Radiation therapy of well-differentiated neuroblastoma and central neurocytoma

[Central neurocytomas: long-term treatment outcomes]

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.

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.

Clinical outcome and prognostic factors for central neurocytoma: twenty year institutional experience

Central neurocytomas are uncommon intraventricular neoplasms whose optimal management remains controversial due to their rarity. We assessed outcomes for a historical cohort of neurocytoma patients and evaluated effects of tumor atypia, size, resection extent, and adjuvant radiotherapy. Progression-free survival (PFS) was measured by Kaplan-Meier and Cox proportional hazards methods. A total of 28 patients (15 males, 13 females) were treated between 1995 and 2014, with a median age at diagnosis of 26 years (range 5-61). Median follow-up was 62.2 months and 3 patients were lost to follow-up postoperatively. Thirteen patients experienced recurrent/progressive disease and 2-year PFS was 75% (95% CI 53-88%). Two-year PFS was 48% for MIB-1 labeling >4% versus 90% for ≤4% (HR 5.4, CI 2.2-27.8, p = 0.0026). Nine patients (32%) had gross total resections (GTR) and 19 (68%) had subtotal resections (STR). PFS for >80% resection was 83 versus 67% for ≤80% resection (HR 0.67, CI 0.23-2.0, p = 0.47). Three STR patients (16%) received adjuvant radiation which significantly improved overall PFS (p = 0.049). Estimated 5-year PFS was 67% for STR with radiotherapy versus 53% for STR without radiotherapy. Salvage therapy regimens were diverse and resulted in stable disease for 54% of patients and additional progression for 38 %. Two patients with neuropathology-confirmed atypical neurocytomas died at 4.3 and 113.4 months after initial surgery. For central neurocytomas, MIB-1 labeling index >4% is predictive of poorer outcome and our data suggest that adjuvant radiotherapy after STR may improve PFS. Most patients requiring salvage therapy will be stabilized and multiple modalities can be effectively utilized.

Long-term outcomes of adjuvant radiotherapy after surgical resection of central neurocytoma

Background and purpose

The role of adjuvant radiotherapy for central neurocytomas (CNs) is not clear. Therefore, we aimed to examine the clinical outcomes of treating histologically confirmed CNs with adjuvant RT after surgical resection.

Material and methods

Sixty-three CN patients were retrospectively evaluated: 24 patients underwent gross total resection (GTR); 28, subtotal resection (STR); 9, partial resection (PR), and 2, biopsy (Bx). They underwent adjuvant RT after surgery (median dose, 54 Gy).

Results

The median follow-up was 69 months (15–129 months). The 5-year overall survival (OS) and 5-year progression-free survival (PFS) were 94.4% and 95% after GTR + RT, 96.4% and 100% after STR + RT, and 100% and 90.9% after PR + RT. Only three patients had tumor recurrence: at the primary site at 30 and 24 months in two GTR + PR patients, and dissemination to the spinal cord at 75 months in one STR + RT patient. Thirty-eight (63.3%) patients experienced late neurotoxicity (28, grade 1; 7, grade 2; 3, grade 3). Short-term memory impairment was the most common toxicity.

Conclusions

RT after incomplete resection (IR) led to OS and PFS comparable to those for GTR. Considering the excellent outcomes and limited late toxicity, adjuvant RT maybe a good option for CN patients who undergo IR.

Surgical management of intraventricular central neurocytoma: 92 cases

OBJECTIVE

To analyse the clinical characteristics of intraventricular central neurocytomas and gain a better understanding of the surgical management and treatment strategies.

METHODS

A total of 92 cases of intraventricular central neurocytomas with initial treatment using surgical resection were studied retrospectively.

RESULTS

Among 48 male and 44 female patients, 65 underwent gross total resection and 27 underwent subtotal resection. Transcortical or transcallosal approaches were performed, and there was no significant difference between the two approaches in terms of effects and complications. Tumours with calcification or adhesion had a significant lower gross total resection rate. Three patients died after surgery. During follow-up, 55 patients underwent postoperative radiotherapy and four patients had a recurrence of the tumour.

CONCLUSION

Central neurocytomas mostly occur in the lateral ventricle system near the foramen of Monro. Therefore, total resection is the best treatment. Two surgical approaches are possible as treatment. Calcifications or adhesions affect the gross total resection of the tumour. Radiation therapy or radiosurgery therapy can be chosen as a salvage treatment in case of recurrence.

Stereotactic radiosurgery for central neurocytoma: a quantitative systematic review

Central neurocytoma was originally described as a rare benign neuronal tumor. However, progression and local recurrences after surgery are well recognized. Stereotactic radiosurgery is another option for treatment of CN. In order to evaluate the efficacy of SRS, we performed a quantitative systematic review of the available data on SRS for CN. To identify eligible studies, systematic searches for all CNs treated with SRS were conducted in major scientific publication databases. English studies published prior to May 2011 were reviewed and summarized with reference to the inclusion and exclusion criteria. Tumor local control was analyzed. Heterogeneity and publication bias were assessed, and the summary control rate and 95%confidence interval (CI) were calculated from the raw data.Of 35 eligible studies, five with a total of 64 CNs were included in this quantitative analysis. Four studies reported a mean or median follow-up time of[60 months. The test of heterogeneity was non-significant among the included studies. Publication bias was observed as indicated by an asymmetric funnel plot. There was non-significance in Begg’s test and Egger’s test. The estimated cumulative rate of neuro-imaging tumor control was 91.1% (95%CI = 80.2–96.3%) at a mean follow-up of 59.3 months(range 6–140 months). The P-value was\0.0001 under a random-effect model. Sensitivity analysis showed a similar summary control rates (89.5–93.7%). Based on the summary local control rate of SRS for CN found in this quantitative analysis, we suggest that single session SRS is an effective and safe alternative therapy for recurrent or residual CN. However, the results of our analysis are limited by the predominance of case series studies due to scarcity of published research. Further randomized trials of CN patients via multicenter consortia should be considered for supplementing the weak points in our quantitative analysis.

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.

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.

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.

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.

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.

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.

The role of PCV chemotherapy in the treatment of central neurocytoma: illustration of a case and review of the literature

BACKGROUND

Most central neurocytomas follow a benign clinical course. However, more aggressive variants have been described requiring additional surgical resection, radiation, or chemotherapy. Chemotherapy has rarely been used as an adjuvant therapy for central neurocytomas.

METHODS

We report a case of a 20-year-old girl who underwent four subtotal resections, over the course of 3 years, for a large central neurocytoma that continued to progress. She was not a candidate for stereotactic radiosurgery, given the large tumor size. To avoid radiation injury in a young patient, she was treated with six cycles of chemotherapy including procarbazine, CCNU, and vincristine. Procarbazine was stopped after 2 cycles because of the development of a rash. Serial magnetic resonance imaging was used to follow treatment response.

RESULTS

Her tumor started to decrease in size after 2 cycles of chemotherapy and continued to shrink until it stabilized after 5 cycles of chemotherapy. A small area of residual tumor with minimal enhancement persisted along the left lateral ventricle and remained stable for at least 16 months after the completion of chemotherapy.

CONCLUSIONS

To our knowledge, this is only the fourth report describing the use of chemotherapy for progression of central neurocytomas as a treatment alternative to radiation therapy. The use of procarbazine, CCNU, and vincristine has not been previously described for the treatment of a central neurocytoma and presents an additional treatment option.

Two cases of atypical central neurocytomas

Central neurocytomas (CNs) are usually considered benign; however, some subsets of these tumors with histologic atypia and elevated proliferation potential have been reported to have a poor outcome. It has been proposed that those CNs exhibiting a MIB-1 labeling index (LI) greater than 2% and/or vascular proliferation be defined as atypical central neurocytoma (ACN). Two cases of ACN are reported here. Case 1 was a 13-year-old male who complained of headache. An MRI showed an enhancement of the tumor in the third ventricle and left lateral ventricle. The tumor was completely removed transcortically by a left frontotemporal craniotomy. The tumor showed anaplastic features, including microvascular proliferation, mitosis, and necrosis. The MIB-1 LI was 7.8%. The patient received 50Gy of focal irradiation. After 16 months of follow-up, no recurrence was observed. Case 2 was a 17-year-old female who presented with headache. An MRI showed an enhancement of the tumor in the right lateral ventricle. To preserve the internal cerebral vein, the tumor was partially removed by the transcingulate approach after a bifrontal craniotomy. Histologically, the tumor displayed the typical features of a CN. The MIB-1 LI was 7.0%. Complete remission was achieved through 50Gy of focal irradiation. After 15 months of follow-up, there was no recurrence. The differences in the histopathological findings in these two cases indicate the presence of a variety of histopathological features among ACNs.

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.

Linear accelerator radiosurgery for central neurocytoma: a case report

This study presents a case of central neurocytoma successfully treated with linear accelerator (LINAC)stereotactic radiosurgery. Originally, the tumor in the left lateral ventricle was removed by craniotomy, but a small residual mass was detected in follow-up magnetic resonance imagery 6 months after the operation. A further 6 months later, additional radiographic studies revealed that the residual mass had grown. LINAC radiosurgery was then performed, in which 1750 cGy doses were delivered at the 70% level with 3 isocenters (collimator size, 2 cm). The mass was completely absent over the duration of follow-up, including the final MR imagery examination 51 months after radiosurgery. LINAC radiosurgery is suggested to be a good treatment modality for residual or recurrent 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.

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.

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 with unusually intense FDG uptake: case report

Central neurocytoma is a benign neuronal tumor with a favorable prognosis. This tumor is typically characterized by decreased uptake of 18F-fluorodeoxy glucose (FDG) and any increased uptake of FDG in patients suffering from this tumor would be highly unusual. A case of central neurocytoma with an intense FDG uptake, combined with atypical histopathological features and a high proliferation index is reported in this paper. A 45-year-old male had a two months' history of right hemiweakness. Magnetic resonance (MR) imaging showed a large tumor in the right lateral ventricle. Positron emission tomography (PET) with FDG revealed high glucose metabolism in the tumor. The histological diagnosis was central neurocytoma with atypical features characterized by microvascular proliferation. The MIB-1 labeling index, ordinarily smaller than 2.0%, was 7.0%. Conventional radiotherapy, with a total dose of 50 Gy, was administered after the surgical treatment. The patient returned to his normal daily activities after the cessation of radiation therapy.

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.

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.

Chemotherapy in patients with recurrent and progressive central neurocytoma

BACKGROUND

Recurrent central neurocytoma is very rare and to the authors' knowledge data regarding its response to chemotherapy currently are not available.

METHODS

Three patients with progressive neurocytoma received chemotherapy after their informed consent was obtained. Disease recurred in two patients after surgery and radiotherapy and in one patient after surgery. The treatment regimen was comprised of etoposide, 40 mg/m(2)/day, for 4 days; cisplatin, 25 mg/m(2)/day, for 4 days; and cyclophosphamide, 1,000 mg/m(2), on Day 4; this cycle was repeated every 4 weeks.

RESULTS

Stabilization of disease was observed in 2 patients and complete remission was observed in 1 patient; at last follow-up, these responses had been maintained for 15 months, 18 months, and 36 months, respectively.

CONCLUSIONS

In this small series, this therapeutic regimen led to long term disease reduction, and merits further study.

Central neurocytoma: the role of radiation therapy and long term outcome

BACKGROUND

It has been suggested that the biologic behavior of central neurocytoma is indolent, although little is known regarding the role of radiation therapy and long term outcome. To clarify the role of radiation therapy and long term outcome, the authors retrospectively analyzed 15 cases of central neurocytoma.

METHODS

Clinical records and radiologic findings of 15 cases of central neurocytoma diagnosed at Seoul National University Hospital between January 1982 and February 1995 were carefully reviewed. The duration of follow-up was from 18-168 months (mean, 52 months); follow-up images were reviewed and the patient's Karnofsky performance scale (KPS) was assessed up to the time of last follow-up.

RESULTS

The age of the patients ranged from 15 to 60 years (mean, 25 years) and the male to female ratio was 11:4. Macroscopic total resection of the tumor was performed in seven patients, two of whom received fractionated radiation therapy. Subtotal removal of the tumor was performed in eight patients, five of whom received this same therapy. In 2 of the 5 patients who did not receive radiation therapy after macroscopic total resection, the tumors recurred 8 and 21 months after surgery, respectively; in contrast, recurrence was not detected in the 2 patients who received fractionated radiation therapy after macroscopic total resection. In all five patients who received fractionated radiation therapy after subtotal resection, the tumor shrank (n = 3) or disappeared (n = 2) during the postsurgical follow-up period ranging from 27-113 months; the tumor began to shrink from 6 months to 2 years after radiation. No change was found in the three patients who did not receive radiation therapy after subtotal resection. At the time of last follow-up, the KPS was greater than 90 in all patients except one who required assistance in his daily activities because of complications from radiation therapy.

CONCLUSIONS

It is suggested that even if the biologic behavior of a central neurocytoma is benign, radiation therapy appears to have an effect on tumor control. However, it should be carefully decided whether to use radiation therapy for a residual tumor because radiation can cause delayed complications and the clinical course of subtotally resected patients who do not receive radiation therapy is extremely benign.

Central neurocytoma: clinical features of 8 cases

The authors report 8 cases of central neurocytoma with a minimum follow-up of 3 years. Five patients were males and 3 females with average age of 21 years. All patients underwent surgical removal of tumor, and radiotherapy was delivered to 2 of the 3 patients in whom removal had been partial. At an average follow-up of 5 years, all patients are alive and none of them has presented signs of recurrence or progression of the disease. Some typical clinical and histological features of this tumor are pointed out.

Central neurocytoma occurring in the thalamus: CT and MRI findings

A case of central neurocytoma occurring in the thalamus, confirmed by electron microscopy and immunohistochemistry, is reported. Computed tomography demonstrated a hypodense mass with an irregular margin arising from the right thalamus, extending into the lateral ventricle and crossing the midline. It contained areas of calcification and showed slight enhancement after contrast injection. On magnetic resonance imaging (MRI) scan, the tumour was hypointense to the brain in T1-weighted images and was heterogeneously hyperintense to the brain in T2-weighted images.

Central neurocytoma: proliferative potential and biological behavior

The authors analyzed 13 central neurocytomas diagnosed at Seoul National University Hospital between January 1982 and December 1993 to clarify the proliferative potential and biological behavior of these tumors. The tumor was confined to the lateral and third ventricles in 12 cases and in one case extended from the posterior thalamus to the body and trigone area of the lateral ventricle. In all 13 cases, typical clinical and radiological findings were observed, and histological diagnosis was performed via craniotomy. The diagnosis was made using light microscopic examination, immunohistochemical staining for neuronal markers, and electron microscopic findings of neuronal differentiation. One patient died due to tumor progression with recurrence 26 months after subtotal removal plus radiation therapy. Another patient had a recurrence 18 months after total tumor removal. The remaining 11 patients are free of recurrent tumor after a follow-up period that ranged from 14 to 109 months (median 50 months). To predict the proliferative potential, immunoreactivity to proliferating cell nuclear antigen (PCNA), silver colloid staining for nucleolar organizing regions (AgNORs), and DNA flow cytometry were performed in 10 of the 13 cases. The proportion of PCNA-positive cells was less than 1% in all cases and the AgNORs score ranged from 1.11 to 2.0 (mean 1.67). The DNA flow cytometry revealed diploidy in all cases and the calculated proliferation index ranged from 5.1% to 9.6% (mean 7.8%). The one case of tumor recurrence, in which the authors performed the study of proliferative potential, and another case that demonstrated mild nuclear pleomorphism also showed low percentages of PCNA-positive cells, low AgNORs scores, and diploidy in DNA flow cytometry. It is suggested that most central neurocytomas follow a benign clinical course with low proliferative potential assessed by PCNA, AgNORs, and DNA flow cytometry; however, recurrence is possible within a relatively short time period.

Central neurocytoma: clinical, immunohistologic, and biologic findings of a human neuroglial progenitor tumor

BACKGROUND

Central neurocytomas are rare brain tumors recognized by their typical radiologic and histologic features. In general, a good prognosis is achieved by total removal. The histogenesis is still under debate, but a neuronal origin is widely assumed.

METHODS

This study presents the clinical and immunohistologic findings of five patients and the results of cell culture experiments of two patients with central neurocytoma treated surgically between 1983 and 1993.

RESULTS

The patient age at diagnosis ranged from 21 to 30 years (mean, 25 years). The male-to-female ration was 1:4. Raised intracranial pressure due to hydrocephalus was the main cause of the clinical manifestations. Total resection was achieved in two cases. Four patients received radiotherapy. One patient suffered a recurrence 1 year after surgery, requiring a second resection and radiotherapy. Follow-up studies took place between 1 and 10.5 years (mean, 7.1 years). To date, all patients are free of their tumors. Two patients suffered from permanent memory disturbances after surgery. Immunohistochemistry confirmed the neuronal nature of the tumors. Cell-culture studies, which have been carried out for the first time, demonstrated concomitant expression of neuronal (synaptophysin) and glial (GFAP) markers.

CONCLUSION

Total removal is the therapy of choice. In tumor recurrence or limited surgery (e.g. due to severe affliction of the fornical structures), radiotherapy has shown to be efficacious. The cell-culture experiments give new insight on the histogenesis of central neurocytoma, indicating that the tumor arises from an undifferentiated precursor cell with the capacity of bipotential neuroglial differentiation.

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 neurocytoma: clinico-pathological study of 5 cases and review of the literature

Five cases of central neurocytoma, confirmed by immunohistochemical and electron microscopy studies, are reported and 127 cases from the literature are reviewed. Central neurocytomas are more frequent than previously thought, and will be diagnosed with increasing frequency in the future, if intraventricular tumors with histological aspect of oligodendroglioma or ependymoma will be routinely studied by immunohistochemistry and electron microscopy. The occurrence of an intraventricular tumor with a typical MR aspect in a young patient should suggest preoperatively the diagnosis of neurocytoma. The positivity for synaptophysin and neuron specific enolase, the negativity for neurofilament protein and glial fibrillary acid protein, and the finding of elements of neuronal differentiation on electron microscopy, are the main pathological features of these tumors. Complete removal of the tumor mass without radiotherapy is the treatment of choice. The prognosis is usually favorable without recurrence.

Giant central neurocytoma with tetraventricular and extra-axial extension. Case report

The central neurocytoma is a recently recognized benign intraventricular tumour of young adults. The authors report a unique case of a panventricular neurocytoma with extension to the interpeduncular and prepontique cisterns which developed in a 35-year-old woman with a 7-year history of headaches and amenorrhea. They review the different pathological and topographical patterns of previously published neurocytomas and discuss the histogenesis of this rare tumour.

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

Characterised by distinctive clinicopathological features, the central neurocytoma (CN) is an uncommon and possibly under-recognised primary cerebral neuronal neoplasm. We present clinical and pathological details of seven patients with CN. Histological examination revealed a greater diversity of morphological appearances than is typically described in CN. No anaplastic features were identified. Cellular areas resembling both oligodendroglioma and ependymoma were present in all cases, but each tumour also contained stroma rich areas with hyalinised or aneurysmal vessels. Synaptophysin was expressed by all tumours and probably represents the immunohistochemical marker of choice for identifying CN. Distinguishing ultrastructural features included rounded cell bodies separated by numerous cell processes containing microtubules, pleomorphic neurosecretory granules and occasional synapses. Ki-67 immunostaining revealed a low cell proliferation index in each case. The distinction of CN from other pathological mimics can be reliably made using this multiparametric approach to diagnosis. The generally benign behaviour of CN is confirmed, though there was one patient death in the follow-up period of 10-122 months. Aggressive behaviour in this case was not associated with anaplastic histological features.