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.

Clinical and epidemiological characteristics of pediatric gliosarcomas.

Gliosarcoma (GS) is a glioblastoma with a sarcomatous component that is presumed to be a metaplastic differentiation of glioma cells. We studied the clinical relevance of this histological glioblastoma subentity within the pediatric population. We obtained patient data from the German HIT-GBM database, which contains clinical data for more than 600 pediatric patients with centrally reviewed high-grade gliomas. By applying defined inclusion criteria (diagnosis of GS proven by central neuropathological review; patient age 0 to 21 years), four patients were identified. In addition, after a review of the English medical scientific literature, 19 additional cases were found. The relative frequency of GS in the German HIT-GBM database was only 1.9%. In the whole series of 23 pediatric GS patients, including previously reported cases, the male-to-female-ratio was 1.2:1. GS was found in all pediatric age groups with a median age of 11 years, but there was an unexpectedly high accumulation in infants (6 of 23 <3 years of age, 26%). GS showed a strong predilection of the cerebral hemispheres (22 out of 23 cases). Increased intracranial pressure was the leading symptom of a short clinical history with a median duration of 0.7 month. Interestingly, six patients (26%) were reported with a history of cranial radiotherapy prior to GS diagnosis. In 60% of the GS patients in our series, gross total resection was achieved. Median overall (OS) and event-free survivals (EFS) of the total cohort were 12.1 and 9.8 months, respectively. In conclusion, GS is a very rare tumor entity in children. Literature review suggests a relatively higher incidence in infants and in patients with a previous history of radiotherapy.

Pediatric giant cell glioblastoma: New insights into a rare tumor entity.

Little is known about giant cell glioblastoma (GCG) in pediatric patients. The present study identified 18 pediatric patients with centrally reviewed GCG from the HIT-GBM database of the Gesellschaft für Paediatrische Onkologie und Haematologie in Germany, Austria, and Switzerland. Clinical and epidemiological data were compared with those of 178 pediatric patients with centrally reviewed glioblastoma multiforme (GBM) from the same database. In this unique series, median age, male preference, and median clinical history did not differ significantly between pediatric GCG and GBM patients. GCG showed a stronger predilection for cerebral hemispheres than did GBM, which may only partly explain the higher percentage of gross total tumor resections in GCG patients. Most surprising, the widely distributed hypothesis that GCG may imply a better prognosis than GBM could not be substantiated for our pediatric series. Future studies with larger patient numbers and molecular pathological analyses are still needed to corroborate the present findings and further elucidate the biology of GCG in children.