraventricular neurocytoma: a systematic literature review.

OBJECTIVE: Extraventricular neurocytoma (EVN) was firstly described in 1997. The current literature regarding imaging of EVN is limited to sporadic case reports and case series. EVN is still poorly considered in the differential diagnosis by neuroradiologists, thus diagnosis remains challenging. In this systematic review, we summarize and discuss computed tomography (CT) and magnetic resonance imaging (MRI) features of EVN cases described in the literature, in order to provide useful informations to neuroradiologists. To the best of our knowledge, this is the most extensive review about imaging of EVN. MATERIALS AND METHODS: A systematic review of the literature about imaging of EVN cases was done. Only case reports or case series in which imaging (CT and/or MRI) features were deeply described were included in the revision. Eligibility of studies was assessed independently by two authors and any disagreements resolved by discussion. RESULTS: Our search strategy revealed 224 articles. After implementation of inclusion and exclusion criteria, 35 studies were considered, and a total of 79 cases of EVN were analyzed. CONCLUSION: EVN has not specific characteristics, with a large and variable imaging spectrum. Usually it appears as a large tumor, with diameters superior to 40 mm, frequently involving the frontal lobe. CT density and MRI signal intensity typically mirror the presence of cystic, solid, or calcified elements; contrast enhancement is visible in 87% of cases. Today, diagnosis of EVN with only imaging techniques is not univocal; neuroradiologists can only suspect this type of lesion, while the definitive diagnosis remains histological.

Imaging characteristics of cerebral extraventricular neurocytoma with pathological correlation.

PURPOSE: Extraventricular neurocytoma (EVN) is an exceedingly rare tumor. In this study, we sought to characterize the imaging and pathological features of this uncommon tumor. METHODS: Retrospective review of 18 patients (9 male; 9 female) with pathologically confirmed EVN treated at a single center between 2005 and 2017. RESULTS: All patients had a solitary lesion. Sixteen lesions were found in hemispheres. The greatest tumor diameter ranged from 2.6 to 8 cm. The lesions were generally solid with cystic components; the solid portion appeared isodense or hyperdense on CT, isointense to hypointense on T1WI, and slightly hyperintense on T2WI. Heterogeneous hyperintensity interspersed with isointense or hypointense areas suggestive of hemorrhage, calcification or vascular flow voids were seen on T2WI. Heterogeneous enhancement was noted in 17 lesions; no enhancement was observed in one lesion. Cystic components were observed in 13 lesions; 9 of these showed characteristic perilesional cysts (9/13). Mild to moderate peritumoral edema (15/18), calcification (4/16), intratumoral hemorrhage (11/18) and vascular flow voids (10/16) were observed in some lesions. Pathologically, tumor cells showed round nucleus and fine neuropil matrix. Foci of calcification in the solid portion of the tumor were seen in five cases. Microcystic changes were observed in almost all cases. Some lesions exhibited positive staining for synaptophysin (Syn) (15/16) and neuronal nuclei (NeuN) (7/8). MIB-1 was determined for 10 patients; seven of these had an MIB-1 ≥ 3. These six patients experienced recurrence; four of them relapsed twice. CONCLUSIONS: EVNs occur as single intracranial solid mass with cystic components (especially peripherally located cysts); solid portion exhibits slight hyperintensity or heterogeneous signal intensity. Mild to moderate peritumoral edema, calcification, intratumoral hemorrhage and vascular flow voids were characteristic features of extraventricular neurocytoma. Positive staining for synaptophysin and neuronal nuclei confirmed the diagnosis. A combination of atypical pathologic features and atypical radiologic features should be considered for prognostic assessment.

Diagnostic value of six MRI features for central neurocytoma.

OBJECTIVES: To increase our understanding of the imaging features of central neurocytoma (CN) and improve the preoperative MRI diagnosis accuracy. METHODS: Preoperative MR images of 30 CNs and another 68 intraventricular non-CN tumours were analysed by one experienced neuroradiologist retrospectively to identify previously reported features and new features of CN. Six blinded radiologists independently reviewed all these MRI images, and scored all characteristic features on a five-point scale. Diagnostic value was assessed by the area under the receiver operating characteristic curve (AUC); sensitivity, specificity and accuracy were also calculated. RESULTS: In addition to the 'scalloping' sign, 'broad-based attachment' sign and 'soap-bubble' sign, three new MRI features of CN were identified, including the 'peripheral cysts' sign, 'fluid-fluid level' sign and the 'gemstone' sign. The scalloping sign showed the highest AUC value (0.82), followed by the peripheral cysts sign (0.75) and broad-based attachment sign (0.75). The scalloping sign exhibited the highest specificity (82%), followed by the fluid-fluid level sign (79%) and gemstone (78%) sign. The broad-based attachment sign (85%) was the most sensitive feature, followed by the soap-bubble sign (84%) and peripheral cysts sign (77%). CONCLUSION: There are six characteristic MRI features that help to improve the preoperative diagnostic accuracy of CN. KEY POINTS: • This study is the largest magnetic resonance imaging (MRI) cohort on central neurocytoma (CN). • Three new features helpful for the diagnosis of CN were reported. • Diagnostic value of six MRI features of CN was preliminarily determined.

Diffusion-weighted MRI combined with susceptibility-weighted MRI: added diagnostic value for four common lateral ventricular tumors.

Background Diffusion-weighted imaging (DWI) and susceptibility-weighted imaging (SWI) are reliable imaging modalities for brain tumors. However, the role of DWI and SWI in the diagnosis of common lateral ventricular tumors has not been systematically evaluated. Purpose To evaluate the diagnostic performance of DWI and SWI in common lateral ventricular tumors. Material and Methods Fifty-two patients with histopathologically confirmed lateral ventricular tumors were included in this study (18 with central neurocytomas, nine with ependymomas, seven with high-grade gliomas, and 18 with meningiomas). The relative minimum apparent diffusion coefficient (rADCmin) and relative average apparent diffusion coefficient (rADCave) measured by DWI and the intratumoral susceptibility signal intensity (ITSS) of hemorrhage acquired by SWI were calculated. These quantitative parameters were evaluated using the Mann-Whitney U test, receiver operating characteristic curve, and logistic regression analyses. Results The rADCmin and rADCave ratios of central neurocytomas were significantly lower than those of the other neoplasms. The rADCmin and rADCave ratios of ependymomas and the rADCave ratio of high-grade gliomas were significantly higher than those of meningiomas. The ITSS score of meningiomas was significantly lower than those of the other tumors, while the score of central neurocytomas was obviously lower than those of ependymomas and high-grade gliomas. The combination of the rADC ratio with the ITSS showed no significant difference, except in discriminating between meningiomas and high-grade glioma-ependymomas. Conclusion The rADC ratios and ITSS may be useful for differentiating common lateral ventricular tumors. The diagnostic performance may be improved with the use of the rADC ratios and ITSS scores.

A clinicopathologic study of extraventricular neurocytoma.

In 2007, extraventricular neurocytoma was classified as a separate entity among glioneuronal tumors. However, extraventricular neurocytoma is not fully understood and may be misdiagnosed. Here, we describe the clinical and pathological features, prognoses, and treatments of 13 extraventricular neurocytoma cases, and compare their immunophenotypes with those of oligodendroglioma, diffuse astrocytoma, and ependymoma. Six typical and 7 atypical cases comprised the 13 extraventricular neurocytoma cases. Histological features included oligodendroglioma-like perinuclear halo, neuropil-like matrix, ganglion or ganglioid cells, perivascular pseudorosettes, vessel hyalinization, calcifications, and myxoid degeneration. Atypical histological features included increased mitotic figures, focal necrosis, endothelial cell proliferation, and/or a Ki-67 index of >2%. All lesions expressed synaptophysin and microtubule-associated protein-2, which distinguished them from other similar tumors. Two patients with atypical extraventricular neurocytoma had tumor recurrence, one of whom had cerebrospinal fluid dissemination, suggesting that atypical histological features might represent adverse prognostic factors. In conclusion, the present study identified morphological and immunohistochemical features that would aid the differential diagnosis of extraventricular neurocytoma. In addition, radiotherapy with subtotal resection could be considered an effective treatment for extraventricular neurocytoma, but because a pediatric patient died of intracranial hemorrhage during radiotherapy, radiotherapy-related side effects should be considered, especially when treating children. Additional cases with long-term follow-up are needed to develop optimal management protocols for extraventricular neurocytoma.

Clinical, radiological, pathological and prognostic aspects of intraventricular oligodendroglioma: comparison with central neurocytoma.

Studies comparing intraventricular oligodendroglioma (IVO) and central neurocytoma (CN) in terms of their clinical, radiological and pathological features are scarce. We, therefore, investigated the similarities and differences between these types of tumors to get a better understanding of how they may be more properly diagnosed and treated. The clinical manifestations, CT/MRI findings, pathological characteristics and clinical outcomes of 8 cases of IVOs and 12 cases of CNs were analyzed retrospectively. Both IVO and CN occurred most commonly in young adults and manifested with symptoms of increased intracranial pressure secondary to obstructive hydrocephalus. However, they were radiologically different in location (p = 0.007), diffusion-weighted imaging (p = 0.001), "scalloping" appearance (p = 0.006), flow void sign (p = 0.006) and ventricular wall invasion (p = 0.000). Histologically, significant differences in mitotic count (p = 0.008) and parenchymal infiltration (p = 0.01) were noted. Immunohistochemically, significant differences in the expression of Olig2 (p = 0.000), Syn (p = 0.01) and NeuN (p = 0.000) were observed. In addition, MIB-1 labeling index (p = 0.035) and case fatality rate (p = 0.021) of IVO were much higher than those of CN, while survival rate of IVO was much lower than that of CN (p = 0.028). IVO and CN are similar in onset age and clinical manifestations, but have different imaging and pathological features. Patients with IVOs may have a relatively poorer prognosis compared to those with CNs.

Ventricular Central Neurocytoma: Rate of Shunting and Outcome 2 Years After Total and Subtotal Excision.

BACKGROUND: Central neurocytoma is an intraventricular tumor that affects young adults. It has a favorable prognosis after adequate surgical intervention; however, an aggressive course may take place in some cases. OBJECTIVE: The objective of the study was to evaluate the rate of shunting and the outcome of control measures in patients with central neurocytoma submitted to total and subtotal excision. METHODS: Twelve patients were included in this study, with a follow-up of 24 months. Data collected included: age, sex, clinical presentation, early morbidity and mortality, radiological findings (tumor location, features, residual, recurrence, and hydrocephalus). All patients underwent surgery for total or subtotal excision through a transcortical approach. External Ventricular Drain (EVD) was inserted then removed or replaced by a shunt. Histopathology and the MIB index were used to confirm diagnosis and guide the follow-up; adjuvant radiotherapy or Gamma Knife radiosurgery were used for residual tumor or recurrence. RESULTS: The ages of the patients ranged from 14 to 48 years. Two patients died early, after total and subtotal excision, from sepsis and thalamic infarction, respectively. Six patients (60 %) had a total excision; two of them had a high MIB index and showed small recurrence at 12 months and 18 months, respectively, and received Gamma Knife radiosurgery. One of the six patients with total excision needed a shunt, and no shunt was needed in the four otherpatients; a subtotal excision was done for four patients (40 %). An early shunt was inserted for two of these patients, radiosurgery-controlled for one patient, while radiotherapy was used for control in the other three patients; radiotherapy control failed in one patient, who underwent a second surgery at 18 months. CONCLUSION: Central neurocytoma may have a favorable prognosis, with a lower incidence of shunt insertion throughout its course than that for other intraventricular tumors, if total removal is achieved.

Cerebellar liponeurocytoma with extracranial extension: case report.

Cerebellar liponeurocytoma is a newly recognized, rare clinicopathological entity commonly described in the cerebellar hemispheres or the vermis. We present a rare case of cerebellar liponeurocytoma arising from the left cerebellar amygdala with extracranial extension. Such a condition has never been previously reported.

The role of single fraction Gamma Knife radiosurgery for intraventricular central neurocytomas and the utility of F-18 fluroethyltyrosine: two case reports.

BACKGROUND: Primary treatment of central neurocytomas is surgical resection. Gamma Knife surgery is considered a valuable therapeutic option in case of residual (after subtotal resection) or recurrent central neurocytomas. Here, we focused on the role of F-18 fluroethyltyrosine as a marker to document tumor progression after initial resection, in the context of an atypical central neurocytoma. We also describe MIB-1's role in evaluating therapeutic decision-making. CASE PRESENTATION: Two patients with central neurocytomas were treated by Gamma Knife surgery in our center. The first case (31-year-old Caucasian male) had atypical central neurocytoma. Four and a half years after surgical resection, magnetic resonance imaging and F-18 fluroethyltyrosine documented clear progression of residual central neurocytoma, further treated by Gamma Knife surgery (18 Gy at 50%, target volume 1.4 cc, and prescription isodose volume 1.8 cc). The initial post-Gamma Knife surgery clinical course was uneventful, with progressive volumetric reduction of residual tumor up to 4.5 years, when out-of-field recurrence was suspected and confirmed by local F-18 fluroethyltyrosine hyperactivity. Second single-fraction Gamma Knife surgery was performed (18 Gy at 50%, target volume 0.49 cc, prescription isodose volume 0.72 cc). The second (32-year-old Caucasian female) had previous subtotal resection and typical central neurocytoma. Seven years later, she had residual tumor progression. Single-fraction Gamma Knife surgery was performed (16 Gy at 50% isodose line, target volume 1.7 cc, and prescription isodose volume 2.5 cc). Last follow-up showed tumor volume reduction. Follow-up magnetic resonance imaging showed important volumetric reduction of both treated lesions. CONCLUSIONS: In atypical central neurocytomas, F-18 fluroethyltyrosine could be used as postoperative examination to detect small tumor remnants, follow-up evaluation following the Gamma Knife surgery or, in select cases, following surgical resection. The role of MIB-1 is important in therapeutic decision-making, as tumors with MIB-1 exceeding 2% are characterized by more aggressive clinical course. Single-fraction Gamma Knife surgery remains a valuable therapeutic option for postoperative residual atypical central neurocytomas and central neurocytoma recurrences.

Extraventricular neurocytoma at the sellar region: Report of 8 cases and literature review.

BACKGROUND: Extraventricular neurocytoma at the sellar region (EVNSR) is an exceedingly rare tumor. Given the paucity of specificity and its peculiar nature, our study aimed to characterize the clinical, imaging, and pathological features, including treatment and clinical outcomes of this tumor. METHOD: Eight patients with pathologically confirmed EVNSR at Beijing Tiantan Hospital from 2012 to 2020 were retrospectively analyzed. Additionally, 7 cases from the prior detailed literature were also retrieved. FINDINGS: Among the 8 patients from Beijing Tiantan Hospital, 2 males and 6 females with an average age of 45.3 (range, 8-61). Vision impairment and headache were the most common complaints at presentation. Preoperative diagnoses were pituitary adenoma (n = 6), meningioma (n = 1), and oligodendroglioma (n = 1). Treatment included subtotal tumor resection (n = 3), partial resection (n = 5), adjuvant therapy covered radiotherapy (n = 2), and gamma knife surgery (n = 3). The clinical outcomes of these 8 cases were stable (n = 5), survival after progression (n = 1), and death after recurrence (n = 2). CONCLUSIONS: EVNSRs are extremely rare tumors, and most have benign prognoses after appropriate treatment. Due to the unique location, total removal of the tumor is challenging; And adjuvant radiation therapy for eligible patients is recommended. Regular imaging review is also advised. Future studies with more patients are needed to elucidate the biological nature of EVNSRs.

MR Finding of Extraventricular Neurocytoma.

OBJECTIVE: To determine the MR (magnetic resonance), pathologic, and clinical findings of extraventricular neurocytoma (EVN). STUDY DESIGN: Descriptive study. PLACE AND DURATION OF STUDY: Department of Radiology, Affiliated Hospital of Jining Medical University, Jining, Shandong, China, from January 2020 to March 2022. METHODOLOGY: The MR radiological and pathological data of 11 patients with EVNs proved by histopathology after surgery were analysed retrospectively. Above-mentioned features were studied. RESULTS: There were 5 men and 6 women, ages ranging from 16 to 56 years. Seven cases (63.6%) were located in the cerebral hemisphere, three cases (27.3%) in the cerebellar hemisphere, and one case in cervical cord. Ten cases (91.0%) were cystic-solid, and one case was predominantly solid with small cystic components. Six cases (54.5%) had mild peritumoural ooedema. The signal was isointense (8/11, 72.7%) or hypointense (3/11, 27.3%) on T1WI, and isointense (1/11, 9.1%) or hyperintense (10/11, 90.9%) on T2WI; all cases showed hyperintense on FLAIR and restricted diffusion on DWI. Haemorrhage was found in two cases (18.2%) and flow-void was found in one case (9.1%). All the tumours demonstrated contrast enhancement. CONCLUSION: An accurate diagnosis of EVN is difficult to be made preoperatively. It should be considered when a solid-cystic tumour with the solid part showing isointense on T1WI, hyperintense on FLAIR with mild to moderate enhancement especially restricted diffusion on DWI sequence in patients aged 20-30. When the radiologic manifestations are atypical, more aggressive treatment should be chosen. KEY WORDS: Neurocytoma, Extraventricular, Clinical, Imaging characteristics, MRI.