Bithalamic involvement predicts poor outcome among children with thalamic glial tumors

Surgical Treatment of Paediatric Thalamic Gliomas-Single-Centre Experience

The surgical treatment of paediatric thalamic gliomas has been burdened with high morbidity, and these lesions were often considered inoperable. With new approaches and intraoperative technologies, we can remove tumours once deemed inoperable. In our single centre, we have operated on 11 paediatric patients over the course of 8 years. We have performed eight GTR resections and three intended subtotal resections. The postoperative neurological deficit ranged from mild to very severe for motor weakness and none to severe for aphasia after surgery, with all of the patients improving at 3-month follow-up. Radicality in the surgical approach to thalamic gliomas in children has shown significant benefits when compared to more conservative approaches. For children with LGGs, extensive surgical resection is associated with improved prognosis and longer progression-free survival. However, it does not yield the same proportional benefit for HGGs due to its aggressive nature and worse outlook.

Novel therapeutic approaches for pediatric diencephalic tumors: improving functional outcomes

Pediatric diencephalic tumors represent a histopathologically and molecularly diverse group of neoplasms arising in the central part of the brain and involving eloquent structures, including the hypothalamic-pituitary axis (HPA), optic pathway, thalamus, and pineal gland. Presenting symptoms can include significant neurological, endocrine, or visual manifestations which may be exacerbated by injudicious intervention. Upfront multidisciplinary assessment and coordinated management is crucial from the outset to ensure best short- and long-term functional outcomes. In this review we discuss the clinical and pathological features of the neoplastic entities arising in this location, and their management. We emphasize a clear move towards 'function preserving' diagnostic and therapeutic approaches with novel toxicity-sparing strategies, including targeted therapies.

Primary adult unilateral thalamic pilocytic astrocytoma with von Recklinghausen's disease mimicking lymphoma: A case report

Thalamic astrocytomas are rare central nervous system tumors that account for 1%-1.5% of all brain tumors. Their Clinical features depend on anatomical involvement. For these tumors, gross total resection is so difficult due to their deep location and also the infiltration of the optic pathway or brain stem. Unilateral adult thalamic locations are rarely described in the literature. Their radiological features often suggest lymphoma. The authors report here a new case of a primary unilateral thalamic pilocytic astrocytoma mimicking lymphoma diagnosed after a stereotactic core biopsy in a 62-year-old male patient with von Recklinghausen's disease and which is responsible for Dejerine–Roussy syndrome. The authors will proceed with a comprehensive review of literature regarding this rare entity.

Evolution of surgical attitudes to paediatric thalamic tumours: the alder hey experience

PURPOSE

Attitudes to surgery for paediatric thalamic tumours have evolved due to improved preoperative imaging modalities and the advent of intraoperative MRI (iMRI) as well as enhanced understanding of tumour biology. We review the developments in our local practice over the last three decades with particular attention to the impact of iMRI.

METHODS

We identified all paediatric patients from a prospectively maintained neuro-oncology database who received surgery for a thalamic tumour (n = 30). All children were treated in a single UK tertiary paediatric neurosurgery centre between January 1991 and June 2020. Twenty patients underwent surgical resection, the remainder (10) undergoing biopsy only. Pre-operative surgical intent (biopsy versus debulking, near-total resection, or complete resection) as well as the use of iMRI were prospectively recorded. Complications recorded in clinical documentation between postoperative days 0 and 30 were retrospectively graded using a modified version of the Clavien Dindo scale. The extent of resection with respect to the pre-determined surgical aim was also recorded. Data on patient survival and disease progression status were obtained retrospectively.

RESULTS

In our series, there were 42 procedures (25 craniotomies, 17 biopsies) performed on 30 patients (17 male, with a median age of 8 at surgery). Of the 25 surgical resections performed, complete resection was achieved in 9 (36%), near-total resection in 10 (40%), and limited debulking in 6 (24%). The predetermined surgical aim was achieved or exceeded in 91.3% of cases. The proportion of craniotomies for which substantial resection was achieved, increased from 37.5 to 94.2% with use of iMRI (p = 0.014). Surgical morbidity was not associated with greater extent of surgical resection. High-grade histology is identified as the only independent significant factor influencing overall survival as calculated by Cox proportional hazards model (p = 0.006).

CONCLUSION

We note a significant change in the rate and extent of attempted resection of paediatric thalamic tumours that has developed over the last 3 decades. Use of iMRI is associated with a significant increase in substantial tumour resection surgeries. This is not associated with any significant level of surgical morbidity. Improvements in pre- and intra-operative imaging alongside better understanding of tumour biology facilitate patient selection and a surgically more aggressive approach in selected cases whilst maintaining safety and avoiding operative morbidity.

Infiltrative gliomas of the thalamus in children: the role of surgery in the era of H3 K27M mutant midline gliomas

Background

The role of surgery in the management of pediatric non-pilocytic infiltrative thalamic gliomas needs to be revisited specifically with regard to molecularly defined subtypes.

Methods

A retrospective review of a consecutive series of children operated on a thalamic tumor between 1992 and May 2018 was performed. Neuroimaging data were reviewed for localization and extent of resection; pathology was re-reviewed according to the current WHO classification, including assessment of histone H3 K27 mutational status.

Results

Forty-nine patients with a thalamic tumor aged < 18 years at diagnosis were identified. Twenty-five patients (51%) had a non-pilocytic infiltrative glioma, of which the H3 K27M status was available in 22. Fourteen patients were diagnosed as diffuse midline glioma (DMG) H3 K27M mutant. There was no statistically significant difference in survival between patients harboring the H3 K27M mutation and wildtype. Resection (“any resection > 50%” vs “biopsy”) and histological tumor grade (“°II” vs “°III+°IV”) were statistically significant predictors of survival (univariate: p = 0.044 and p = 0.013, respectively). These results remained significant on multivariate analysis (HR 0.371/p = 0.048, HR 9.433/p = 0.035).

Conclusion

We advocate to still consider an attempt at maximal safe resection in the multidisciplinary treatment of unilateral thalamic non-pilocytic gliomas irrespective of their H3 K27-mutational status.

Lateral or Medial Surgical Approaches for Thalamic Gliomas Resection?

OBJECTIVE

This study aimed to investigate the selection, safety, and prognosis of medial (transcorpus callosal) and lateral (translateral brain gyrus) approaches for adult thalamic glioma resection.

METHODS

The medical records of adult patients with thalamic glioma between March 2006 and March 2016 in Huashan Hospital were reviewed. The probabilistic map of the gliomas was shown in Montreal Neurological Institute (MNI) space, and a paralleling midline was delineated to decide the approach. The extent of resection, complications, adjuvant treatment, and survival data were analyzed. A literature review was also conducted.

RESULTS

Fifty-three patients with thalamic glioma were enrolled. Eighteen patients received tumor resection by a medial approach and 35 by a lateral approach. The probabilistic map based on 20 patients showed that 9 gliomas with ≥45% located in the medial side were treated medially and the other 11 gliomas were treated laterally. Both approaches achieved adequate extent of resection with similar morbidity. Kaplan-Meier analysis showed no significant difference of overall survival by a transcorpus callosal or translateral brain gyrus approach. Total resection (TR) or subtotal resection (STR) (P = 0.0003), radiochemotherapy (P < 0.0001), and low-grade glioma (P = 0.031) were correlated with better OS. Multivariate Cox regression analysis showed that TR/STR (P = 0.007; 95% confidence interval, 1.345-6.287) and radiochemotherapy (P < 0.0001; 95% confidence interval, 4.740-71.569) were independent prognostic factors for adult thalamic gliomas.

CONCLUSIONS

Both medial and lateral approaches are feasible and adequate for resection of thalamic gliomas. The paramidline paralleling midline crossing the genu of the internal capsule could help make the choice. TR/STR, radiochemotherapy, and low-grade glioma could benefit the prognosis.

Challenges in the management of childhood low-grade glioma in a developing country

BACKGROUND

Treatment modality impacts outcome of childhood low-grade glioma (LGG). Optimizing management in developing countries can be challenging. This study evaluates the clinical characteristics, treatment, and factors influencing outcome of childhood LGG in Saudi Arabia.

PATIENTS AND METHODS

This study retrospectively evaluated 59 children consecutively diagnosed with LGG between January 2001 and June 2016.

RESULTS

Median age at diagnosis was 6.0 years. Pilocytic astrocytoma represented 64.9% of cases. The anatomic site was cerebellar in 23.7%, cerebral in 18.6%, hypothalamic-optic pathway in 33.9%, and midline in 23.7%. The 5-year overall survival (OS) and progression-free survival (PFS) were 90.6 ± 4.7 and 54.3 ± 8.4%, respectively. Initial treatment was observation in 28.8%, surgery alone in 35.6%, chemotherapy in 13.6%, radiotherapy in 5.1%, and combined in 16.9% of cases. The corresponding 5-year PFS was 56.3 ± 15.6, 53.3 ± 14.0, 22.9 ± 19.7, 33.3 ± 27.2, and 88.9 ± 10.5%, respectively (p = 0.006). Among the 61% who had surgical intervention (either alone or in combination with other therapies), 22% achieved complete resection with 5-year radiation/progression-free survival (RPFS) of 87.5 ± 11.7% compared to 27.6 ± 10.8% for subtotal resection/biopsy and 62.2 ± 17.0% for no surgery (p = 0.013). Adjuvant therapy for residual tumor improved survival with 5-year PFS of 66.7 ± 19.2% for chemotherapy and 100% for radiotherapy compared to 12.5 ± 11.4% for observation (p = 0.033).

CONCLUSIONS

We identified variability in the outcomes of LGG. Fewer surgeries with lower rates of total resection were noted, compared to reports from international cooperative groups. The extent of resection was predictive of RPFS. Adjuvant therapy improved the outcome of patients with residual disease, resulting in PFS rates comparable to international data.

Pediatric Thalamic Gliomas: An Updated Review

CONTEXT

- Neoplasms originating in the thalamus are rare overall (1% of all brain tumors); however, they comprise approximately 5% of pediatric intracranial tumors and approach 15% of all malignant pediatric intracranial tumors in some series.

OBJECTIVE

- To update readers about the current understanding of the diverse histology, biology, and behavior of pediatric thalamic tumors. Histologic verification is now thought to be critical for planning treatment, and, as a result, biopsy and total/subtotal resections are much more common today than in the past.

DATA SOURCES

- A PubMed search using the keywords "pediatric + thalamic + glioma" yielded 45 publications with a total of 445 cases of thalamic gliomas in patients less than 18 years of age. We found only 9 substantial institutional series tabulating all encountered thalamic histologic types in children. This survey confirmed a high proportion of astrocytomas, 81% (214 of 265), of which approximately two-thirds were diffuse astrocytomas (146 of 214) and one-third were pilocytic astrocytomas (68 of 214). Of the diffuse astrocytomas, 34% (49 of 146) were low grade (World Health Organization grade II) and 55% (81 of 146) were high grade (World Health Organization grade III or IV), making the latter subgroup the largest single category of all pediatric thalamic tumors. Oligodendrogliomas and ependymomas (mostly anaplastic in both cases) comprised 10% and 3% of all pediatric thalamic tumors, respectively.

CONCLUSIONS

- Tissue diagnosis is now thought crucial for prognostication and treatment, particularly as more potentially therapeutic molecular targets are discovered. Secure diagnosis allows identification of tumors for which resection is more feasible and beneficial.

Identification and targeting of an FGFR fusion in a pediatric thalamic "central oligodendroglioma"

Approximately 1–5% of pediatric intracranial tumors originate in the thalamus. While great strides have been made to identify consistent molecular markers in adult oligodendrogliomas, such as the 1p/19q co-deletion, it is widely recognized that pediatric oligodendrogliomas have a vastly different molecular make-up. While pediatric thalamic or “central oligodendrogliomas” are histologically similar to peripheral pediatric oligodendrogliomas, they are behaviorally distinct and likely represent a cohesive, but entirely different entity. We describe a case of a 10-year-old girl who was diagnosed with an anaplastic glioma with features consistent with the aggressive entity often diagnosed as central or thalamic oligodendroglioma. We performed whole-exome (paired tumor and germline DNA) and transcriptome (tumor RNA) sequencing, which demonstrated an FGFR3-PHGDH fusion. We describe this fusion and our rationale for pursuing personalized, targeted therapy for the patient’s tumor that may potentially play a role in the treatment of similar cases.

Bithalamic gliomas may be molecularly distinct from their unilateral high-grade counterparts

Bithalamic gliomas are rare cancers diagnosed based on poorly defined radiologic criteria. Infiltrative astrocytomas account for most cases. While some previous studies reported dismal outcomes for patients with bithalamic gliomas irrespective of therapy and histologic grade, others described better prognoses even without anticancer therapy. Little is known about their molecular characteristics. We reviewed clinical, radiologic, and histologic features of patients with bithalamic gliomas treated at our institution over 15 years. Targeted sequencing of mutational hotspots in H3F3A, HIST1H3B, IDH1/2, and BRAF, and genome-wide analysis of DNA methylation and copy number abnormalities was performed in available tumors. Eleven patients with bithalamic gliomas were identified. Their median age at diagnosis was 4.8 years (range: 1-15.7). Additional involvement of the brainstem, basal ganglia, and cerebral lobes occurred in 11, 9, and 3 cases, respectively. All patients presented with hydrocephalus. Two-thirds of the patients had a histologic diagnosis of anaplastic astrocytoma. Despite aggressive therapy, our youngest patient, the only one diagnosed before 1 year of age, is the sole long-term survivor. DNA methylation could be performed in seven tumors, all of which clustered with the RTK I 'PDGFRA' subgroup by unsupervised hierarchical analysis of methylation array against a previously published cohort of 59 pediatric high-grade gliomas. Sequencing of hotspots mutations could be done in 10 tumors, none of which harbored H3F3A p.K27 and/or the respective DNA methylation signature, and any other hotspot mutations. Amplification of MDM4 (n = 2), PDGFRA (n = 2), and ID2 combined with MYCN (n = 1) were observed in 7 tumors available for analysis. In comparison with the previously published experience with unilateral high-grade thalamic astrocytomas where H3F3A p.K27 was present in two-thirds of cases, the absence of this molecular subgroup in bithalamic gliomas was striking. This finding suggests that unilateral and bithalamic high-grade gliomas may represent two distinct molecular entities.

Management of primary thalamic low-grade glioma in pediatric patients: results of the multicenter treatment studies HIT-LGG 1996 and SIOP-LGG 2004

Background

Thalamic low-grade glioma (LGG) poses a special therapeutic challenge, as complete resection is often not possible. To determine the survival outcomes of mono- and bithalamic LGG, we analyzed a large cohort of pediatric patients.

Methods

From 1996 until 2012, 2618 patients were registered in the HIT-LGG 1996 and the SIOP-LGG 2004 studies. A total of 102 of these 2618 patients (3.9%) were diagnosed with a thalamic LGG with a median age at diagnosis of 8.0 years (range, 0.4-17.5 years); 87 patients (85%) had monothalamic and 15 patients (15%) had bithalamic LGG.

Results

Ninety patients received at least one surgical procedure. Thirty-one patients received radiotherapy and 24 patients received chemotherapy as a first-line, nonsurgical treatment indicated by radiological tumor progression or severe/progressive clinical symptoms. Patients with monothalamic tumors showed a 10-year overall survival (OS) rate of 91%, whereas patients with bithalamic tumors only reached 65% (P = .001). Bithalamic tumors more frequently showed diffuse histology than monothalamic tumors. Patients with diffuse astrocytoma had a lower 10-year OS (68%) than those with pilocytic astrocytoma (93%). The 10-year progression-free survival rate after the start of first nonsurgical treatment was 53% in the radiotherapy group and 34% in the chemotherapy group.

Conclusions

Thalamic glioma was manageable using a strategy that included surgery, observation, chemotherapy, and/or radiotherapy. Radiotherapy could be successfully deferred or obviated in a number of patients. Survival was high in among patients with monothalamic tumors. The worse prognosis associated with bithalamic tumors correlates with the higher rate of diffuse histology in this subgroup, precluding total or near-total resection.

Pediatric thalamic glioma with H3F3A K27M mutation, which was detected before and after malignant transformation: a case report

PURPOSE

Histone H3.3 (H3F3A) mutation in the codon for lysine 27 (K27M) has been found as driver mutations in pediatric glioblastoma and has been suggested to play critical roles in the pathogenesis of thalamic gliomas and diffuse intrinsic pontine gliomas. We report a case of thalamic glioma with H3F3A K27M mutation, which was detected in both the primary tumor diagnosed as diffuse astrocytoma obtained during the first surgery and also in the tumor diagnosed as anaplastic astrocytoma obtained at the second surgery.

CASE PRESENTATION

A 14-year-old girl presented with mild headache. Magnetic resonance imaging (MRI) showed a small intraaxial lesion in the left thalamus, which increased in size. Stereotactic tumor biopsy was performed 2 years after the initial diagnosis, and a pathological diagnosis of diffuse astrocytoma (WHO grade 2) was made. The tumor grew further and showed contrast enhancement on MRI despite 16 months of chemotherapy. Surgical removal via the transcallosal approach was then performed, and postoperative pathological diagnosis was anaplastic astrocytoma (WHO grade 3), indicating malignant transformation of the tumor. Molecular diagnosis of tumor tissue obtained at first and second surgeries revealed H3F3A K27M mutation in both primary and secondary specimens.

CONCLUSION

This report demonstrates minute neuroradiological and pathological features of malignant transformation from thalamic low grade glioma with H3F3A K27M mutation. It is noteworthy that this mutation was found in this case when the tumor was still a low-grade glioma. Tissue sampling for genetic analysis is useful in patients with thalamic gliomas to predict the clinical course and efficacy of treatments.

Cerebral hemispheric low-grade glial tumors in children: preoperative anatomic assessment with MRI and DTI

PURPOSE

The aims of this study are to analyze how the nature and the behavior of low-grade glial tumors (LGGT) in children may correlate with the anatomy of the cerebral hemispheres and to evaluate the consequent impact of diffusion tensor imaging (DTI) techniques in the presurgical assessment.

METHODS

This is a combined review of a series of 155 cases of LGGT and of the recent literature on the subject.

RESULTS

The cases retrieved from our data bank were divided in central hemispheric tumors (basal ganglia and thalami) (36 cases), glioneuronal cortical-based tumors (49 cases), and glial tumors of the cerebral mantle (70 cases). A close correlation was found in the thalamus between the primary location of the tumor (juxta-ventricular, inferior, lateral, bilateral) and its extension (ventricular lumen, midbrain and mesial temporal, globus pallidus, respectively) which may relate to the connectivity. Among the glioneuronal tumors, most gangliogliomas were located in the temporal lobe and especially in the mesial temporal structures. In addition, the morphologic feature of the ganglioglioma was different there from the neocortical areas. As a complementary approach, DTI data may assist in evaluating the structure and the extension of the LGGT, in addition to planning the surgical strategy.

CONCLUSIONS

In the cerebral hemispheres like in the rest of the central nervous system, there is some degree of correlation between the anatomy and the nature, appearance, and behavior of the LGGT in children.

Clinical, radiological, and pathological features of 33 adult unilateral thalamic gliomas

Background

Unilateral adult thalamic gliomas are rarely reported. In this study, the authors aimed to analyze the clinical, radiological, and pathological features of adult primary unilateral thalamus gliomas (UTGs).

Methods

Clinical data of 33 UTGs in adults who underwent surgical treatment between 2005 and 2014 at the Beijing Tiantan Hospital were collected and retrospectively studied. Follow-up evaluation was performed.

Results

This study included 21 males and 12 females with a mean age of 43.1 years. The most common symptoms were headache (75.8 %, 25/33 patients) and motor deficits (42.4 %, 14/33 patients). Radiological results showed that enhancement was common (90.9 %, 30/33 patients) and included cystic appearances in 9 cases (27.3 %). All patients underwent maximal safe tumor resection. Gross total resection (GTR) was achieved in 19 cases, subtotal resection (≥80 %) in 9 cases, and partial resection (<80 %) in 5 cases. Molecular pathology results were available in 15 cases. After surgery, 25 patients received postoperative adjuvant therapy based on the remaining pathology. The median follow-up period of all 33 patients with UTGs was 17 months (1 week~49 months). Twenty-four patients experienced tumor recurrence. The 1-year and 2-year progression-free survival (PFS) rates were 49.0 and 10.2 %, respectively. The 1-year and 2-year overall survival (OS) rates were 68.1 and 25.9 %, respectively. Survival analyses revealed that several predictive factors were correlated with better prognosis, among which, GTR and tumor with cystic appearances were significantly associated with a longer survival.

Conclusions

Adult UTGs displayed a wide spectrum of clinical features. GTR can be achieved in adult UTGs with acceptable complications and conferred a better prognosis. Tumor with cystic appearance may indicate better prognosis. More patients and longer follow-up periods are needed to further elucidate the biological features of adult UTGs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12957-016-0820-x) contains supplementary material, which is available to authorized users.

Pediatric thalamic tumors in the MRI era: a Canadian perspective

BACKGROUND

Thalamic gliomas are rare. The natural history is unpredictable, and the optimal management of these tumors in children is poorly defined. The aim was to identify outcomes, prognostic factors, and response to various modalities of treatment in a relatively large population of pediatric thalamic tumors from many centers within a fairly homogeneous health care system.

METHODS

We performed a Canadian multicenter retrospective review of pediatric thalamic tumors presenting during the MRI era (1989-2012). Radiology and pathology were reviewed by central independent reviewers. Paraffin shavings for RNA extraction were taken and tested for fusion events involving KIAA1549:BRAF. Tumors were classified as unilateral or bithalamic based on their origin on imaging. Univariate and multivariate analyses on factors influencing survival were performed.

RESULTS

Seventy-two thalamic tumors were identified from 11 institutions. Females represented 53% of the study population, and the mean age at presentation was 8.9 years. Sixty-two tumors were unilateral and 10 bithalamic. Unilateral tumors had a greater propensity to grow inferiorly towards the brainstem. These tumors were predominantly low grade in comparison to bithalamic tumors which were high-grade astrocytomas. The 5-year overall survival was 61 ± 13% for unithalamic tumors compared to 37 ± 32% for bithalamic tumors (p = 0.097). Multivariate analysis indicated tumor grade as the only significant prognostic factor for unithalamic tumors. Six unilateral tumors, all low grade, were BRAF fusion positive.

CONCLUSION

Unilateral and bilateral thalamic tumors behave differently. Surgical resection is an appropriate treatment option in unilateral tumors, most of which are low grade, but outcome is not related to extent of resection (EOR). Bilateral thalamic tumors have a poorer prognosis, but the occasional patient does remarkably well. The efficacy of chemotherapy and radiotherapy has not been clearly demonstrated. Novel therapeutic approaches are required to improve the prognosis for malignant unilateral thalamic tumors and bilateral thalamic tumors.

Practical neuroimaging of central nervous system tumors for surgical pathologists

Imaging has established itself as an irreplaceable component of neuro-oncology, and provided much insight in all aspects of central nervous system (CNS) tumors. Today, similar to some other medical specialties, such as bone and joint disorders, it is an integral part of the diagnosis of CNS tumors. This brief review highlights the critical elements of neuroimaging, especially of MRI, in the study and diagnosis of brain tumors, and considers some of the common entities for the diagnosis, of which a good understanding of imaging characteristics is extremely helpful.

Thalamic tumors in children

INTRODUCTION

Thalamic tumors are rare tumors which are usually diagnosed in the pediatric age group. Although recent developments in neurosurgical practice allow more radical treatments, information about outcome is scarce for these deep-seated challenging tumors.

METHODS

Medical records of 45 pediatric patients who presented with thalamic tumors between 1999 and 2012 were reviewed.

DISCUSSION

Prognostic implication of tumor characteristics and patient variables are discussed. Although challenging, recent innovations in the field of neurosurgery and refinements in technique may prolong survival in some cases.

Treatment of low-grade gliomas in children: an update

Pediatric low-grade gliomas are a heterogeneous group of tumors that require integration of the pathology and radiographic appearance with the biologic heterogeneity associated with these tumors. Balancing surgery, radiation and chemotherapy to optimize disease control while limiting treatment-related morbidity is of critical importance in this susceptible population and is the focus of this review.

Surgical management of thalamic gliomas: case selection, technical considerations, and review of literature

This study aimed to identify (1) the thalamic gliomas suitable for surgical resection and (2) the appropriate surgical approach based on their location and the displacement of the posterior limb of the internal capsule (PLIC). A retrospective study over a 5-year period (from 2006 to 2010) was performed in 41 patients with thalamic gliomas. The mean age of these patients was 20.4 years (range, 2-65 years). Twenty (49 %) tumors were thalamic, 19 (46 %) were thalamopeduncular, and 2 (5 %) were bilateral. The PLIC, based on T2-weighted magnetic resonance axial sections, was displaced anterolaterally in 23 (56 %) cases and laterally in 6 (14 %) cases. It was involved by lesion in eight (20 %) cases and could not be identified in four (10 %) cases. Resection, favored in patients with well-defined, contrast-enhancing lesions, was performed in 34 (83 %) cases, while a biopsy was resorted to in 7 (17 %) cases. A gross total resection or near total resection (>90 %) could be achieved in 26 (63 %) cases. The middle temporal gyrus approach, used when the PLIC was displaced anterolaterally, was the commonly used approach (63.5 %). Common pathologies were pilocytic astrocytoma (58 %) in children and grade III/IV astrocytomas (86 %) in adults. Preoperative motor deficits improved in 64 % of the patients with pilocytic lesions as compared to 0 % in patients with grade III/IV lesions (P value, 0.001). Postoperatively, two patients (5 %) had marginal worsening of motor power, two patients developed visual field defects, and one patient developed a third nerve paresis. Radical resection of thalamic gliomas is a useful treatment modality in a select subset of patients and is the treatment of choice for pilocytic astrocytomas. Tailoring the surgical approach, depending on the relative position of the PLIC, has an important bearing on outcome.

Thalamic high-grade gliomas in children: a distinct clinical subset?

Pediatric high-grade gliomas (HGGs) of the thalamic region account for up to 13% of pediatric HGGs and usually result in only anecdotal long-term survival. Because very little is known about these tumors, we aimed to further characterize them. In our series of 99 pediatric thalamic HGGs, there were no significant differences in survival between patients with tumors affecting the thalamus alone (including bithalamic lesions) and patients with tumors affecting the thalamus plus adjacent structures. Tumor resection (event-free survival/overall survival) and an early treatment response to radiotherapy/chemotherapy (event-free survival) had independent prognostic significance, as shown by Kaplan-Meier and multivariate Cox regression analyses. When we compared clinical characteristics and outcomes of pediatric thalamic HGG with those of pediatric (nonthalamic) supratentorial (n = 177) as well as pediatric pontine HGG (including diffuse intrinsic pontine gliomas; n = 234), we found that thalamic HGG shared more similarities with pontine than with supratentorial HGG, but overall, it appeared to represent a clinically distinct subgroup of pediatric HGG. The varying extent of tumor resection in the different tumor localizations may play some role in the observed clinical differences, as shown by multivariate Cox regression analyses, but the tumor site itself was also identified as an independent prognostic parameter. Thus, an additional location-specific effect on survival and/or tumor biology, despite different neurosurgical accessibility, has to be considered. Therefore, future investigations should try to further characterize the obviously site-specific heterogeneity of pediatric HGG on a molecular genetic basis.

Surgical management of tumors producing the thalamopeduncular syndrome of childhood

OBJECT

Thalamopeduncular tumors arise at the junction of the inferior thalamus and cerebral peduncle and present with a common clinical syndrome of progressive spastic hemiparesis. Pathologically, these lesions are usually juvenile pilocytic astrocytomas and are best treated with resection with the intent to cure. The goals of this study are to define a common clinical syndrome produced by thalamopeduncular tumors and to discuss imaging characteristics as well as surgical adjuncts, intraoperative nuances, and postoperative complications relating to the resection of these neoplasms.

METHODS

The authors present a retrospective review of their experience with 10 children presenting between 3 and 15 years of age with a thalamopeduncular syndrome. Formal preoperative MR imaging was obtained in all patients, and diffusion tensor (DT) imaging was performed in 9 patients. Postoperative MR imaging was obtained to evaluate the extent of tumor resection. A prospective analysis of clinical outcomes was then conducted by the senior author.

RESULTS

Pilocytic astrocytoma was the pathological diagnosis in 9 cases, and the other was fibrillary astrocytoma. Seven of 9 pilocytic astrocytomas were completely resected. Radical surgery was avoided in 1 child after DT imaging revealed that the corticospinal tract (CST) coursed through the center of the tumor, consistent with the infiltrative nature of fibrillary astrocytoma as identified by stereotactic biopsy. In 8 patients, tractography served as an important adjunct for designing a surgical approach that spared the CST. In 6 cases the CSTs were pushed anterolaterally, making a transsylvian approach a poor choice, as was evidenced by the first patient in the series, who underwent operation prior to the advent of tractography, and who awoke with a dense contralateral hemiparesis. Thus, subsequent patients with this deviation pattern underwent a transcortical approach via the middle temporal gyrus. One patient exhibited medial deviation of the tracts and another had lateral deviation, facilitating a transtemporal and a transfrontal approach, respectively.

CONCLUSIONS

The thalamopeduncular syndrome of progressive spastic hemiparesis presenting in children with or without symptoms of headache should alert the examiner to the possibility of a tumoral involvement of CSTs. Preoperative tractography is a useful adjunct to surgical planning in tumors that displace motor pathways. Gross-total resection of pilocytic astrocytomas usually results in cure, and therefore should be entertained when developing a treatment strategy for thalamopeduncular tumors of childhood.

Bilateral thalamic lesions

OBJECTIVE

Bilateral thalamic lesions are rare and relatively obscure neoplasms. We present our experience with nine cases of bilateral thalamic lesions and attempt to analyse them in the background of available literature.

MATERIALS AND METHODS

Retrospective analyses of the case records of 9 cases of bilateral thalamic lesions treated in our department since January 2002, which have a minimum of 1 year follow-up.

RESULTS

The study group included four males and five females with a mean age of 14.6 years (5 years to 29 years). Seven of these patients had radiological evidence of bilateral thalamic lesions at presentation and 2 patients had involvement of the opposite thalamus at a later stage of the disease. All patients except one presented with raised intracranial pressure symptoms. Focal motor deficits (4/9), behavioral and memory disturbances (3/9) were the other major presenting symptoms. Biopsy confirmation was possible in six patients and histopathology was suggestive of low grade fibrillary astrocytoma in all six patients. Seven patients required CSF diversion procedure for associated hydrocephalus. Eight of our nine patients underwent radiotherapy. On last follow-up, 3 patients were clinically stable with images suggestive of arrested disease, four patients had evidence of progressive disease both clinically and radiologically and there were two recorded cases of mortality.

CONCLUSION

Primary bilateral thalamic lesions have characteristic neuroradiological properties and are distinct from unilateral thalamic tumours with bilateral progression. Almost all of these lesions on histology prove to be gliomas but decompressive surgery is seldom feasible. Surgical intervention is limited to biopsy and CSF diversion for hydrocephalus. Bilateral thalamic lesions remain unresponsive to adjuvant therapy and generally carry a poor prognosis.

Temozolomide in the treatment of children with newly diagnosed diffuse intrinsic pontine gliomas: a report from the Children's Oncology Group

An open-label phase II study (ACNS0126) testing the efficacy of chemoradiotherapy with temozolomide (TMZ) followed by adjuvant TMZ was conducted by the Children's Oncology Group. During the period from July 6, 2004 through September 6, 2005, 63 children with newly diagnosed diffuse intrinsic pontine glioma (DIPG) were enrolled in the study. All patients received TMZ at a dosage of 90 mg/m(2)/day for 42 days to a dose of 59.4 Gy. Four weeks following irradiation, TMZ was given at a dosage of 200 mg/m(2)/day for 5 days every 28 days, for a total of 10 cycles. The primary objective of the statistical analysis was to determine whether the current treatment produced a 1-year event-free survival (EFS) rate higher than the historical baseline of 21.9% observed in CCG-9941. The mean 1-year EFS (± standard deviation) was 14% ± 4.5%, compared with 21.9% ± 5% for CCG-9941. The P value of the test of comparison of 1-year EFS, based on a 1-sided, 1-sample test of proportions, was .96. There was no evidence that temozolomide produced a 1-year EFS rate higher than 21.9%. The mean 1-year OS (± standard deviation) was 40% ± 6.5%, compared with 32% ± 6% for CCG-9941. The median time to death was 9.6 months. Chemoradiotherapy with TMZ followed by adjuvant TMZ is not more effective than previously reported regimens for the treatment of children with DIPG.

Complex neurobehavioural syndrome due to bilateral thalamic glioma

We present a 65-year-old female with bilateral thalamic astrocytoma. The unusual long survival of this patient allowed the manifestation of a complex neurobehavioural syndrome due to gradual involvement of several thalamic nuclei. An attempt is made to approach the complexity of symptoms according to the anatomical areas, nuclei and thalamic connections infiltrated.

Brainstem ganglioglioma

Gangliogliomas are usually benign slow-growing neoplasms, seen mainly in the first 3 decades of life and are prevalently located supratentorial, mostly in the temporal and frontal lobe. The authors present a rare case of a brainstem ganglioglioma in an 11-year-old boy who was referred to their hospital complaining of episodes of blurry vision, loss of memory, gait disturbances, and morning headache with vomiting, lasting for over a month. Computed tomography and magnetic resonance imaging scans revealed a mass on the dorsal surface of the brainstem, compressing the brainstem and producing secondary obstructive hydrocephalus. The patient was operated upon, and the histopathology revealed the presence of a ganglioglioma grade II (World Health Organization classification). On follow-up examination after 1 year, a minor gait imbalance was the only finding. A total resection should be always attempted, where possible in brainstem gangliogliomas. Close follow-up is mandatory, and re-resection or radiotherapy should be considered in case of tumor recurrence.

Thalamic tumors in children: a reappraisal

OBJECT

Two to five percent of pediatric brain tumors are located in the thalamus. The optimal management for these tumors remains unclear. The aim of this study was to determine whether clinical and neuroimaging features could guide treatment, and to what extent these features, together with histological diagnosis and treatment modalities, influenced survival.

METHODS

The records of 69 children who presented with a thalamic tumor between 1989 and 2003 were retrospectively reviewed. Three groups of tumors were analyzed separately: 1) unilateral thalamic tumors (54 lesions); 2) thalamopeduncular tumors (six); and 3) bilateral thalamic tumors (nine). In the patients in whom a unilateral thalamic tumor was diagnosed, 33 had an astrocytic tumor. Of the 54 patients, 32 had a low-grade and 22 had a high-grade tumor. The survival rate was significantly better for patients with the following characteristics: symptom duration longer than 2 months (p < 0.001), lesions with low-grade histological features (p = 0.003), and tumor excision greater than 90% at surgery (p = 0.04). The perioperative morbidity and mortality rates were 37 and 4%, respectively. Fifty-four percent of the patients in this group had a long-term and independent survival. The thalamopeduncular tumors were mostly pilocytic astrocytomas, which had a good prognosis following surgery. The bilateral thalamic tumors in this series were mainly low-grade astrocytic lesions, and more than half of the children attained long-term survival (mean follow-up duration 4.5 years).

CONCLUSIONS

The majority of tumors arising in the thalamus are astrocytic, of which less than half are high-grade lesions. Histological evaluations should be performed in all patients in whom resection is being considered for discrete lesions. Long-term survival is possible in patients with these tumors.

Thalamic gliomas in children: an extensive clinical, neuroradiological and pathological study of 14 cases

OBJECT

Thalamic tumors represent only 1 to 5% of brain neoplasms but frequently affect children. However, pediatric series are rare and go back to several years in spite of recent advances in the neuroradiological, pathological, and molecular fields.

METHODS

We report a series of 14 pediatric thalamic gliomas with clinical, neuroradiological, and pathological studies including p53 immunostaining in 11 cases and 1p19q status in three cases.

RESULTS

Our series included five pilocytic astrocytomas, seven oligodendrogliomas, and two glioblastomas. Pilocytic astrocytomas were characterized by strong contrast enhancement, lack of p53 expression, and excellent prognosis. Oligodendrogliomas frequently demonstrated an aspect of unilateral thalamic enlargement lacking or with slight contrast enhancement. Some of them expressed p53 or demonstrated 1p loss. Anaplastic oligodendrogliomas and glioblastomas displayed a poor outcome, with a mean survival of 8 months after surgery.

CONCLUSION

Our series of pediatric thalamic gliomas clearly distinguishes pilocytic astrocytomas from anaplastic oligodendrogliomas regarding neuroimaging, pathology, and prognosis.

Les astrocytomes pilocytiques du diencéphale de l’enfant

BACKGROUND AND PURPOSE

Pilocytic astrocytoma (PA) is a WHO grade I tumor of the central nervous system mostly arising in children and young adults. Management of diencephalic PA is a difficult challenge. Surgical treatment has to cope with both the difficulties of deep location and eloquent area tumors.

MATERIALS AND METHODS

We retrospectively reviewed seven pediatric cases (female: 4, male: 3) of diencephalic PA. Opto-chiasmatic tumors were excluded from the series. Mean age at diagnosis was 108 months (9 years) (range: 4 month-18 years), median age was 111 months. Median follow-up for the series was 125 months. Tumor locations were as followed: right thalamus: 2, both thalami: 1, hypothalamus: 3, and right basal ganglia: 1. At the onset, the first symptom was mostly raised intracranial pressure. The delay in diagnosis ranged from 48 hours up to 6 years.

TREATMENT

a shunting procedure was performed in 3 patients, a direct surgical approach in 5 patients (gross total removal: 2; partial removal: 3) and one patient had only a biopsy. Three children were re-operated. Three patients were treated by radiationtherapy (RT) after surgery. Chemotherapy was delivered for 4 children.

RESULTS

The overall survival rate was 71.4 months (almost 6 years) (range: 3-184 months). Median survival rate was 42 months (3.5 years). Three children died, two by tumor progression and one death related to late side-effects of RT. Four patients have a good quality of life with GOS I (n = 3) or II (n = 1). We observed tumor regression in two patients at 1 and 17 years after the beginning of treatment. Correct diagnosis was only made for two cases at the initial pathological examination.

CONCLUSION

The course of diencephalic PA is still unpredictable. The tumor can be controlled by a partial surgical removal, and a residual tumor can sometimes decrease in size after surgery. Gross total removal of these tumors, although difficult, may be performed. With cranial navigation systems, the risk is low. Pathological diagnosis is sometimes difficult to assess.

Prognosis-related histomorphological and immunohistochemical markers in central nervous system tumors of childhood and adolescence

Brain tumors account for approximately 20% of all childhood cancers, and are the leading cause of cancer morbidity and mortality among children. Although numerous demographic, clinical and therapeutic parameters have been identified over the past few years that have significant prognostic bearing for some pediatric brain tumors, predicting the clinical course and outcome among children with central nervous system tumors is still difficult. A survey of publications on prognosis-related histopathological and immunohistochemical features among pediatric brain tumors revealed 172 series, of which 91 presented statistically significant outcome-associated parameters as defined by a P value of less than 0.05. Most investigations revealing significant prognosis-related markers were performed on medulloblastomas (30 publications), ependymomas (25) and astrocytic tumors (18). In total, 16 cohorts consisted of more than 100 cases (5 on ependymomas, 3 each on medulloblastomas and astrocytic tumors). On the other hand, there were also 13 series with fewer than 20 cases (5 on medulloblastomas). Potentially prognostic histopathological markers vary among different entities and consist of assessment of necroses, mitoses, differentiation, vascular proliferation, and growth pattern, whereas immunohistochemical features include proliferation markers (Ki-67, MIB-1), expression of oncogenes/tumor suppressor genes and their proteins (TP53, c-erbB2), growth factor and hormonal receptors (VEGF, EGFR, HER2, HER4, ErbB-2), cell cycle genes (p27, p14ARF) and cell adhesion molecules, as well as factors potentially related to therapeutic resistance (DNA topoisomerase IIalpha, metallothionein, P-glycoprotein, tenascin). This review discusses the prognostic potential of histopathological and immunohistochemical markers that can be investigated by the practicing neuropathologist as part of the routine diagnostic workload, and scrutinizes their benefit for predicting therapy response and patient outcome among children with brain tumors.

Pediatric surgical neuro-oncology: current best care practices and strategies

Significant advances have been made in the diagnosis and treatment of childhood brain tumors. Gross total surgical resection combined with appropriate adjuvant therapies can achieve a high rate of disease control for low grade gliomas, ependymomas and medulloblastomas. High grade gliomas, tumors involving the optic apparatus or diencepahalic structures, diffuse brainstem lesions, and recurrent or metastatic disease still pose considerable therapeutic challenges. We review the current treatment strategies of the three most common types of pediatric brain tumors: gliomas, medulloblastomas and ependymomas, and discuss current and future diagnostic and therapeutic modalities.

Subacute diencephalic angioencephalopathy: biopsy diagnosis and radiological features of a rare entity

Subacute diencephalic angioencephalopathy (SDAE) is a rare and fatal disease of unknown etiology that involves the thalami bilaterally. To date, there have been four cases reported, in which the diagnosis was established only after post mortem examination of the brain. We report two male patients, ages 69 and 41 years, who presented with progressive dementia and somnolence. Radiological evaluation revealed enhancing lesions involving both thalami. The differential diagnosis included a number of neoplastic, inflammatory and vascular processes. In both cases, pathological evaluation of biopsy specimens suggested the diagnosis of SDAE. Despite supportive care, the disease progressed rapidly and both patients died within weeks after initial presentation. The diagnosis was confirmed at autopsy in both cases. SDAE is a rare cause of bithalamic disease that can be mistaken for a neoplasm as well as a number of conditions that necessitate different treatment choices. The histopathological findings can establish the diagnosis when combined with radiological and clinical information. This report emphasizes the utility of stereotactic biopsy in early diagnosis of SDAE.

Pathology of diencephalic astrocytomas

Pediatric gliomas span a spectrum of neoplasms ranging from the well-circumscribed, slowly growing lesions that can be totally removed by surgery to highly infiltrating, nonexcisable, rapidly growing tumors that resist any form of postoperative therapy. As part of this symposium, we discuss selected members of this group in the diencephalon, where lesions of both extremes are common in children. The report illustrates and contrasts the clinical, radiographic and pathological features of the two classic regional astrocytomas, pilocytic and fibrillary, as well as two less common but distinctive lesions, pilomyxoid astrocytoma and bithalamic astrocytoma.

Initial management of children with hypothalamic and thalamic tumors and the modifying role of neurofibromatosis-1

Diencephalic gliomas may be grouped into 2 clinical categories. Optic pathway/hypothalamus gliomas (OPG) arise primarily from a slower-growing juvenile pilocytic astrocytoma, and thalamic gliomas arise primarily from a fibrillary astrocytoma which can become clinically and histologically more aggressive. Children with OPG have an excellent long-term prognosis with a 10-year survival of over 85%. The major therapeutic challenge for these patients is to maximize their quality of life by preserving visual and endocrine function while minimizing treatment-related morbidity. Treatment is often initiated at diagnosis in infants and toddlers who have a major visual impairment or the diencephalic syndrome. The judicious application of chemotherapy may serve to forestall the need for radiotherapy or surgery. Children with neurofibromatosis-1 (NF-1) usually have a more indolent course. Tumors may grow more slowly or occasionally regress spontaneously. However, over 90% of children with OPG without NF-1 will require some form of therapy. Patients with thalamic gliomas present with a shorter history, often with hydrocephalus. Surgical intervention is often required to relieve intracranial pressure and establish the histologic identity of the tumor. Over 75% of these tumors will become locally aggressive. Current multimodality therapy is relatively ineffective. The bithalamic variant behaves similarly to a pontine glioma.