Central neurocytoma. A clinicopathological, immunohistochemical and ultrastructural study of 7 cases

Central neurocytomas in children: Clinicopathologic features and long-term surgical outcomes

PURPOSE

Pediatric central neurocytomas (PCNs) is an extremely rare entity, and very few reports have exclusively focused on the clinicopathologic features and surgical outcomes of PCNs.

METHODS

This study was undertaken to elucidate the clinical and pathological characteristics and long-term surgical outcomes of PCNs.

RESULTS

Fourteen consecutive patients with pathologically verified PCNs were identified, including 9 girls and 5 boys, with a mean age of 15.2 ± 3.9 years (range 3-18 years). Children tended to present with symptoms of increased intracranial pressure (ICP) (p = 0.003), an acute clinical course (p = 0.044), and a shorter duration of symptoms (p = 0.019) than their adult counterparts. Surgery was performed under the guidance of a neuronavigation system and intraoperative ultrasound; gross total resection (GTR) was achieved in 12 patients (85.7%), and subtotal resection (STR) was achieved in two patients (14.3%). One child received adjuvant radiotherapy (RT) owing to the atypical features of the lesion. During a mean follow-up of 90.2 ± 37.0 months (range 42-156 months), one patient (7.1%) with atypical features experienced lesion relapse 2 years after surgery and received RT, and the symptoms of all children were relieved.

CONCLUSION

Surgery can benefit children with CNs and ensure relatively long-term progression-free survival. RT can be administered to patients with residual or relapsed lesions.

Pediatric central neurocytoma: Case report and review of literature

Central neurocytomas are slow-growing primary brain tumors of neuronal origin having a predilection to arise mostly in the lateral ventricles. We report a case of a 9-year-old girl who presented with headache and vomiting of 1-month duration. Her magnetic resonance imaging was suggestive of central neurocytoma of the third ventricle and was surgically managed, and tumor tissue was sent for histopathology and immunohistochemistry which confirmed the diagnosis.

Central Versus Extraventricular Neurocytoma in Children: A Clinicopathologic Comparison and Review of the Literature

BACKGROUND

Central neurocytomas (CN) are rare pediatric CNS tumors most often with a benign clinical course. Occasionally, these tumors occur outside the ventricles and are called extraventricular neurocytomas (EVN). We present a retrospective institutional analysis of children with neurocytoma with prolonged follow-up.

PROCEDURE

Twelve patients were diagnosed with neurocytoma at our institution between 1993 and 2004.

RESULTS

Six patients were male and the median age at diagnosis was 12 years (1.5 to 16 y). Seven patients had CN and 5 had EVN. Presenting symptoms included headaches (67%), vomiting (50%), nausea (33%), seizures (33%), and mental status changes (25%). Obstructive hydrocephalus was present at diagnosis in 42% of the cases. Younger age and seizures were more common in patients with EVN. Gross total resection (GTR) was achieved in 42% (5/12) of the patients. Patients with GTR received no adjuvant therapy upfront; 1 patient subsequently had recurrence with leptomeningeal disease. Patients with subtotal resection received additional treatment: 1 underwent reoperation (GTR), 2 patients received focal radiation, 2 patients received adjuvant chemotherapy, and 2 patients received craniospinal irradiation followed by chemotherapy. The 20-year overall survival for this cohort was 83% with event free survival of 56%. Overall survival for CNs was 100%, versus 40% for EVN. Event free survival for CNs was 57% and 53% for the EVNs. An MIB-1 fraction >2% was associated with worse prognosis.

CONCLUSIONS

Neurocytomas are rare brain tumors in children usually cured with GTR. Adjuvant focal radiation therapy and/or chemotherapy may improve disease control in cases with subtotal resection, but case-by-case analysis should be done. EVNs might be associated with worse outcome due to a higher proliferative index.

Central, Extraventricular and Atypical Neurocytomas: a Clinicopathologic Study of 35 Cases from Pakistan Plus a Detailed Review of the Published Literature

BACKGROUND

Central neurocytomas are rare neuronal neoplasms with a favorable prognosis. They are typically located in the lateral ventricles of the brain and mostly histologically correspond to WHO grade II with a Mib 1 labelling index of <2%. Similar tumors located in the cerebral hemispheres and spinal cord, for example, are called "extraventricular neurocytomas". A few tumors histologically show atypia, mitoses, vascular proliferation and/or necrosis and a Mib 1 index >2 % and are designated as "atypical neurocytomas.

AIM

The aim of our study was to describe the common as well as unusual morphologic features and the role of various immunohistochemical stains in the diagnosis of these rare tumors.

MATERIALS AND METHODS

We retrieved and reviewed 35 cases diagnosed between 2001 and 2015.

RESULTS

Sixty percent of patients were males, and the mean age was 26 years. 31 cases (88.6%) were intraventricular and 4(11.4%) were extraventricular. Histologically, 6 cases (17.1%) were compatible with "atypical neurocytomas". All cases showed the classic morphology comprising nests and sheets of uniform, round cells with uniform round to oval nuclei with finely speckled chromatin and perinuclear cytoplasmic clearing (halos). All cases also showed delicate, fibrillary, neuropil-like matrices. Other common histologic features included capillary-sized blood vessels in a branching pattern in 57.1%, foci of calcification in 34.3% and perivascular pseudorosettes in 20%. Rare findings included Homer- Wright or true rosettes in 8.6% and ganglioid cells in 2.9%. Synaptophysin was the most consistent and valuable marker, being positive in almost all cases. GFAP positivity in tumor cells was seen in 25.7% of cases. Follow up was available in 13 patients. Of these 9 had histologically typical and 4 had atypical tumors. Only 1 (with an atypical neurocytoma) died, probably due to complications of surgery within one month, while 12 (including 3 with atypical neurocytomas) remained alive. Recurrence developed in 1 of these 12 patients (histologically consistent with typical morphology) almost 9 years after surgery. Only 4 patients, including 2 with atypical tumors, received postoperative radiotherapy, all with surgery in 2010 or later. Overall, prognosis was excellent with prolonged, recurrence free survival and most patients, even without receiving radiation therapy, were alive and well for many years, even a decade or more after surgery, without developing any recurrence, indicating the benign nature of these neoplasms.

Clinical manifestations of central neurocytoma

Central neurocytomas (CNs) are rare central nervous system tumors that occur in the lateral ventricles. They are prevalent in young adults and are typically benign with excellent prognosis following surgical resection. Because of the rarity of the disease and its similar features with more common tumors, misdiagnosis becomes an issue. Optimal treatment is achieved only when the correct tumor types are distinguished. Typical clinical manifestations include symptoms of increased intracranial pressure, although no clinical feature is pathognomonic to CN. Radiologic imaging, histology, magnetic resonance spectroscopy, and immunohistochemistry must be used to elucidate tumor characteristics and properly diagnose CN.

A comparative study of intraventricular central neurocytomas and extraventricular neurocytomas

Similar histology and clinical behavior of both intraventricular central neurocytomas (CNs) and extraventricular neurocytomas (EVNs) may argue against the idea that EVNs were the distinct entity to distinguish from CNs in the 2007 World Health Organization classification. To explore respective characteristics and compare similarities and differences in CNs and EVNs, relevant clinical, radiological, operative and pathological data of 49 patients (35 CNs and 14 EVNs) in the Department of Neurosurgery at our hospital from 2005 to 2012 was reviewed and some comparisons between CNs and EVNs were conducted. The factors affecting posttreatment recurrence of CNs and EVNs were assessed by Cox regression analysis. In comparison, CNs showed a more typical clinical manifestation, and radiological and histopathological features, while EVNs demonstrated more malignant biological behavior, with higher MIB-1 index (p = 0.006), higher rate of atypia (p = 0.042), higher recurrence rate (p = 0.028), and shorter time to recurrence (p = 0.049). Subtotal resection was associated with higher rates of recurrence in both CNs (hazard ratio [HR] 6.16, p = 0.046) and EVNs (HR 5.26, p = 0.045), and atypia was also associated with a higher recurrence rate in CNs (HR 5.03, p = 0.042). CNs were thus easier to diagnose than EVNs, with typical clinical, radiological, and histopathological features, while the latter were more likely to show malignant biological behavior associated with atypia and recurrence. Total surgical resection is the optimal treatment choice for both CNs and EVNs, and patients with either CN or EVN with typical and/or totally resected lesions showed favorable clinical outcomes.

From the radiologic pathology archives: intraventricular neoplasms: radiologic-pathologic correlation

A variety of neoplasms may arise in the ventricular system. Intraventricular neoplasms may be discovered as an incidental finding at cross-sectional imaging or may manifest with varied symptoms depending on their location, including symptoms of increased intracranial pressure. These lesions may arise from various ventricular structures, including the ependymal lining (eg, ependymoma), subependymal layer (eg, subependymoma), or choroid plexus (eg, choroid plexus neoplasms), or they may have a cell of origin that has yet to be determined (eg, chordoid glioma). Other neoplasms involving the ventricular system include central neurocytoma, subependymal giant cell tumor, meningioma, rosette-forming glioneuronal tumor, and metastases. The differential diagnosis for intraventricular neoplasms can be broad, and many of them have similar patterns of signal intensity and contrast enhancement at imaging. However, the location of the lesion in the ventricular system-along with knowledge of the patient's age, gender, and underlying conditions-will help narrow the differential diagnosis.

Neurocytoma of the cerebellum

Background:

Neurocytomas are benign central nervous system tumor composed of small cells with characteristics of neuronal differentiation; they are usually located in the supratentorial periventricular region, in close relation to the septum pellucidum and the foramen of Monro.

Case Description:

Herein we report a rare case of a neurocytoma located in the cerebellar hemisphere. To date there are only four such reported cases.

Conclusion:

Neurocytomas should be considered in the differential diagnosis of mass lesions in the cerebellum.

Clinicopathological analysis of central and extraventricular neurocytoma: a report of 17 cases

Neurocytoma, a rare brain tumor, is characterized by a mass located mainly in cerebral ventricles. It is prone to be misdiagnosed as oligodendroglioma or ependymoma due to their similar histopathological features in clinical practice. This study aimed to examine the clinicopathological features and differential diagnosis of central and extraventricular neurocytoma. The clinical and histopathological data of 17 patients (male: female=7:10; age: 4-41 years; mean age: 27.4 years) with central or extraventricular neurocytoma were retrospectively analyzed. These patients showed typical radiological, histopathological and immunohistochemical features of neurocytoma. The tumor tissue was found to be composed of small uniform cells with round nuclei and clear cytoplasm resembling that of oligodendroglioma and ependymoma. Immunohistochemistry revealed the tumor tissues were positive for neuronal markers such as synaptophysin (SYN) and neuronal nuclear antigen (NeuN). It was concluded histopathological features of neurocytoma overlaps with some tumors in the central neural system. Immunopositivity for SYN and NeuN can help differentially diagnose neurocytoma.

Endoscopic removal of a central neurocytoma from the posterior third ventricle

Central neurocytoma is a rare benign tumor that most commonly arises within the ventricular system of young adults. Its occurrence in the posterior third ventricle is one of the least reported presentations. These tumors are usually treated by a combination of either biopsy or open surgical resection, often followed by radiation (Gamma knife or Novalis) with or without chemotherapy. A 37-year-old woman with a posterior third ventricle neurocytoma presented with acute signs of aqueductal stenosis. The patient underwent endoscopic assisted gross total resection of the tumor with the aid of intraoperative laser followed by standard third ventriculostomy; no further treatment was required. The patient did not develop any subsequent neurological deficit. A 36-month follow-up was still consistent with a normal neurological examination. Serial post-operative MRIs show neither residual nor recurrent tumor. Thus, posterior third ventricle central neurocytomas are relatively benign tumors that can be successfully removed using a minimally invasive approach, thereby avoiding both the morbidity related to conventional open craniotomy and the potential toxicity of any adjuvant treatment.

Central neurocytoma: the neuroradiological perspective

BACKGROUND

Central neurocytoma (CN) represents a rare, relatively recently described primary central nervous system tumor. It ranks among intraventricular tumors due to its predominant location within the lateral brain ventricles. CN occurs mostly in young adults around the 3rd decade of life; almost a fifth of the cases are children under 18 years of age.

OBJECTIVES

The authors present three cases of patients with histopathologically confirmed CN, emphasizing diagnostic imaging issues. A review of the literature concerning differential diagnosis and clinical and therapeutic aspects is also presented.

CONCLUSION

Literature reports of CN comprise most likely case reports, small cohorts of patients, and meta-analytic studies due to the generally low incidence of this tumor. In the current paper, the authors summarize up-to-date knowledge of this rare disease on the background of their own observations. CN should be included in the list for differential diagnostics of intraventricular brain tumors, especially those located in lateral ventricles.

Central neurocytoma: Management recommendations based on a 35-year experience

PURPOSE

To examine the outcomes of patients with histologically confirmed central neurocytomas.

METHODS AND MATERIALS

The data from 45 patients with central neurocytomas diagnosed between 1971 and 2003 were retrospectively evaluated. Various combinations of surgery, radiotherapy (RT), and chemotherapy had been used for treatment.

RESULTS

The median follow-up was 10.0 years. The 10-year overall survival and local control rate was 83% and 60%, respectively. Patients whose tumor had a mitotic index of <3 (per 10 high-power fields) experienced a 10-year survival and local control rate of 89% and 74%, respectively, compared with 57% (p = 0.040) and 46% (p = 0.14) for patients with a tumor mitotic index of > or =3. The 10-year survival and local control rate was 90% and 74% for patients with typical tumors compared with 63% (p = 0.055) and 46% (p = 0.41) for those with atypical tumors. A comparison of gross total resection with subtotal resection showed no significant difference in survival or local control. Postoperative RT improved local control at 10 years (75% with RT vs. 51% without RT, p = 0.045); however, this did not translate into a survival benefit. No 1p19q deletions were found in the 19 tumors tested.

CONCLUSION

Although the overall prognosis is quite favorable, one-third of patients experienced tumor recurrence or progression at 10 years, regardless of the extent of the initial resection. Postoperative RT significantly improved local control but not survival, most likely because of the effectiveness of salvage RT. For incompletely resected atypical tumors and/or those with a high mitotic index, consideration should be given to adjuvant RT because of the more aggressive nature.

Atypical neurocytoma of the spinal cord in a young child

BACKGROUND

Extraventricular neurocytoma is a well-established entity, and non-classical sites like the cerebellum and spinal cord have occasionally been reported.

CASE

We report a rare case of intramedullary neurocytoma in an 8-year-old boy who presented with paraparesis and urinary incontinence. This tumour was isointense on T1-weighted image and hyperintense on T2-weighted image, and showed heterogenous contrast enhancement.

FINDINGS

Pathological examination showed atypical histology in the form of vascular endothelial proliferation, increased proliferation index, mitosis and necrosis.

CONCLUSIONS

Atypical location, younger age and histopathological features are some of the interesting findings in this case, which need to be documented. To the best of our knowledge, this is the youngest patient of spinal cord neurocytoma.

Central neurocytoma: two case reports and review of the literature

Central neurocytomas are low grade tumours usually located in the lateral ventricles next to Monro foramina. This paper reviews the literature on central neurocytomas observed in the last few years and discusses their clinical, histopathological, immunohistochemical and genetic characteristics. Important correlations between therapeutic strategies and biological findings as well as new genetic discoveries are also discussed. Two illustrative cases in which the authors report preliminary results about molecular analysis of some genetic markers are described.

Neurocytoma: a comprehensive review

Central neurocytomas (CN) are uncommon tumors of the central nervous system, most descriptions of which available in the literature are in the form of isolated case reports and small series. Owing to this rare incidence, diagnosis and management of this neoplasm remain controversial. Usually, these tumors affect lateral ventricles of young adults and display characteristic neuroimaging and histomorphologic findings. Neurocytomas often mimic oligodendrogliomas when confirmation of diagnosis rests on immunohistochemistry, ultrastructure, and genetic studies. Extraventricular neurocytomas, situated entirely within the brain parenchyma and spinal cord, have also been reported. Typically, CN are associated with a favorable outcome although cases with more aggressive clinical course with recurrences are not unknown. MIB-1 labeling index (LI) of >2% often heralds poor prognosis and tumour recurrence. Safe maximal resection is presently considered the ideal therapeutic option, with best long-term prognosis in terms of local control and survival. The role of adjuvant radiotherapy apparently seems to benefit patients with incomplete resection and in atypical neurocytoma. Utility of other therapeutic regimen, however, remains shrouded in controversy. Epidemiology, histogenesis, clinical profile, histology, neuroimaging and therapeutic modalities of neurocytomas have been comprehensively reviewed, with special emphasis on CN and extraventricular neurocytomas and their atypical counterparts.

Central neurocytoma: a novel appraisal of a polymorphic pathology. Our experience and a review of the literature

Central neurocytoma should be considered in the differential diagnosis of intraventricular tumours. The records of 20 patients operated on between 1975 and 2000 for central neurocytoma were retrospectively reviewed, and the histological gradings and clinical outcomes were compared. On the basis of our previous cases, in the latter five of this series, the following therapeutic protocol was adopted. In those cases in which total removal was achieved, no further treatment was given if the MIB-1 index was <4%; vice versa, if it was >4%, a course of conformational radiotherapy was delivered. In subtotally removed cases, radiosurgery with linac was also performed (median dose 20 Gy) as well as conformational radiotherapy whenever there was a recurrence of the lesion (median dose 45 Gy). In cases in which there was only partial cytoreduction, conformational radiotherapy was administered with the adjunct of polychemotherapy if the MIB-1 was >4%. Twenty patients were surgically treated: 11 men and nine women, with an average age of 26 years (range 17 years to 42 years).Total, subtotal and partial removals were achieved in, respectively, ten, three and seven cases. At average follow-up of 7 years, 16 patients had been cured, had significantly improved or were at least stable [Karnofsky performance status score (KPS)] >70 or more)]. On the other hand, four patients had worsened; of these, two had died and two had a KPS=50 and an unfavourable prognosis. The presence of histological atypia has proved to be a significantly negative risk factor for survival (P=0.02) while an MIB score >4% was significantly correlated with an unfavourable outcome (death or worsening of neurological status). The "atypical" neurocytoma seems to be a distinct entity, with a less favourable prognosis and a higher tendency to recur.

Central neurocytoma: report of two cases

INTRODUCTION: Central neurocytomas are rare neuroectodermal tumors believed to arise from the subependymal matrix of the lateral ventricles. CASE REPORTS: A 26-year-old woman and a 33-year-old man each had a large, heterogeneous, contrast enhancing mass in the lateral ventricles at the foramen of Monro causing bilateral hydrocephalus. The woman died after surgery, but the man is asymptomatic after three years. HISTOPATHOLOGY: Both tumors were composed of isomorphic rounded cells positive for synaptophysin, chromogranin and NSE, while some reacted for GFAP, vimentin and S-100 protein. Electron microscopy revealed neuropil-like tissue between cells, but synapses were rare.

Intraventricular neurocytomas

The literature to date on the treatment of CNC reflects an evolution of clinical practice in neurooncology. The advent of sophisticated tools, such as MRS and molecular pathology, has facilitated more efficient diagnosis of CNC. Decreased morbidity associated with surgical intervention has resulted in better outcomes in patients undergoing resection of CNC. Prospective monitoring of treated patients with MRI coupled with judicious use of radiosurgery will likely further decrease treatment-related morbidity.

Peritoneal dissemination from central neurocytoma: case report

OBJECTIVE

Central neurocytoma is a low grade tumor of neuroglial origin and a relatively new histological entity. Only a few cases have been reported and its biological behavior is still uncertain. Some cases have shown an aggressive behavior (local recurrence, malignant dedifferentiation or CSF dissemination) and challenged the initial view of its relative benignity. A case of central neurocytoma with peritoneal dissemination is presented.

CASE

A six years-old boy with recurrent neurocytoma of III ventricle and left thalamus showed fast growth of tumor rest and ascites three and a half years after subtotal removal of the lesion. Tumor cells were identified in the ascitic fluid and implanted in the peritoneum. Chemotherapy was initiated immediately after diagnosis of peritoneal dissemination (etoposide, carboplatin, doxorubicin and cyclophosphamide). The patient developed metabolic imbalance and respiratory failure due to rapid formation of ascitic fluid and died 3 days after the diagnosis of peritoneal dissemination was established.

CONCLUSION

Central neurocytoma is a low grade tumor with low values of the proliferative index in the majority of cases. In spite of that, some tumors may present a very aggressive behavior and extraneural dissemination. Evaluation of proliferative index may be a guideline parameter for planning adjuvant therapies after surgical treatment in selected cases. Extraneural dissemination may occur in some cases specially in patients with ventriculoperitoneal shunt.

Epidemiology and pathology of intraventricular tumors

Tumors that primarily or exclusively involve the ventricular system constitute a rare and heterogeneous group. Certain histologic tumor types predominantly occur in children, whereas others are more common in adults. Tumor location provides additional clues to correct diagnosis. When used in conjunction with clinical and radiologic data, histopathologic features can distinguish among this wide range of possibilities to provide the correct diagnosis for optimal patient management.

Extraventricular neurocytoma: morphological and immunohistochemical considerations on differential diagnosis

Neurocytoma is an unusual neuronal tumor especially affecting young people. It commonly arises in the ventricles and has a benign outcome. Herein, we report on a rare case of extraventricular neurocytomas (right parietal lobe) in a young girl admitted to hospital for a cranial trauma subsequent to a seizure. The tumor, radiologically well-circumscribed, cystic and enhancing, was surgically excised. The patient, who received no post surgical treatment, is alive and well after 18 months of follow-up. Pathological examination showed a well-differentiated lesion composed of uniform, round cells with perinuclear halos in a neuropil background and immunohistochemically positive for neuronal markers (synaptophysin, neuron-specific enolase, neurofilaments). The authors emphasize the role of the morphological and immunohistochemical evaluations to recognize this rare tumor.

Central neurocytoma with craniospinal dissemination

Central neurocytoma was first described by Hassoun et al. in 1982. The tumor is a rare benign tumor of the central nervous system, usually located in the lateral ventricles. Most reported cases are histologically and clinically benign. Several cases with recurrence have been described. Including the case presented here, only seven cases with craniospinal dissemination have been reported. None of the previous cases with dissemination had histological atypia but most did have a high MIB-1 labeling index (MIB-1 LI). Our patient had a high MIB-1 LI (4.6%) and dissemination was found to have advanced through the anterior horns of the lateral ventricles and to the spinal cord at the T4 level. The patient underwent partial resection of the tumor with follow-up radiation treatments for the residual tumor and dissemination. After the radiation, the size of the tumor decreased. The report of this casewill be helpful in the treatment of disseminated central neurocytoma.

Defining the optimal dose of radiation after incomplete resection of central neurocytomas

PURPOSE

Central neurocytomas are uncommon benign central nervous system tumors. There is uncertainty regarding the most appropriate radiation dose after incomplete resection. This analysis was performed to determine the optimal dose.

METHODS AND MATERIALS

All cases reported since 1982 were reviewed for age, gender, resection status, total dose, dose per fraction, local control, and overall survival. Additional data were obtained from the authors. The inclusion criteria were incomplete resection, postoperative irradiation, complete data, and 12 months' minimal follow-up. Two groups were formed according to the equivalent dose in 2-Gy fractions (EQD2): group A (40.0-53.6 Gy) and group B (54.0-62.2 Gy). Local control and survival were compared using Kaplan-Meier analysis and the log-rank test.

RESULTS

Eighty-nine patients (group A 42, group B 47) met the inclusion criteria. At 5 years, the local control rate was 98% for group B vs. 69% for group A. At 10 years, it was 89% vs. 65% (p = 0.0066). The 5- and 10-year survival rate was 98% for group B vs. 88% for group A (p = 0.1).

CONCLUSIONS

Our data suggest that a EQD2 > or =54 Gy significantly improves local control in patients with subtotally resected neurocytomas. Although the difference in survival was not significant, a trend toward better survival was noted after a EQD2 of > or =54 Gy.

Fourth ventricle central neurocytoma: case report

OBJECTIVE AND IMPORTANCE

Central neurocytomas (CNs) are typically located in the lateral ventricle. Primary origins in the fourth ventricle are very rare. We discuss the clinical symptoms, imaging findings, and microscopic features of these rare tumors.

CLINICAL PRESENTATION

We report a case of a fourth ventricle CN in a 35-year-old male patient with the initial symptoms of progressive headaches and blurred vision for more than 2 months. Computed tomography and magnetic resonance imaging of the brain revealed a slightly enhanced tumor in the fourth ventricle, with obstructive hydrocephalus.

INTERVENTION

Total surgical removal of the tumor was performed. The tumor was initially diagnosed as an oligodendroglioma. The final definitive diagnosis as a CN was made after special immunohistochemical studies.

CONCLUSION

CNs located in the fourth ventricle are extremely rare. Immunohistochemical stains and transmission electron microscopy can provide useful diagnostic information. Total tumor excision is associated with favorable prognoses. Postoperative radiotherapy may be considered for cases of subtotal excision, anaplastic histological variants, or recurrent tumors.

Stereotactic radiosurgery for residual neurocytoma. Report of four cases

The purpose of this report was to review the results of stereotactic radiosurgery in the management of patients with residual neurocytomas after initial resection or biopsy procedures. Four patients underwent stereotactic radiosurgery for histologically proven neurocytoma. Clinical and imaging studies were performed to evaluate the response to treatment. Radiosurgery was performed to deliver doses to the tumor margin of 14, 15, 16, and 20 Gy, depending on tumor volume and proximity to critical adjacent structures. More than 3 years later, imaging studies revealed significant reductions in tumor size. No new neurological deficits were identified at 53, 50, 42, and 38 months of follow up. The authors' initial experience shows that stereotactic radiosurgery appears to be an effective treatment for neurocytoma.

Extraventricular neurocytomas: pathologic features and clinical outcome

Neurocytic neoplasms usually arise within the lateral ventricles, generally as circumscribed, slowly growing masses curable by total resection. Both subtotal resection and histologic atypia are associated with an increased risk of recurrence. In contrast, neurocytic neoplasms situated within brain parenchyma, so-called "extraventricular neurocytomas" (EVNs), are not as well characterized. The relationships between histologic features and extent of resection versus clinical behavior have not been defined. We evaluated pathologic features, clinical data, and neuroimaging of 35 examples. The tumors occurred in 18 males and 17 females, age 5-76 years (median 34 years). All tumors involved the cerebrum. On imaging, EVNs were solitary, variably contrast-enhancing, and often (57%) cystic. Tumor cells were arranged in sheets, clusters, ribbons, or rosettes, in association with fine neuropil dispersed in broad zones that separated cell aggregates. Ganglion cell differentiation was seen in 66%. All tumors showed strong synaptophysin immunoreactivity. Despite the lack of apparent astrocytes in hematoxylin and eosin-stained sections, focal glial fibrillary acidic protein reactivity was seen in 46%. Eleven EVNs were designated "atypical" based on the presence of necrosis, vascular proliferation, or elevated mitotic activity (> or = 3 mitoses/10 high power fields). Nineteen tumors were subtotally resected or biopsied, whereas 14 were totally resected grossly. Seventeen patients underwent radiotherapy (mean 55 Gy). In 30 cases with follow-up, 10 tumors recurred, 3 causing death at 6, 14, and 43 months. All 10 recurrences followed subtotal resection. No totally resected tumors recurred. Thus, the majority of EVNs are well differentiated and appear unlikely to recur after gross total resection. Subtotal resection, atypical histologic features, and high cell proliferation rates correlate with recurrence.

A neurocytoma and an associated lenticulostriate artery aneurysm presenting with intraventricular hemorrhage: case report

OBJECTIVE AND IMPORTANCE

Hemorrhage associated with central neurocytoma has been described previously, but never in association with an aneurysm originating from a feeding artery. We present the first reported case of a central neurocytoma in a patient with intraventricular hemorrhage caused by rupture of an aneurysm on a lenticulostriate artery that supplied the tumor.

CLINICAL PRESENTATION

A 35-year-old man who presented with an intraventricular hemorrhage underwent magnetic resonance imaging and cerebral angiography that disclosed a right lateral intraventricular mass and a 7-mm fusiform aneurysm from a lateral lenticulostriate branch of the right middle cerebral artery.

INTERVENTION

The patient underwent a contralateral transcallosal exploration and resection of the tumor, with excision of the adjacent lenticulostriate artery aneurysm. Pathological review demonstrated that the tumor was a neurocytoma. The aneurysm was discrete from the tumor but occurred on a vessel that supplied the tumor.

CONCLUSION

Previous reports have demonstrated that intraventricular neurocytoma may present with tumor hemorrhage. In this case, an aneurysm separate and distinct from the tumor was the bleeding culprit, and the aneurysm was on an artery that fed into the tumor. Any such aneurysm must be identified and treated appropriately for therapy to be complete.

Radiosurgery for the treatment of recurrent central neurocytomas

OBJECTIVE

Central neurocytomas are benign neoplasms with neuronal differentiation typically located in the lateral ventricles of young adults. Although the treatment of choice is complete surgical excision, patients may experience local recurrence. Adjuvant therapy for patients with residual or recurrent tumor has included reoperation, radiotherapy, or chemotherapy. To avoid the side effects of conventional radiotherapy in young patients, we present a series of patients with clear evidence of tumor progression who were treated with gamma knife radiosurgery.

METHODS

Four patients (ages 20-49 yr; mean, 28 yr) who presented with an intraventricular mass on magnetic resonance imaging scans and underwent craniotomy for tumor resection were reviewed retrospectively. Histopathological analysis confirmed central neurocytoma in all cases. Each patient was followed up clinically and radiographically with serial magnetic resonance imaging. When radiographic signs of tumor progression were evident, patients were treated with radiosurgery.

RESULTS

Complete radiographic tumor resection was achieved in all patients. There were no major postoperative complications. Local tumor progression was detected on magnetic resonance imaging scans 9 to 25 months after surgery (median, 17.5 mo). All patients achieved complete response to radiosurgery with reduction in tumor size. There have been no complications from radiosurgery. Follow-up ranged from 12 to 28 months (mean, 16.5 mo) after radiosurgery, and from 24 to 84 months (mean, 54.5 mo) after initial presentation.

CONCLUSION

Radiosurgery with the gamma knife unit provides safe and effective adjuvant therapy after surgical resection of central neurocytomas. Radiosurgery may eliminate the need for reoperation and avoid the possible long-term side effects from conventional radiotherapy in young patients.

Central neurocytoma: long-term follow-up of a paediatric case

In order to gain a better understanding of the clinical and histological features of central neurocytoma and the role of radiotherapy in the treatment of these tumours, we present an unusual paediatric case and review the pertinent literature. Most patients present in the second and third decade of life, rarely in the teenage years and exceptionally in children. Our patient was treated by a combined surgical and radiation therapy treatment for a central neurocytoma at the age of 7 years, but the tumour had been diagnosed when she was 3 years old. At a 38-year follow-up, she is well with no evidence of tumour progression. This patient seems to be the youngest histologically proven case of central neurocytoma and with the longest recorded survival.

So-called malignant and extra-ventricular neurocytomas: reality or wrong diagnosis? A critical review about two overdiagnosed cases

Central neurocytoma (CN) is described as a rare intra-ventricular benign neuronal tumor of the brain. Two primary tumors first diagnosed as malignant and extra-ventricular neurocytomas are reported here. Histologically, the tumor of the first patient, a forty-one-year-old man, consisted of monotonous cells with round nuclei, but no fibrillar background. The second tumor, in a nineteen-year-old girl, showed areas of moderately pleomorphic round cells, with numerous rosettes and ganglion cell differentiation, in an abundant fibrillary network. Both presented calcifications. Mitoses were more frequent in recurrences and spinal locations than in the primaries. All tumors stained strongly for synaptophysin, and GFAP was partly positive in the first case only. Patients received post-surgical radiotherapy and were still alive eight and six years, respectively, after initial surgery. The interpretation of atypical cases, such as ours is not easy: the diagnoses finally retained were oligodendroglioma in the first case and ganglioneuroblastoma in the second case. Furthermore, neurocytomas atypical either by their unusual topographical or histological presentation or by their poor prognosis, have been frequently entitled in this way on synaptophysin positivity. So, we were prompted to reassess the entity of CN, seventeen years after the first description, to re-appreciate the reality of anatomo-clinical variants and to discuss the value of synaptophysin positivity in these tumors. In conclusion, it seems preferable to individualize true classical CN, which has a favorable outcome, from so-called extra-ventricular, atypical and anaplastic, clinically malignant neurocytomas for which complementary treatment is required.

Central neurocytoma: histologic atypia, proliferation potential, and clinical outcome

BACKGROUND

Although central neurocytomas are considered benign, recent reports suggest that some patients with histologic atypia and/or elevated proliferation potential may have a poor outcome.

METHODS

A retrospective review identified 15 cases of central neurocytoma. Clinical follow-up was available for 14 patients. Each tumor was evaluated for the presence of atypical histologic features, including cellular pleomorphism, endothelial proliferation, and necrosis. The proliferation potential was assessed by MIB-1 immunohistochemistry. The correlation among histology, MIB-1 labeling index (MIB-1 LI), and clinical outcome was evaluated.

RESULTS

Histologic atypia was identified in 3 tumors (20%). The MIB-1 LI ranged from 0.1% to 6.0%, and 5 cases (33%) had an MIB-1 LI >2%. The correlation between histologic atypia and MIB-1 LI was poor, with only 1 tumor having both atypia and MIB-1 LI >2%. Clinical follow-up ranged from 13 to 255 months postoperatively (mean, 68 months). Although most patients were alive and well at last follow-up, three developed symptomatic recurrence and one died as a result of increased tumor growth. The tumors from all 4 patients with a poor outcome had MIB-1 LI >2%, but only 1 had histologic atypia.

CONCLUSIONS

The proliferation potential of central neurocytoma is a useful predictor of clinical outcome, whereas histologic atypia alone is not prognostically significant. It would be appropriate to recognize a subgroup of central neurocytomas with elevated proliferation potential as WHO Grade 2 lesions. The terms "atypical" and "anaplastic" are not appropriate to describe these lesions, as they imply a certain histologic appearance. The most accurate designation would be "proliferating neurocytoma."

Central neurocytoma: morphological, flow cytometric, polymerase chain reaction, fluorescence in situ hybridization, and karyotypic analyses. Case report

The results of cytogenetic and molecular genetic analysis of a central neurocytoma are presented. Central neurocytomas are intriguing neoplasms that exhibit primarily neuronal, but also glial characteristics, which indicate an origin from a pluripotential neuroglial precursor. The authors describe an intraventricular neurocytoma in an 11-year-old boy that showed anaplastic features with widespread necrosis and mitoses, as well as extensive calcification and foci that exhibited marked neuronal differentiation with clusters of ganglion cells. Immunohistochemical examination showed prominent synaptophysin and neurofilament positivity and focal glial fibrillary acidic protein positivity. Electron microscopy revealed abundant neuritic processes with microtubules and dense core granules as well as mature ganglion cells. Flow cytometry studies revealed increased S (7.8%) and G2M (9.7%) phase components. Molecular and cytogenetic studies were undertaken to assess whether there were similarities to two other tumor types that exhibit neuronal differentiation, the neuroblastoma and medulloblastoma. Polymerase chain reaction and fluorescence in situ hybridization (FISH) analysis revealed no evidence of amplification of the MYCN oncogene or chromosome 1p deletion, which are common in neuroblastomas. Chromosomal analysis by G banding revealed a complex karyotype, with counts in the near-diploidy range (45-48). Two chromosomes 1 appeared normal on G banding and FISH analysis, with p58 signals present on the distal p arm of both chromosomes 1; however, three additional copies of distal 1q were present in rearrangements with 4 and 7. Although the histological findings indicate a kinship to the neuroblastoma and medulloblastoma, the central neurocytoma appears to have a different karyotypic profile, although more cases need to be assessed using molecular genetic analysis.

A study of proliferative markers in central neurocytoma

To gain a better insight into the biological behavior of central neurocytomas, various proliferative indices were studied in these tumors and correlated with the histological features as well as the clinical outcome. Twenty cases of neurocytoma were selected over a 16 year period (1980-1995), which accounted for 0.28% of all intracranial tumors reported at this centre. Treatment consisted of surgical resection (total 14, subtotal six) followed by radiotherapy. Except for five patients who died of surgical complications, the remaining 15 were all alive and well during the follow-up period, varying from six months to 72 months (average 32 months). Thirteen tumors showed benign histological characteristics (Group I) while seven showed mitoses + necrosis (Group II). The proliferative index was assessed in formalin-fixed paraffin-embedded tissue of 17 cases using the silver nucleolar organiser region (AgNOR) technique and immunohistochemical staining for proliferating cell nuclear antigen (PCNA-PC10 antibody) and Ki-67 antigen (MIB-1 monoclonal antibody). The AgNOR counts ranged from 1.2 to 2.6 (mean 1.9 +/- 0.4), PCNA labeling index (LI) from 0.1 to 5.5 (mean 2.5 +/- 1.8) and MIB-1 LI from 0.1 to 3 (mean 0.8 +/- 0.02). There was no significant difference in any of these parameter values between histological Groups I and II, except that MIB-1 LI tended to be higher in Group II tumors. Further, there was no significant correlation between these proliferative indices and the mitotic rate of the tumors as well as the survival of the patients. A longer follow-up will be required to determine the relationship between proliferative markers and outcome as well as to bring out any heterogeneity in their biological behavior. Since these are relatively rare tumors, multicentric pooling of data will be required to reach a definitive consensus regarding their biological aggressiveness and consequentially, the use of radiotherapy in their treatment. The present report is a contribution in this direction.

Papillary glioneuronal tumor: a new variant of mixed neuronal-glial neoplasm

We describe the clinicopathologic features of nine cases of a unique papillary glioneuronal tumor (PGNT) exhibiting astrocytic as well as extensive and varied neuronal differentiation. The four male and five female patients studied ranged in age from 11 to 52 years (mean 27.7 years). They either presented with mild neurologic symptoms or were asymptomatic. Magnetic resonance imaging showed demarcated cystic, 1.5-cm to 7-cm contrast-enhancing masses; five involved the temporal lobe, two the parietal, and two the frontal. All but one were totally resected. No recurrence was noted despite a follow-up period of 3 years. Two microscopic components were evident: 1) compact pseudopapillae composed of hyalinized vessels covered by a single layer of glial fibrillary acid protein (GFAP)-positive astrocytes and 2) synaptophysin-positive neuronal cells of varying size, including neurocytes, ganglioid cells, and ganglion cells within neuropil. Immunostains for chromogranin-A were negative, as was in situ hybridization for chromogranin-A mRNA. Ultrastructurally, neuronal cells featured microtubule-containing processes and aberrant synaptic terminals, but dense core granules were rare. Overall, cellularity was moderate and atypia was minimal. No mitotic activity or necrosis was noted. The proportions of the two components varied, but essential morphologic findings were identical in all cases. In that the clinical, radiographic, and morphologic characteristics of PGNT are distinctive, it appears to represent a previously undescribed form of mixed neuronal-glial tumor of the central nervous system.