Pediatric brainstem oligodendroglioma

Management and outcome of pediatric brainstem and cerebellar peduncular low-grade gliomas: a retrospective analysis of 62 cases

PURPOSE

This study was designed to present our experience and recommendations regarding the management of pediatric brainstem and peduncular low-grade gliomas (LGGs).

METHODS

Retrospective analysis was performed for pathologically proven brainstem or cerebellar peduncular LGGs in patients admitted between 2014 and 2019. These lesions were classified into the dorsal exophytic, focal brainstem, cervicomedullary, lower peduncular, and upper peduncular groups, and this classification was the basis for the surgical approach for the lesions.

RESULTS

Sixty-two pediatric patients were included, and their distribution among the aforementioned groups were as follows: 12, 12, 3, 16, and 19 cases in the dorsal exophytic, focal brainstem, cervicomedullary, upper peduncular, and lower peduncular groups, respectively. Stereotactic biopsy was performed for all cases in the focal brainstem group, whereas other groups underwent open excision. Gross total resection (GTR) was achieved in 20 cases (40%), near-total resection (NTR) was achieved in 17 cases (34%), and subtotal resection (STR) was achieved in 13 cases (26%). The extent of GTR and NTR for the upper peduncular, lower peduncular, dorsal exophytic, and cervicomedullary groups were 81.2%, 68.4%,75%, and 66.6%, respectively. Then, 32 cases received chemotherapy. The 3- and 5-year progression-free survival rates were 95% (95% confidence interval (CI) 89.5-100%) and 90.3% (95% CI 79.9-100%), respectively. A significant difference in the 3-year progression-free survival rate was observed between the GTR and NTR groups (p = 0.06; 100% vs. 88.2% (95% CI 72.9-100%)).

CONCLUSION

Surgery plays a definitive curative role in grossly resected cases. Additionally, the role of surgical debulking should be considered, even if GTR is impossible. Meanwhile, chemotherapy showed a beneficial role in patients with focal brainstem lesions and progressive lesions, those with STR, and some patients with NTR.

Predictors of clinical outcome in pediatric oligodendroglioma: meta-analysis of individual patient data and multiple imputation

OBJECTIVE Oligodendroglioma is a rare primary CNS neoplasm in the pediatric population, and only a limited number of studies in the literature have characterized this entity. Existing studies are limited by small sample sizes and discrepant interstudy findings in identified prognostic factors. In the present study, the authors aimed to increase the statistical power in evaluating for potential prognostic factors of pediatric oligodendrogliomas and sought to reconcile the discrepant findings present among existing studies by performing an individual-patient-data (IPD) meta-analysis and using multiple imputation to address data not directly available from existing studies. METHODS A systematic search was performed, and all studies found to be related to pediatric oligodendrogliomas and associated outcomes were screened for inclusion. Each study was searched for specific demographic and clinical characteristics of each patient and the duration of event-free survival (EFS) and overall survival (OS). Given that certain demographic and clinical information of each patient was not available within all studies, a multivariable imputation via chained equations model was used to impute missing data after the mechanism of missing data was determined. The primary end points of interest were hazard ratios for EFS and OS, as calculated by the Cox proportional-hazards model. Both univariate and multivariate analyses were performed. The multivariate model was adjusted for age, sex, tumor grade, mixed pathologies, extent of resection, chemotherapy, radiation therapy, tumor location, and initial presentation. A p value of less than 0.05 was considered statistically significant. RESULTS A systematic search identified 24 studies with both time-to-event and IPD characteristics available, and a total of 237 individual cases were available for analysis. A median of 19.4% of the values among clinical, demographic, and outcome variables in the compiled 237 cases were missing. Multivariate Cox regression analysis revealed subtotal resection (p = 0.007 [EFS] and 0.043 [OS]), initial presentation of headache (p = 0.006 [EFS] and 0.004 [OS]), mixed pathologies (p = 0.005 [EFS] and 0.049 [OS]), and location of the tumor in the parietal lobe (p = 0.044 [EFS] and 0.030 [OS]) to be significant predictors of tumor progression or recurrence and death. CONCLUSIONS The use of IPD meta-analysis provides a valuable means for increasing statistical power in investigations of disease entities with a very low incidence. Missing data are common in research, and multiple imputation is a flexible and valid approach for addressing this issue, when it is used conscientiously. Undergoing subtotal resection, having a parietal tumor, having tumors with mixed pathologies, and suffering headaches at the time of diagnosis portended a poorer prognosis in pediatric patients with oligodendroglioma.

Neurosurgical treatment of oligodendroglial tumors in children and adolescents: a single-institution series of 35 consecutive patients

OBJECT

The object of this study was to delineate long-term results of the surgical treatment of pediatric CNS tumors classified as oligodendroglioma (OD) or oligoastrocytoma (OA) WHO Grade II or III.

METHODS

A cohort of 45 consecutive patients 19 years or younger who had undergone primary resection of CNS tumors originally described as oligodendroglial during the years 1970-2009 at a single institution were reviewed in this retrospective study of surgical morbidity, mortality, and academic achievement and/or work participation. Gross motor function and activities of daily living were scored using the Barthel Index (BI).

RESULTS

Patient records for 35 consecutive children and adolescents who had undergone resection for an OA (17 patients) or OD (18 patients) were included in this study. Of the 35 patients, 12 were in the 1st decade of life at the first surgery, whereas 23 were in the 2nd decade. The male/female ratio was 1.19 (19/16). No patient was lost to follow-up. The tumor was localized to the supratentorial compartment in 33 patients, the posterior fossa in 1 patient, and the cervical medulla in 1 patient. Twenty-four tumors were considered to be WHO Grade II, and 11 were classified as WHO Grade III. Among these latter lesions were 2 tumors initially classified as WHO Grade II and later reclassified as WHO Grade III following repeat surgery. Fifty-four tumor resections were performed. Two patients underwent repeat tumor resection within 5 days of the initial procedure, after MRI confirmed residual tumor. Another 10 patients underwent a second resection because of clinical deterioration and progressive disease at time points ranging from 1 month to 10 years after the initial operation. Six patients underwent a third resection, and 1 patient underwent a fourth excision following tumor dissemination to the spinal canal. Sixteen (46%) of the 35 children received adjuvant therapy: 7, fractionated radiotherapy; 4, chemotherapy; and 5, both fractionated radiotherapy and chemotherapy. One patient with primary supratentorial disease experienced clinically malignant development with widespread intraspinal dissemination 9 years after initial treatment. Only 2 patients needed treatment for persistent hydrocephalus. In this series there was no surgical mortality, which was defined as death within 30 days of resection. However, 12 patients in the study, with follow-up times from 1 month to 33 years, died. Twenty-three patients, with follow-up times from 4 to 31 years, remained alive. Among these survivors, the BI was 100 (normal) in 22 patients and 80 in 1 patient. Nineteen patients had full- or part-time work or were in normal school programs.

CONCLUSIONS

Pediatric oligodendroglial tumors are mainly localized to the supratentorial compartment and more often occur in the 2nd decade of life rather than the 1st. Two-thirds of the patients remained alive after follow-ups from 4 to 31 years. Twelve children succumbed to their disease, 9 of them within 3 years of resection despite combined treatment with radio- and chemotherapy. Three of them remained alive from 9 to 33 years after primary resection. Among the 23 survivors, a stable, very long-term result was attainable in at least 20. Five-, 10-, 20-, and 30-year overall survival in patients with Grade II tumors was 92%, 92%, 92%, and 88%, respectively.

Brainstem oligodendroglioma in a puppy

A 5 mo old male golden retriever presented for evaluation of an acute onset, progressive neurologic disease. Although computed tomography (CT) was unremarkable, MRI identified an ill-defined mass located in the medulla, which was considered likely responsible for the clinical signs. The imaging features closely resembled the classic features of human brainstem gliomas in the pediatric population. Histopathologic examination confirmed the lesion to be an anaplastic oligodendroglioma.

Anaplastic oligodendroglioma arising from the brain stem and featuring 1p/19q co-deletion

With respect to localization, oligodendrogliomas are characterized by a marked preponderance of the cerebral hemispheres. Outside these typical sites, any tumor histopathologically reminiscent of oligodendroglioma a priori is likely to represent one of its morphological mimics, including clear cell ependymoma, neurocytoma, pilocytic astrocytoma or glioneuronal tumors. This is particularly relevant as several of the latter are in principle curable by surgery. Among extrahemispherical sites, bona fide oligodendroglioma - as characterized by loss of heterozygosity (LOH) of chromosome arms 1p and 19q - so far has not been documented to occur in the brain stem. Here, we report the case of a 55-year-old female patient with an anaplastic oligodendroglioma (WHO grade III) of the brain stem and cerebellum diagnosed by stereotactic biopsy and featuring combined LOH of 1p and 19q. A morphological peculiarity was a population of interspersed tumor giant cells, a phenomenon that has been referred to as polymorphous oligodendroglioma. Our findings confirm the notion that - although very infrequently - true oligodendrogliomas do occur in the infratentorial compartment.