Neuroradiology of central neurocytoma

Central neurocytoma-positive and differential diagnosis: An example through a case report

Central neurocytoma is a rare intraventricular tumor, occurring typically in the lateral ventricle of young adults. It is considered as a neuronal-glial benign tumor with favorable prognosis. Imaging is a cornerstone allowing the accurate preoperative diagnosis on the basis of several characteristic features. We report the case of a 31-year-old man who has been complaining of progressive headaches and in whom brain magnetic resonance imaging revealed a central neurocytoma. We remind then, through a literature review, the main criteria to set the diagnosis of this tumor and rule out the other possible diagnoses.

Differential Diagnosis of Central Neurocytoma: Two Cases

Central neurocytoma are rare primary brain tumors of the young and middle-aged adult, typically located in the lateral ventricles. Diagnosis has historically been difficult due to histomorphologic similarities to oligodendroglioma and ependymal tumors and remains a challenge even today. We present two cases of intraventricular central neurocytoma in which careful consideration of the clinical and radiological findings led to reevaluation of the preliminary histological interpretation, highlighting the importance of a meticulous differential diagnosis.

Long-term follow-up of lateral ventricular central neurocytoma treated with subtotal resection followed by concurrent chemoradiotherapy and add on chemotherapy - Case report from a Tertiary Kenyan Cancer Hospital

Background:

Central neurocytomas are rare, mostly benign neuroectodermal tumors of the central nervous system typically located within the lateral and third ventricles of cerebrum. No consensus guidelines for the management of central neurocytoma available due to the rarity of the disease.

Case Description:

We report a case of right ventricular central neurocytoma of a 28-year-old lady who had a subtotal resection and ventriculoperitoneal shunting. Postoperatively, she was treated with concomitant chemotherapy with oral temozolomide and radiotherapy, followed by add-on chemotherapy with same drug. Imaging, microscopic evaluation, treatment modalities, and outcome of treatment are presented.

Conclusion:

Subtotal resection of tumor through transcallosal approach and ventriculoperitoneal shunt was performed. Imaging done 2 weeks postsurgery confirmed residual disease. Concurrent chemoradiotherapy (54 Gy in 30 fractions +Oral Temozolomide 75 mg/m² daily), followed by six cycles of 5-day chemotherapy with temozolomide (150 mg/m² in Cycle 1, and 175 mg/m² in subsequent cycles) at 28-day intervals, was given. No major toxicities encountered. Follow-up scan after 36 months showed complete remission.

Stereotactic radiosurgery for hypervascular intracranial tumors

OBJECTIVE

To evaluate the safety and efficacy of SRS treatment of central neurocytomas (CNCs), cavernous sinus hemangiomas (CSHs), and glomus tumors (GTs); and to compare upfront stereotactic radiosurgery (SRS) and adjuvant SRS in the treatment of these hypervascular tumors.

METHODS

This was a retrospective review of consecutive CNCs, CSHs, and GTs treated with SRS between 1993 and 2017. Tumor response was categorized based on volumetric analysis on magnetic resonance imaging: (1) tumor regression [> 10% decrease in tumor volume (TV)]; (2) stable tumor (≤ 10% change in TV); or (3) tumor progression (> 10% increase in TV).

RESULTS

Sixty hypervascular tumors (CNC: 28; CSH: 16; GT: 16) underwent SRS between 1993 and 2017. Margin doses were 13 Gy, 12 Gy, and 14 Gy for CNCs, CSHs, and GTs, respectively. Tumor regression was observed in 54 tumors (90%) with initial SRS after a median follow-up of 82 months. Relative reductions in TVs for CNCs were 38%, 52%, and 73% at 12, 24, and 48 months, respectively. Relative reductions in TVs for CSHs were 51%, 68%, and 88% at 12, 24, and 48 months, respectively. Relative reductions in TVs for GTs were 22%, 31%, and 47% at 12, 24, and 48 months, respectively. Upfront SRS was performed in 26 patients (43%). No difference in relative TV reductions were found between upfront and adjuvant SRS. Adverse radiation effects were observed in five patients. No mortality was encountered.

CONCLUSION

SRS for hypervascular tumors is associated with high rates of tumor regression with low risk of complications. No significant difference in rates of relative TV reduction were found between upfront and adjuvant SRS. Hence, upfront SRS may be considered in select patients.

Central Neurocytoma: A Review of Clinical Management and Histopathologic Features

Central neurocytoma (CN) is a rare, benign brain tumor often located in the lateral ventricles. CN may cause obstructive hydrocephalus and manifest as signs of increased intracranial pressure. The goal of treatment for CN is a gross total resection (GTR), which often yields excellent prognosis with a very high rate of tumor control and survival. Adjuvant radiosurgery and radiotherapy may be considered to improve tumor control when GTR cannot be achieved. Chemotherapy is also not considered a primary treatment, but has been used as a salvage therapy. The radiological features of CN are indistinguishable from those of other brain tumors; therefore, many histological markers, such as synaptophysin, can be very useful for diagnosing CNs. Furthermore, the MIB-1 Labeling Index seems to be correlated with the prognosis of CN. We also discuss oncogenes associated with these elusive tumors. Further studies may improve our ability to accurately diagnose CNs and to design the optimal treatment regimens for patients with CNs.

MR Appearance of Central Neurocytoma

To provide a detailed description of the MR appearances of central neurocytoma, MR images of 13 patients with central neurocytoma were retrospectively reviewed and compared with CT examinations. The histology was confirmed by ultrastructural and immunohistochemical studies. In 12 patients the tumors were histologically benign and located in the anterior part of the lateral ventricle, 6 of which extended to the 3rd ventricle. There was one case of a histologically malignant variant involving the thalamus and lateral ventricle. The tumors were primarily solid, but contained cysts (85%, 11/13), calcifications (69%, 9/13), and signal void from tumor vessels (62%, 8/13), frequently producing heterogeneous signal intensity on both T1- and T2-weighted images. Most of the solid portion appeared isointense or slightly hyperintense relative to the cerebral cortex on all MR pulse sequences. Calcifications were iso- or hypointense on MR, making them difficult to characterize with MR alone. Intratumoral hemorrhage was seen in 2 patients on MR but not on CT. Contrast enhancement was variable in degree and pattern. Coronal and sagittal MR images were valuable in evaluating the tumor extent and origin site, and in planning the surgical approach. It is concluded that MR imaging appears to be more useful than CT in the overall evaluation of central neurocytoma, even though calcification is better characterized with CT.

Intraventricular Central Neurocytoma

A case of central neurocytoma treated surgically is described. The authors review the literature. Emphasis is placed on radiological and pathological features not previously described. In particular, the intra-operative ultrasound appearance is described. The role of adjunctive radiotherapy is also discussed.

The management of incidental central neurocytoma

This article elucidates the role of stereotactic radiosurgery for the management of central neurocytoma. This rare intraventricular tumor is usually benign and is best treated with surgical excision if the tumor is large and symptomatic. However, some distinctive neuroimaging features are found in this tumor that help to identify the tumor based on detailed MRI and computed tomography examinations. The cumulative experience shows that single-session radiosurgery using Gamma Knife radiosurgery is an effective and safe alternative treatment of incidental central neurocytoma. After radiosurgery, a serial MRI examination performed every 6 months for long-term follow-up is necessary to monitor radiosurgical response of the tumor.

Treatment strategies for huge central neurocytomas

Central neurocytomas (CNs), initially asymptomatic, sometimes become huge before detection. We described and analyzed the clinical, radiological, operational and outcome data of 13 cases of huge intraventricular CNs, and discussed the treatment strategies in this study. All huge CNs (n=13) in our study were located in bilateral lateral ventricle with diameter ≥5.0 cm and had a broad-based attachment to at least one side of the ventricle wall. All patients received craniotomy to remove the tumor through transcallosal or transcortical approach and CNs were of typical histologic and immunohistochemical features. Adjuvant therapies including conventional radiation therapy (RT) or gamma knife radiosurgery (GKRS) were also performed postoperatively. Transcallosal and transcortical approaches were used in 8 and 5 patients, respectively. Two patients died within one month after operation and 3 patients with gross total resection (GTR) were additionally given a decompressive craniectomy (DC) and/or ventriculoperitoneal shunt (VPS) as the salvage therapy. Six patients received GTR(+RT) and 7 patients received subtotal resection (STR)(+GKRS). Eight patients suffered serious complications such as hydrocephalus, paralysis and seizure after operation, and patients who underwent GTR showed worse functional outcome [less Karnofsky performance scale (KPS) scores] than those having STR(+GKRS) during the follow-up period. The clinical outcome of huge CNs seemed not to be favorable as that described in previous reports. Surgical resection for huge CNs should be meticulously considered to guarantee the maximum safety. Better results were achieved in STR(+GKRS) compared with GTR(+RT) for huge CNs, suggesting that STR(+GKRS) may be a better treatment choice. The recurrent or residual tumor can be treated with GKRS effectively.

A case of intraventricular primary central nervous system lymphoma

We report a case of primary central nervous system lymphoma presenting as multiple intraventricular masses in an immunocompetent 68 year old man with severe headache and unsteady gait. The diagnosis was obtained by analysis of the cerebrospinal fluid and subsequent surgical biopsy. This is an unusual appearance for primary central nervous lymphoma, with the majority of the cases presenting as solitary masses.

MR imaging of cerebral extraventricular neurocytoma: a report of 9 cases

Extraventricular neurocytoma is a rare entity, most frequently occurring in brain parenchyma outside the ventricular system. The purpose of this study was to characterize the MR imaging findings in a series of 9 patients with EVN verified by results of pathologic examination. All 9 EVNs were solitary and intracranially located. Eight lesions were well demarcated, and 3 showed intratumoral hemorrhage. The solid parts of 7 tumors were primarily isointense on T1-weighted images and heterogeneously enhanced on T1WI with contrast. Although cerebral EVNs can present a wide spectrum of appearances on MR, the imaging patterns appear to vary according to anatomic location and cellularity. Lesions in frontal or parietal lobes often present as well-demarcated large masses with cystic degeneration, hemorrhage, mild-to-moderate edema, and inhomogeneous enhancement. Moreover, the general isointensity of the solid parts of EVN on T1WI may be of some specificity.

[Central neurocytoma: Study of 32 cases and review of the literature]

Central neurocytoma is a rare benign neoplasm of the central nervous system. The intraventricular location close to the Monro foramina and the attachment to the septum pellucidum are characteristic for the diagnosis. However, atypical appearances may be encountered and confused with other neoplasms. The authors report the radiological findings of 32 surgically treated and pathologically confirmed neurocytomas.

Central neurocytoma presenting with massive hemorrhage leading to coma--case report

A 21-year-old man presented with a hemorrhagic central neurocytoma manifesting as acute onset of disturbance of consciousness and right hemiparesis. Computed tomography (CT) demonstrated a tumor in the left lateral ventricle during the course of evaluation for mental alteration 12 days before onset, but the tumor was left untreated because the patient refused to visit a neurosurgical institution. CT on admission revealed a large mass lesion located in the body of the lateral ventricle associated with massive intratumoral and intraventricular hemorrhage. He underwent emergent surgery for evacuation of the tumor with hematoma, and his neurological symptoms gradually recovered after surgery. The present case highlights the possibility of rapid deterioration of symptoms by massive hemorrhage from central neurocytoma. Surgical intervention should thoroughly be considered, if intratumoral hemorrhage is present, as hemorrhage from the central neurocytoma may lead to serious neurological complications.

Gamma knife radiosurgery for central neurocytoma: primary and secondary treatment

BACKGROUND

Little is known about long-term results of gamma knife (GK) stereotactic radiosurgery (SRS) as a primary or a secondary postoperative therapy for central neurocytomas (CNs). The authors retrospectively reviewed long-term outcomes of 13 patients with CN treated with GK SRS.

METHODS

Thirteen patients were treated with GK SRS as a primary (6 patients) or a secondary postoperative therapy (7 patients). Follow-up clinical status and brain magnetic resonance imaging (MRI) were thoroughly analyzed. The functional status of patients was assessed with the Karnofsky Performance Scale during follow-up.

RESULTS

The median follow-up period for clinical status and imaging studies was 61 months (range, 6 months to 96 months). Tumors decreased in 5 patients who received GK SRS as a primary treatment. However, the tumor recurred in 2 patients treated with a secondary GK SRS after surgery from the residual tumor bed that was not covered by the GK SRS. Parenchymal changes and secondary malignancies were not found in follow-up MRIs of all 13 patients. The Karnofsky Performance Scale score of all patients, except for 1 patient who suffered from an unrelated anteriorly communicating arterial aneurysmal rupture, did not change after GK SRS.

CONCLUSIONS

GK SRS may be useful as a primary or a secondary postoperative therapy for the treatment of CN. However, more attention should be paid to residual or recurrent CN during treatment, and regular long-term follow-up MRI should be mandatory to validate the procedure.

Central neurocytoma: a clinical, radiological and pathological study of nine cases

PURPOSE

Central neurocytoma is a rare intraventricular brain tumor that affects young adults and presents with increased intracranial pressure secondary to obstructive hydrocephalus. Typically, it has a favorable prognosis after adequate surgical intervention, but in some cases the clinical course is more aggressive. In this report, we describe the diagnosis and treatment of central neurocytoma in a series of patients at our institution.

PATIENTS AND METHODS

Our series of nine patients (M:F=2:7, mean age, 28.2 years) with ventricular tumors showed typical radiological, histologic and immunohistochemical features of central neurocytoma. Most patients received craniotomy with removal of the tumor through transcallosal or transcortical approach. The surgical and histopathologic data of these patients were reviewed and analyzed.

RESULTS

The prognosis is generally favorable. Although most patients were alive and well at the last follow-up, two developed recurrence. Typical histologic features of recurrent neurocytoma include high proliferative activity (MIB-1 labeling index: 2.0-6.8%), prominent vascular proliferation and remarkable synaptophysin expression. Two patients (non-recurrent) died during follow-up due to sepsis or central failure. The MIB-1 labeling indices were as high as 2.2-5.4% for these two patients.

CONCLUSION

Although central neurocytoma is generally a benign neoplasm, some variant forms of recurrence are also present. Complete resection provides favorable long-term prognosis in most cases. Recurrent tumors are often local and the patients seem to recover well after a second resection followed by radiotherapy. Histologic features such as tumor proliferation (MIB-1 labeling index), vascular proliferation, and synaptophysin expression are often prominent in the recurrent tumor. We recommend that these histologic features be considered for tumor recurrence during treatment and follow-up of these patients.

Central neurocytoma: clinical, pathological and neuroradiological findings

AIM

To evaluate the clinical, pathological and neuroradiological features of intraventricular central neurocytoma in six patients.

MATERIALS AND METHODS

Six patients were imaged using non-enhanced and contrast-enhanced magnetic resonance imaging (MRI); three of them were also examined using non-enhanced computed tomography (CT). Two radiologists read the images retrospectively. The imaging data were studied with regard to location, size, margin, signal intensity, enhancement characteristics and presence of calcifications. Clinical data (i.e. presenting signs and symptoms, physical findings and medical histories) were collected and histopathological and immunohistochemical studies were performed by two pathologists.

RESULTS

All lesions were located in the lateral ventricles. Three tumors were confined to the left side, one to the right side and two cases involved both lateral ventricles. The growth of central neurocytoma was of close spatial relation to the septum pellucidum. On MRI, most of the cases showed a heterogeneous hypointensity on T1-weighted images and hyperintensity on T2-weighted images or FLAIR with a well-defined margin. The presence of cystic components, necroses and calcifications caused these internal heterogeneities. After intravenous administration of gadolinium (Gd-DTPA) all tumours showed a heterogeneous enhancement. CT provided additional information by distinguishing intratumoural calcifications in all three evaluated cases. Immunohistochemical analysis showed positive synaptophysin staining in all cases and positive neuron-specific enolase staining in four cases. In three cases a small proportion of the tumour cells could be labelled with antibodies to glial fibrillary acid protein (GFAP).

CONCLUSION

Central neurocytoma should be considered when the following conditions occur: young patients with lesions in the lateral ventricle, which contain calcifications and show some enhancement. This is especially applicable for tumours involving both lateral ventricles with symmetrical growth around the centre of septum pellucidum or for unilateral ventricular tumors with a wide base attachment to the septum pellucidum.

Well-differentiated neurocytoma: what is the best available treatment?

Most neurocytomas are well differentiated, being associated with better long-term survival than the more aggressive atypical lesions. Atypical neurocytomas are characterized by an MIB-1 labeling index >3% or atypical histologic features. This analysis focuses on well differentiated neurocytomas in order to define the optimal treatment. A case with a follow-up of 132 months is presented. The patient developed two recurrences two and four years after first surgery, each showing an increasing proliferation activity. Furthermore, all published well-differentiated neurocytoma cases were reviewed for surgery, radiotherapy, and prognosis. Additional relevant data were obtained from the authors. Complete resection (CTR), complete resection plus radiotherapy (CTR + RT), incomplete resection (ITR), and incomplete resection plus radiotherapy (ITR + RT) were compared for outcome by using the Kaplan-Meier method and the log-rank test. Data were complete in 301 patients (CTR, 108; CTR + RT, 27; ITR, 81; ITR + RT, 85). Local control and survival were better after CTR than after ITR (P < 0.0001 and P = 0.0085, respectively). Radiotherapy improved local control after ITR (P < 0.0001) and after CTR (P = 0.0474), but not survival (P = 0.17 and P = 1.0, respectively). In the ITR + RT group, doses < or =54 Gy (n = 33) and >54 Gy (n = 32) were not significantly different for local control (P = 0.88) and survival (P = 0.95). The data demonstrated CTR to be superior to ITR for local control and survival. After CTR and ITR, radiotherapy improved local control, but not survival. A radiation dose of 54 Gy appeared sufficient. Application of postoperative radiotherapy should be decided individually, taking into account the risk of local failure, the need for another craniotomy, and potential radiation toxicity.

Recurrent central neurocytomas

BACKGROUND

Since the first description of Central neurocytomas (CNs) as a benign tumor entity in 1982, there has been great enthusiasm regarding the benign course and the curative surgical approach to this disease. The current study was performed to investigate the frequency of disease recurrence during long-term follow-up.

METHODS

A retrospective analysis of the medical files with emphasis on clinicoradiologic findings and histologic and immunohistochemical features was performed.

RESULTS

Between 1985-2003. surgical resection was performed in 14 patients with CNs ages 16-43 years (7 were female and 7 were male). Two patients (14%) died postoperatively and one patient had a malignant disease course (7%). In the remaining 11 patients, one patient with an incompletely resected CN had disease progression after 37 months but at the time of last follow-up had had stable disease for 10 years. In addition, the authors reported 5 patients with disease recurrence occurring at a median of 67 months after surgery (range, 51-79 months after surgery), all of which occurred after complete surgical resection was performed. The observation period for the remaining 5 patients was short (median of 34 months [range, 5-44 months]). Extensive histologic and immunohistochemical workup did not identify any significant prognostic parameters. The MIB-1 proliferation index ranged from 0.8-11% (median of 4.6%), but was reported to be 46.8% in the malignant transformed tumor. All patients with disease recurrence responded well to different forms of focal radiation therapy (gamma knife radiosurgery in three patients and interstitial irradiation in one patient) and for one patient with a recently detected recurrence, gamma knife radiosurgery was planned.

CONCLUSIONS

CNs appear to have a higher tendency to recur during long-term follow-up than previously reported, even after complete resection. Therefore, periodic neuroradiologic follow-up examinations should be considered mandatory in all patients, even after several years.

Central neurocytoma: a clinicopathological and neuroradiological study

Central neurocytoma (CNC) is an uncommon benign tumor of the central nervous system (CNS) occurring in adults and is more likely to be located in the region of the foramina of Monra. Few studies have described the neuroradiological features of CNC, and most are single case reports. Our aim was to analyze the clinicopathological and neuroradiological characteristics of CNC. We retrospectively studied the preoperative CT (n=2) and MRI (n=5) of three men and two women (mean age 45 years, ranging from 30 to 63 years) with pathologically proven CNC. The tumors were primarily located in the region of the foramina of Monra. Two of them occupied the lateral ventricle, appearing to be attached to the septum pellucidum, and the other three tumors arose from the septum pellucidum and extended into the lateral ventricles. The tumors were of mixed density with cystic features and patchy or fine calcification on noncontrast CT scans, and they were of low or isointense signal on T1- and heterogeneously hyperintense signal on T2- and FLAIR weighted images. Contrast enhancement varied greatly from very slight to intense. Immunohistochemical staining showed a positive reaction for synaptophysin (Syn), neuro-specific enclase (NSE), neurofilament protein (NF) in the tumor cells and glial fibrillary acid protein (GFAP) in the fibrillar zones. CNC should be taken into consideration first if a tumor arises from the region of the foramina of Monra with CNC neuroradiological characteristics and the patient is an adult.

Central neurocytoma: a review

Central neurocytomas are rare intraventricular neoplasms of the central nervous system, compromising 0.25-0.5% of brain tumors. The diagnosis and management of these tumors remains controversial since most clinical series are small. Typically, patients with central neurocytomas have a favorable prognosis, but in some cases the clinical course is more aggressive. Although histological features of anaplasia do not predict biologic behavior, proliferation markers including MIB-1 might be more useful in predicting relapse. The most important therapeutic modality is surgery, and a safe maximal resection confers the best long-term outcome. In cases of a subtotal resection,'standard external beam radiation can be added or radiation can be delayed until tumor progression occurs. Smaller residual tumor volumes or recurrences can be treated with more conformal radiation or focused radiosurgery. Re-operation for recurrence should be considered if the procedure can be safely performed. Chemotherapy may be useful for recurrent central neurocytomas that cannot be resected and have been radiated, although long-term responses have not been reported for chemotherapy. Overall, this paper reviews the findings of the larger studies and highlights some of the important case reports that contribute to the current management of central neurocytomas.

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.

Tratamiento del neurocitoma central. Experiencia en nuestro centro

Central neurocytomas are classically considered as a rare, intraventricular benign tumours with neuronal differentiation derived from precursor cells of subventricular matrix. However some patients with neoplasms with histologic atypia and elevated proliferation potential may have a poor outcome. Treatment of choice is complete surgical excision. Adjuvant therapy is reserved for patients with residual or recurrent lesions including reoperation, radiotherapy or chemotherapy. We review our experience with the treatment of this neoplasm. Five patients with an intraventricular mass studied with magnetic resonance imaging underwent craniotomy for tumour resection. All cases were reviewed retrospectively. Histopathological analysis confirmed central neurocytoma in all cases. Proliferation index was assessed by Ki-67 immunohistochemistry. Complete radiological tumor resection through transcortical approach was achieved in all except one patient. In this case adjuvant therapy with radiosurgery was given with important reduction in tumor size. All the tumours had a proliferation index below 2% except one with 5%. Follow-up in four patients ranged from 12 to 36 months. There were no tumour recurrences in this period. Complete surgical excision of central neurocytoma provides better local control and survival compared with other treatments. Radiosurgery as adjuvant therapy in incomplete resections may eliminate the need of reoperation and avoid long-term side effects from conventional radiotherapy.

From the archives of the AFIP. Cerebral intraventricular neoplasms: radiologic-pathologic correlation

Intraventricular neoplasms are readily seen on cross-sectional images, but the myriad possibilities may make a focused differential diagnosis elusive. Consideration of the tissue within and composing the ventricular lining and the clinical findings provide the means to limit the differential diagnosis when analyzing an intraventricular mass on an imaging study. Ependymomas are typically calcified, are more common in children, are more common in the fourth ventricle, and show intense enhancement on contrast-enhanced images. Subependymomas and central neurocytomas have an affinity for the anterior portion of the lateral ventricle, and both commonly demonstrate a heterogeneous cystic appearance on cross-sectional images. Subependymomas are more common in older adults, whereas central neurocytomas are more common before 40 years of age. Subependymal giant cell astrocytomas always lie near the foramen of Monro and are characterized by frequent calcification, intense enhancement on contrast-enhanced studies, and the presence of other stigmata seen in tuberous sclerosis. When a mass is centered on the choroid plexus, a highly vascular tumor-either choroid plexus papilloma, choroid plexus carcinoma, meningioma, or metastasis-should be suspected. The characteristic heavily lobulated appearance of a choroid plexus tumor favors this diagnosis over other possibilities, although it is not always possible to distinguish between the more common benign form, the choroid plexus papilloma, and the less common malignant counterpart, the choroid plexus carcinoma. By using clinical, demographic, and imaging findings, one can significantly limit the differential diagnosis for many of the most common intraventricular neoplasms.

Neuronal tumors of the central nervous system: radiologic findings and pathologic correlation

Pure neuronal and mixed neuronal-glial tumors of the central nervous system are uncommon but fascinating because they are less aggressive than the more common glial tumors and their prognosis is excellent. Neurologic manifestations are varied and include seizures, symptoms of increased intracranial pressure, and neurologic deficits according to tumor location. Many neuronal tumors of the central nervous system demonstrate characteristic radiologic findings. At magnetic resonance (MR) imaging, gangliocytomas demonstrate low signal intensity on T1-weighted images, high signal intensity on T2-weighted images, and frequent enhancement on gadolinium-enhanced T1-weighted images. Characteristic MR imaging findings of Lhermitte-Duclos disease are a nonenhancing mass in a cerebellar hemisphere with a striated pattern. Central neurocytomas are typically located in the lateral ventricles near the foramen of Monro with a characteristic attachment to the septum pellucidum. Ganglioneurocytoma is a rare variant of central neurocytoma that is characterized by differentiation toward ganglion cells. In ganglioglioma, a well-defined cystic mass with a solid mural nodule is typically seen. Extension of enhancement to the leptomeninges is characteristic of desmoplastic infantile ganglioglioma and correlates with the firm dural attachment of the solid component. Dysembryoplastic neuroepithelial tumor has a well-demarcated, multilobulated or gyriform appearance.

Central Neurocytoma with Craniospinal Dissemination

We report a case of central neurocytoma that manifested tumor recurrence with craniospinal dissemination. Imaging studies before surgery showed a markedly enhanced tumor with small cysts and calcification, which invaded the adjacent brain parenchyma, located in the posterior horn of the right lateral ventricle. Proton MR spectroscopy showed markedly elevated choline and lactate peaks with a strongly diminished N-acetylaspartate peak. Two years after neurosurgical intervention, the tumor showed multiple craniospinal dissemination in the middle cranial fossa and the intradural extramedullary space of the spine.

Gamma knife radiosurgery of recurrent central neurocytomas: a preliminary report

OBJECTIVES

A series of three recurrent central neurocytomas treated by gamma knife radiosurgery (GKRS), which were initially totally resected, are described. Up to now, no reports exist on this treatment modality for this rare tumour entity.

METHODS

Three male patients, aged between 20 and 25 years, presented with large intraventricular tumours. Total tumour removal was achieved by a single surgical procedure (one patient) or two operations (two patients). Neuropathological investigation showed a central neurocytoma, immunohistochemically all three tumours expressed a neuronal antigenic profile typical for neurocytomas, and the MIB-1 proliferation index ranged from 2.4% to 8.7%. Each patient experienced a tumour recurrence after 5 to 6 years. The recurrence was multifocal in two and a singular tumour mass in one patient. Gamma knife radiosurgery was performed. The tumours were enclosed within the 30% to 60% isodoseline, and delivered a tumour marginal dose of 9.6 to 16 Gy. During the follow up period, the patients were tested clinically and the volume of the tumours was measured on MRI.

RESULTS

Within follow up periods of 1 to 5 years, control MRI showed a significant decrease of the tumour mass in all cases. None of the patients developed new neurological symptoms after GKRS. Two patients returned to work in their previous employment, whereas one patient remained permanently disabled due to a pre-existing visual impairment and abducens palsy.

CONCLUSION

GKRS proved to be a useful tool in the treatment of recurrent central neurocytomas. Tumour control and even tumour shrinkage can be achieved with a single procedure and a low risk of morbidity.

Intraventricular mass lesions of the brain

Intraventricular tumours represent a diverse group of lesions, some of them infrequent, with a wide variety of radiological features. Determination of their precise aetiology or origin can be difficult. Nevertheless, considering patient's age, location within the ventricles, and some specific radiological features, the radiologist should be able to narrow down the differential diagnosis. This paper reviews the characteristic radiological appearances of the diverse intraventricular lesions emphasising its differential diagnosis.

Central neurocytoma of the fourth ventricle. Case report

The authors report on a 17-year-old boy who suffered from slowly progressive and long-standing symptoms of ataxia, neck pain, and headache. Computerized tomography (CT) and magnetic resonance (MR) imaging revealed a tumor arising from the floor of the fourth ventricle that resulted in a moderate hydrocephalus. A partial resection was performed. Histological and immunohistological findings led to the diagnosis of an atypical central neurocytoma of the fourth ventricle. The imaging features on CT scanning, MR imaging, and proton MR spectroscopy studies, the clinical picture, and the prognosis of this very unusual tumor are discussed. Three cases of neurocytomas in the posterior fossa have been described to date; however, in all three cases some atypical aspects were present. In the present case, with the exception of the very unusual location, both imaging findings and clinical history perfectly met the definition of this rare tumor.

Magnetic resonance features of the enigmatic oligodendroglioma

RATIONALE AND OBJECTIVES

The authors characterize magnetic resonance (MR) features of oligodendroglioma that permit diagnosis. These features may be used to guide MR stereotactic biopsies.

METHODS

Fifteen patients with mixed oligodendroglioma and four with pure oligodendroglioma were studied on a 1.5-tesla MR unit with contrast and also by computed tomography (CT). All patients had their diagnosis confirmed by light and electron microscopy, and by immunohistochemical staining.

RESULTS

The most characteristic finding was a honeycomb tumor matrix (4 of 19) in oligodendroglioma. The most common finding was an amorphous pattern (12 of 19) and the least common was a large cystic pattern (3 of 19). Contrast enhancement most commonly was minimal and dot-like or lacy in appearance (11 of 19), or absent (5 of 19). Calcification was present in the majority (11 of 19).

CONCLUSIONS

The honeycomb and stippled amorphous patterns reflect the cytoarchitecture of oligodendroglioma and were the most characteristic MR features. The amorphous pattern was the most commonly encountered pattern. There was a wider range of imaging findings on MR compared with CT; the flocculent calcification on CT was typical, but it was not always detected on MR. Including these characteristic areas that appear along the path of the stereotactic biopsy may ensure a correct diagnosis of oligodendroglioma because it most often is seen with another tumor, usually of the astrocytic family. Identifying the oligodendrogliomatous portion of the tumor will influence the therapy. No differences could be found in the MR appearance or biologic behavior of pure versus mixed oligodendrogliomas.

Intraventricular neurocytoma

Intraventricular neurocytoma is a rare cerebral tumour which is usually associated with a good prognosis. It has imaging features which help differentiate it from other cerebral tumours. We report three cases including the first to originate from the pineal gland. The report emphasizes the radiological appearance and reviews the literature.

Blood flow and metabolism of central neurocytoma: a positron emission tomography study

BACKGROUND

New World Health Organization classifications have categorized central neurocytomas as neuronal tumors. The differential diagnosis between central neurocytomas and other tumors is important for selection of the optimal therapy modality for the management of intraventricular tumors. To characterize the pathophysiology and proliferating activity of central neurocytoma accurately, cerebral blood flow and metabolism in five patients with central neurocytoma were studied using positron emission tomography (PET).

METHODS

Tracers used for the present study included C15O2, C15O, 15O2, and 18F-fluorodeoxyglucose (FDG). Regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), oxygen extraction fraction (rOEF), cerebral metabolic rate of oxygen (rCMRO2), and cerebral metabolic rate of glucose (rCMRGl) were quantitatively analyzed in tumor lesions and the contralateral gray matter. Four patients with central neurocytoma underwent a complete PET study, including all circulatory and metabolic parameters; one patient was studied with 11C-methyl-L-methionine and FDG tracers.

RESULTS

Tumor rCBF and rCBV were higher than comparable values in the contralateral gray matter in three of four patients. This high level of perfusion corresponds to angiographic findings that show intense tumor staining in tumors fed by perforated arteries. Tumor rOEF and rCMRO2 were significantly lower than corresponding values in the gray matter (rOEF, P < 0.01; rCMRO2, P < 0.05 by Student's t test). Tumor rCMRGl ranged from 2.68 to 6.26 mg/100 ml/minutes and did not exceed contralateral gray matter values in any of the five patients. Tumor rCMRGl was significantly lower (P < 0.02) than the gray matter rCMRGl. One tumor exhibited a relatively high value of rCMRGl (comparable to gray matter rCMRGl), and increased in size 4 months after partial resection. No other tumors appeared during postoperative follow-up periods that ranged from 4 to 135 months.

CONCLUSIONS

Circulation and metabolism parameters measured by PET offer insight into the biologic characteristics of central neurocytoma. Tumor rCMRGl may be an indicator of the proliferating activity in central neurocytoma.

Central neurocytomas of the cervical spinal cord. Report of two cases

Central neurocytoma is a neuronal neoplasm that occurs supratentorially in the lateral or third ventricles. The authors report the clinical, neuroradiological, and neuropathological features of two neurocytomas arising in the spinal cord of two men, aged 65 and 49 years. The patients presented with progressive neurological deficits referable to the cervical spinal cord. Magnetic resonance imaging revealed isodense intramedullary spinal cord tumors at the C3-4 level. Both tumors were initially misdiagnosed as gliomas. In Case 1 the correct diagnosis was made after electron microscopy revealed neuronal features. Immunostaining in Case 2 revealed that tumor cells were positive for synaptophysin and negative for glial fibrillary acidic protein, strongly indicating a neuronal tumor. It is suggested that this spinal cord neoplasm be included under the designation "central neurocytoma."

Central neurocytoma: a synopsis of clinical and histological features

The central neurocytoma is a supratentorial, often calcified brain tumour affecting young adults and is typically located in the lateral ventricles in the region of the foramen of Monro. Clinically, the tumour causes signs of increased intracranial pressure, visual and mental disturbances and, occasionally, pyramidal or endocrine symptoms. By light microscopy, the tumour is composed of small round cells in a delicate fibrillary matrix. Tumour cells consistently show features of neuronal differentiation by electron microscopy (synapses, dense-core vesicles, presynaptic clear vesicles, specialized synaptic junctions) and immunoreactivity for synaptophysin and other neuronal marker proteins. The tumour can be totally removed in nearly half of the cases. After incomplete surgical resection neurocytomas may recur but because of their low proliferation potential, radio- or chemotherapy are not generally recommended. Postoperative recurrence-free survival times of up to 19 years have been reported. Neurocytomas constitute nearly one half of supratentorial intraventricular tumours in adults but amount to less than 1% of all tumours of the central nervous system and its coverings.