Gerrit H. Gielen

H3F3A K27M mutation in pediatric CNS tumors: a marker for diffuse high-grade astrocytomas.

Brain tumors are one of the most common childhood malignancies. Diffuse high-grade gliomas represent approximately 10% of pediatric brain tumors. Exon sequencing has identified a mutation in K27M of the histone H3.3 gene (H3F3A K27M and G34R/V) in about 20% of pediatric glioblastomas, but it remains to be seen whether these mutations can be considered specific for pediatric diffuse high-grade astrocytomas or also occur in other pediatric brain tumors. We performed a pyrosequencing-based analysis for the identification of H3F3A codon 27 and codon 34 mutations in 338 pediatric brain tumors. The K27M mutation occurred in 35 of 129 glioblastomas (27.1%) and in 5 of 28 (17.9%) anaplastic astrocytomas. None of the other tumor entities showed H3F3A K27M mutation. Because H3F3A K27M mutations occur exclusively in pediatric diffuse high-grade astrocytomas, analysis of codon 27 mutational status could be useful in the differential diagnosis of these neoplasms.

High frequency of H3F3A K27M mutations characterizes pediatric and adult high-grade gliomas of the spinal cord

We identified 16 HGG (11 glioblastomas, 3 anaplastic astrocytomas and 2 anaplastic gangliogliomas, 16/30, 53 %) and 1 diffuse astrocytoma harboring H3F3A mutations (Fig. 1a–e). The frequency of mutations among HGG affecting adults and children was similar (52 vs. 54 %). The mean age of adult patients with mutated tumors was lower (34 years) than that observed in patients with wild-type tumors (53 years) (Fig. 1f). All tumors affecting infants were H3F3A wild type. The distributions of mutated and wild-type HGG along the spinal cord appeared similar, but in cervical spine HGG were more frequently mutated (Fig. 1g). Neither H3F3A wild-type HGG nor DA showed immunoreactivity for mutant IDH1 protein (not shown). Histones are nuclear proteins which regulate DNA replication and transcription by modifying the nucleosome structure [9]. H3.3 histone proteins, encoded by H3.3A (H3F3A) and H3.3B, are deposited on chromatin in a replication-independent manner and are enriched at actively transcribed genes and heterochromatic regions [9]. H3F3A mutations occur in a hotspot region (K27 and G34) undergoing posttranslational modifications. Similar to IDH1 mutated gliomas in adults, reduced H3.3K27 trimethylation and deregulated DNA methylation are considered to play a major role in pediatric gliomagenesis [2]. Recently, several groups have highlighted the high frequency of H3F3A mutations in pediatric midline HGG as well as in DIPG [2, 3, 7, 8]. These mutations are not limited to pediatric patients, but can occur, although more rarely, in adults. H3F3A mutations were frequently observed in thalamic HGG affecting young adults [1] and adult DIPG, but rare in supratentorial adult HGG [6]. Notably, the patient’s age did not affect the pattern of methylation in H3F3A mutant tumors [1]. Diffuse high-grade gliomas (HGG) in the spinal cord are rare [5]. It is still undetermined whether they could share genetic alterations with their supratentorial counterparts: in particular, because the spinal cord has to be considered a midline structure, a high incidence of H3F3A mutations could be hypothesized, as reported in diffuse pontine gliomas (DIPG) and in pediatric midline HGG [1–3, 6–8]. In this study, we investigated the H3F3A status of 30 primary spinal HGG affecting pediatric and adult patients. Formalin-fixed paraffin-embedded specimens of 36 primary spinal diffusely infiltrating gliomas, including 30 HGG (18 glioblastomas, WHO IV; 10 anaplastic astrocytomas, WHO III; 2 anaplastic gangliogliomas, WHO III) and 6 diffuse astrocytomas (WHO II) [5] were retrieved from the archives of the Institute of Neuropathology, University of Bonn medical Center and of the DGNN Brain Tumor Reference Center, Bonn, Germany. No brainstem HGG were included. The clinical features are summarized in supplementary Table 1. The H3F3A status was evaluated by immunohistochemistry and/or by pyrosequencing, as described previously [4]. Antibodies against mutant H3.3K27M (Millipore, Temecula, USA), methylated H3.3K27me3 protein (Cell Signaling, Danvers, USA) as well as mutant IDH1 protein (Dianova, Hamburg, Germany) were used.

Genetic Analysis of Diffuse High-Grade Astrocytomas in Infancy Defines a Novel Molecular Entity

Pediatric high‐grade gliomas are considered to be different when compared to adult high‐grade gliomas in their pathogenesis and biological behavior. Recently, common genetic alterations, including mutations in the H3F3A/ATRX/DAXX pathway, have been described in approximately 30% of the pediatric cases. However, only few cases of infant high‐grade gliomas have been analyzed so far. We investigated the molecular features of 35 infants with diffuse high‐grade astrocytomas, including 8 anaplastic astrocytomas [World Health Organization (WHO) grade III] and 27 glioblastomas (WHO grade IV) by immunohistochemistry, multiplex ligation probe‐dependent amplification (MLPA), pyrosequencing of glioma‐associated genes and molecular inversion probe (MIP) assay. MIP and MLPA analyses showed that chromosomal alterations are significantly less frequent in infants compared with high‐grade gliomas in older children and adults. We only identified H3F3A K27M in 2 of 34 cases (5.9%), with both tumors located in the posterior fossa. PDGFRA amplifications were absent, and CDKN2A loss could be observed only in two cases. Conversely, 1q gain (22.7%) and 6q loss (18.2%) were identified in a subgroup of tumors. Loss of SNORD located on chromosome 14q32 was observed in 27.3% of the infant tumors, a focal copy number change not previously described in gliomas. Our findings indicate that infant high‐grade gliomas appear to represent a distinct genetic entity suggesting a different pathogenesis and biological behavior.

Extracranial metastasizing solitary fibrous tumors (SFT) of meninges: histopathological features of a case with long-term follow-up.

Extrapleural solitary fibrous tumors are uncommon mesenchymal neoplasms frequently observed in middle‐aged adults and are classified, according to the WHO classification of soft tissue tumors, as part of the hemangiopericytoma tumor group. However, these two entities remain separated in the WHO classification of tumors of the central nervous system. In fact, meningeal solitary fibrous tumors are believed to be benign lesion and only in a minority of cases local relapses have been described, although detailed survival clinical studies on solitary fibrous tumors of meninges are rare. In contrast to hemangiopericytoma, which frequently shows distant extracranial metastases, such an event is exceptional in patients with meningeal solitary fibrous tumors and has been clinically reported in a handful of cases only and their histopathological features have not been investigated in detail. In this report, we describe the detailed clinico‐pathological features of a meningeal solitary fibrous tumor presenting during a 17‐year follow‐up period, multiple intra‐, extracranial relapses and lung metastases.

Clinical, Radiologic, Pathologic, and Molecular Characteristics of Long-Term Survivors of Diffuse Intrinsic Pontine Glioma (DIPG): A Collaborative Report From the International and European Society for Pediatric Oncology DIPG Registries

Purpose Diffuse intrinsic pontine glioma (DIPG) is a brainstem malignancy with a median survival of < 1 year. The International and European Society for Pediatric Oncology DIPG Registries collaborated to compare clinical, radiologic, and histomolecular characteristics between short-term survivors (STSs) and long-term survivors (LTSs). Materials and Methods Data abstracted from registry databases included patients from North America, Australia, Germany, Austria, Switzerland, the Netherlands, Italy, France, the United Kingdom, and Croatia. Results Among 1,130 pediatric and young adults with radiographically confirmed DIPG, 122 (11%) were excluded. Of the 1,008 remaining patients, 101 (10%) were LTSs (survival ≥ 2 years). Median survival time was 11 months (interquartile range, 7.5 to 16 months), and 1-, 2-, 3-, 4-, and 5-year survival rates were 42.3% (95% CI, 38.1% to 44.1%), 9.6% (95% CI, 7.8% to 11.3%), 4.3% (95% CI, 3.2% to 5.8%), 3.2% (95% CI, 2.4% to 4.6%), and 2.2% (95% CI, 1.4% to 3.4%), respectively. LTSs, compared with STSs, more commonly presented at age < 3 or > 10 years (11% v 3% and 33% v 23%, respectively; P < .001) and with longer symptom duration ( P < .001). STSs, compared with LTSs, more commonly presented with cranial nerve palsy (83% v 73%, respectively; P = .008), ring enhancement (38% v 23%, respectively; P = .007), necrosis (42% v 26%, respectively; P = .009), and extrapontine extension (92% v 86%, respectively; P = .04). LTSs more commonly received systemic therapy at diagnosis (88% v 75% for STSs; P = .005). Biopsies and autopsies were performed in 299 patients (30%) and 77 patients (10%), respectively; 181 tumors (48%) were molecularly characterized. LTSs were more likely to harbor a HIST1H3B mutation (odds ratio, 1.28; 95% CI, 1.1 to 1.5; P = .002). Conclusion We report clinical, radiologic, and molecular factors that correlate with survival in children and young adults with DIPG, which are important for risk stratification in future clinical trials.

KPNA2 predicts long term survival in patients with anaplastic oligoastrocytomas

The family of karyopherins comprises importins and exportins which are both involved in nucleocytoplasmic shuttling. Increased levels of karyopherin a2/importin 1 (KPNA2) and chromosome region maintenance protein 1/exportin 1 (CRM1) have been associated with poorer prognosis in patients with infiltrative astrocytomas. Isocitrate dehydrogenase 1 gene (IDH1) R132H mutation status was also recently identified as a prognostic factor for malignant gliomas. We evaluated KPNA2 and CRM1, as well as the IDH1 mutation status, as possible novel biomarkers for World Health Organization grade III anaplastic oligoastrocytomas (AOA). We analyzed nuclear expression of KPNA2 by immunohistochemistry in 72 primary anaplastic gliomas (29 AOA, 24 anaplastic astrocytomas, 19 anaplastic oligodendrogliomas). The IDH1 mutation status was also determined in patients with anaplastic astrocytomas and AOA, and AOA patients were additionally evaluated for CRM1 nuclear expression. Long term survivors (LTS; >8 years) with AOA showed lower KPNA2 expression levels compared to non-LTS (p=0.005). KPNA2 expression (⩾ 5% versus <5%, 1-<5%, median) was found to correlate inversely with overall survival (OS) and progression-free survival (PFS) in our overall series as well as in the AOA group (anaplastic gliomas: OS p=0.017; PFS p=0.033; AOA: OS p=0.017, PFS p=0.040). Mutant IDH1-R132H was detected in 69% of the AOA cohort; a combination of KPNA2 low expression and mutant IDH1-R132H was only seen in LTS (p=0.050). No differences between the histological subtypes were observed in terms of KPNA2 expression and IDH1-R132H mutation status. To our knowledge this is the first time it has been shown that KPNA2 expression may have potential as a prognostic biomarker for AOA as well.

The immediate and short-term effects of bilateral intrahippocampal depth electrodes on verbal memory

In contrast to previous studies, Ljung et al. provide evidence of permanent cognitive consequences of bilateral intrahippocampal depth electrodes for verbal memory in patients who were not operated or operated in the right temporal lobe. Stimulated by this, we provide historical confirmatory and supplementary evidence of the detrimental effect of bilateral depth electrodes implanted along the longitudinal axis of the hippocampus on verbal learning and especially on delayed verbal memory and recognition performance. This is demonstrated in 31 patients with memory assessments before implantation, after explantation, and 3 months later after left/right temporal lobe surgery. After surgery, significant recovery from postimplantation impairment is found in right temporal patients. Left temporal resection patients stay on the level seen after implantation and do not recover. Surgery, however, has its own effects in addition to the implantation. Intracranial electrodes for electroencephalographic monitoring or electrical stimulation are commonly and increasingly used for diagnosis or treatment in pharmacoresistant epilepsies. Thus, the monitoring of invasive stereotactic approaches is recommended to find safe procedures for the patients. In response to the findings, we restricted indications and used different implantation schemes, different trajectories, and targets to minimize the risk of additional damage.

MTSS1 is epigenetically regulated in glioma cells and inhibits glioma cell motility.

Epigenetic silencing by DNA methylation in brain tumors has been reported for many genes, however, their function on pathogenesis needs to be evaluated. We investigated the MTSS1 gene, identified as hypermethylated by differential methylation hybridization (DMH). Fifty-nine glioma tissue samples and seven glioma cell lines were examined for hypermethylation of the MTSS1 promotor, MTSS1 expression levels and gene dosage. GBM cell lines were treated with demethylating agents and interrogated for functional consequences of MTSS1 expression after transient transfection. Hypermethylation was significantly associated with IDH1/2 mutation. Comparative SNP analysis indicates higher incidence of loss of heterozygosity of MTSS1 in anaplastic astrocytomas and secondary glioblastomas as well as hypermethylation of the remaining allele. Reversal of promoter hypermethylation results in an increased MTSS1 expression. Cell motility was significantly inhibited by MTSS1 overexpression without influencing cell growth or apoptosis. Immunofluorescence analysis of MTSS1 in human astrocytes indicates co-localization with actin filaments. MTSS1 is down-regulated by DNA methylation in glioblastoma cell lines and is part of the G-CIMP phenotype in primary glioma tissues. Our data on normal astrocytes suggest a function of MTSS1 at focal contact structures with an impact on migratory capacity but no influence on apoptosis or cellular proliferation.

High-grade glioma in very young children: a rare and particular patient population

In the past years, pediatric high-grade gliomas (HGG) have been the focus of several research articles and reviews, given the recent discoveries on the genetic and molecular levels pointing out a clinico-biological uniqueness of the pediatric population compared to their adult counterparts with HGG. On the other hand, there are only scarce data about HGG in very young children (below 3 years of age at diagnosis) due to their relatively low incidence. However, the few available data suggest further distinction of this very rare subgroup from older children and adults at several levels including their molecular and biological characteristics, their treatment management, as well as their outcome. This review summarizes and discusses the current available knowledge on the epidemiological, neuropathological, genetic and molecular data of this subpopulation. We discuss these findings and differences compared to older patients suffering from the same histologic disease. In addition, we highlight the particular clinical and neuro-radiological findings in this specific subgroup of patients as well as their current management approaches and treatment outcomes.In the past years, pediatric high-grade gliomas (HGG) have been the focus of several research articles and reviews, given the recent discoveries on the genetic and molecular levels pointing out a clinico-biological uniqueness of the pediatric population compared to their adult counterparts with HGG. On the other hand, there are only scarce data about HGG in very young children (below 3 years of age at diagnosis) due to their relatively low incidence. However, the few available data suggest further distinction of this very rare subgroup from older children and adults at several levels including their molecular and biological characteristics, their treatment management, as well as their outcome. This review summarizes and discusses the current available knowledge on the epidemiological, neuropathological, genetic and molecular data of this subpopulation. We discuss these findings and differences compared to older patients suffering from the same histologic disease. In addition, we highlight the particular clinical and neuro-radiological findings in this specific subgroup of patients as well as their current management approaches and treatment outcomes.

INCIDENTAL NEUROPATHOLOGICAL FINDINGS IN A CHILD WITH CERVICAL MENINGORADICULOCELE

After an uncomplicated pregnancy and birth an otherwise healthy girl showed a skin appendix in the dorsal mid-cervical region with a connection to the cervical spinal cord. The lesion was notable in ultrasound examination at the 19 gestational week. At the age of 2 months the patient underwent plastic surgery of a dysraphic malformation with resection of the skin appendix and removal of tethering structures at the dysplastic cervical cord at level C6. The histological examination revealed fibro-adipose tissue containing numerous nerve fascicles with degenerative features. Along the nerve fascicles, a nodule-like lesion composed of “onions bulbs”like structures with up to 10 concentric lamellae and one or more centrally placed axons was present. The cells surrounding the axons appeared focally densely packed. The lesion was compatible with the diagnosis of Pacinian hyperplasia (“Pacinioma”, pacinian neuroma) associated with meningoradiculocele. Although Pacinian hyperplasia occurs preferentially in the hand, some deep seeded localisations have been described and encountered in samples obtained from surgery for spina bifida malformations. Pacinian hyperplasia has not to be confused with other more common neoplastic lesions affecting the spinal cord region. Correspondence 740 Brain Pathology 22 (2012) 737–740