A case of high‐grade astrocytoma with BRAF and ATRX mutations following a long‐standing course over two decades

Pediatric high‐grade gliomas are rare and occasionally hard to classify. These tumors often feature a well‐demarcated histology and are expected to have a better outcome than ordinary diffuse high‐grade gliomas in adults. We herein report a case of circumscribed high‐grade glioma that showed a distinct molecular profile and followed an excellent course for 26 years. The patient, a 3‐year‐old boy at onset, presented with a contrast‐enhancing mass in the right temporal lobe and underwent resection. Histologically, the tumor mainly consisted of compact bundles of GFAP‐positive spindle cells. With its malignant features including brisk mitotic activity and pseudopallisading necrosis, a diagnosis of high‐grade astrocytoma was made and adjuvant chemoradiotherapy was administered. After a disease‐free period of two decades, the tumor recurred locally. The resected tumor was histologically identical to the primary tumor and additionally contained pleomorphic cells, but lacked eosinophilic granular bodies and reticulin networks. The primary and recurrent tumors both harbored the BRAF V600E mutation, and the recurrent tumor was immunonegative for ATRX. Combined BRAF and ATRX mutations are rare in gliomas, with only a pediatric case of glioblastoma being reported in the literature. However, our case cannot be regarded as glioblastoma because of its well‐demarcated histology and excellent course. The distinction of either a diffuse or localized nature in gliomas is important, particularly in children, for predicting prognoses and selecting adjuvant therapies that consequently affect life‐long health care. The present case provides novel insights into pediatric high‐grade astrocytomas.     

A comprehensive analysis identifies BRAF hotspot mutations associated with gliomas with peculiar epithelial morphology

Brain tumors harbor various BRAF alterations, the vast majority of which are the BRAF kinase‐activating V600E mutation. BRAF mutations are most frequently detected in certain subtypes of low‐grade glioma, such as pilocytic astrocytoma (PA), pleomorphic xanthoastrocytoma (PXA), ganglioglioma (GG) and dysembryoplastic neuroepithelial tumor (DNT). However, it is unclear whether gliomas harboring BRAF mutations can be invariably regarded as these glioma subtypes or their derivatives. To address this question, we analyzed 274 gliomas in our institutional case series. We performed high‐resolution melting analyses and subsequent direct Sanger sequencing on DNA isolated from snap‐frozen tumor tissues. As expected, BRAF mutations were detected in the aforementioned low‐grade gliomas: in 4/27 PAs, 2/3 PXAs, 4/8 GGs, and 1/6 DNTs. In addition to these gliomas, 1/2 astroblastomas (ABs) and 2/122 glioblastomas (GBs) harbored BRAF mutations. Pathological investigation of the two GBs revealed that one was a GB displaying epithelial features that presumably arose from a precedent GG, whereas the other GB, which harbored a rare G596 A mutation, showed marked epithelial features, including astroblastic rosettes. Our results indicate that in addition to being present in established BRAF‐associated gliomas, BRAF mutations might be associated with epithelial features in high‐grade gliomas, including sheet‐like arrangement of polygonal tumor cells with a plump cytoplasm and astroblastic rosettes, and thus could potentially serve as a genetic marker for these features.     

Combined molecular analysis of BRAF and IDH1 distinguishes pilocytic astrocytoma from diffuse astrocytoma

Separation of pilocytic astrocytoma from diffuse astrocytomas frequently poses problems mostly related to small sample size. Precise classification and grading are essential due to different therapeutic strategies prompted by diagnoses of pilocytic astrocytoma WHO grade I, diffuse astrocytomas WHO grade II or anaplastic astrocytoma WHO grade III. Recently, genomic aberrations with a high specificity for distinct glioma entities have been described. Pilocytic astrocytomas carry a duplication at chromosome band 7q34 containing a BRAF–KIAA1549 gene fusion in the majority of cases. IDH1 mutations are observed very frequently in adult astrocytomas and IDH2 mutations have been reported in some astrocytomas. We examined a series of 120 astrocytomas including 70 pilocytic astrocytomas WHO grade I and 50 diffuse astrocytomas WHO grade II for both, BRAF–KIAA1549 fusion with a newly developed FISH assay and mutations in IDH1 and IDH2 by direct sequencing. Pilocytic astrocytomas contained the BRAF fusion in 49 cases (70%) but neither IDH1 nor IDH2 mutations. Astrocytomas WHO grade II exhibited IDH1 mutations in 38 cases (76%) but neither IDH2 mutations nor BRAF fusions. Thus, combined molecular analysis of BRAF and IDH1 is a sensitive and highly specific approach to separate pilocytic astrocytoma from diffuse astrocytoma.     

Focal cortical dysplasia coexisting with diffuse astrocytoma in childhood: A case report and reappraisal of the glial component in archival FCD cases

We report a rare case of focal cortical dysplasia (FCD) concurring with diffuse astrocytoma and arachnoid cyst, and also re‐evaluate the glial component in archival FCD cases for the differential diagnosis of diffuse gliomas. A 7‐year‐old boy with a 9‐month history of psychomotor seizures disclosed a hyperintense area accompanied by a cystic lesion in the left temporal lobe on MRI. The surgical specimen displayed dyslamination of the cortices and ectopic neurons in the white matter, associated with dysmorphic neurons, indicating FCD type IIA. Additionally, the lesion showed diffuse proliferation and infiltration of glial cells, immunopositive for infiltrating glioma markers (nestin, doublecortin, MAP‐2e) and p53, and MIB‐1 index was 2.0%. These findings indicated coexisting diffuse astrocytoma. Coexistence of diffuse glioma with FCD is unusual, but we often notice increased population of small glial cells in FCD lesions. Re‐evaluation of archival FCD cases with diverse markers revealed that reactive microglia significantly proliferate in the white matter lesions. Therefore, a careful pathological assessment has to be made to define a rare case of diffuse glioma occurring in FCD.     

Calcified astrocytoma of the amygdalo-hippocampal region in children

Three pediatric cases of temporal lobe seizure due to calcified glioma of amygdalo-hippocampal region are described. Computed tomography and magnetic resonance imaging showed dense calcification with no postcontrast enhancement in the amygdalo-hippocampal region. Positron emission tomography showed low oxygen metabolism, low glucose metabolism, hypermetabolism of amino acids, and low regional cerebral blood flow in the tumors. Single photon emission computed tomography showed a high accumulation of²⁰¹Tl chloride and¹²³I-isopropyl iodoamphetamine in one tumor, but otherwise low radioisotope uptake. These studies indicated lowgrade malignancies. The patients were treated by partial tumor removal and radiotherapy. Histological examination of the tumor specimens showed astrocytoma with interstitial calcification. One patient died due to tumor recurrence, while the others are doing well with minimal seizure. We recommended temporal lobectomy in similar cases to achieve complete remission.     

Anaplastic astrocytoma with angiocentric ependymal differentiation

Angiocentric glioma (AG) is an epileptogenic benign cerebral tumor primarily affecting children and young adults, and characterized histopathologically by an angiocentric pattern of growth of monomorphous bipolar cells with features of ependymal differentiation (WHO grade I). We report an unusual cerebral glial tumor in a 66‐year‐old woman with generalized tonic‐clonic seizure; the patient also had a 6‐year history of headache. On MRI, the tumor appeared as a large T2‐hyperintense lesion involving the right insular gyri‐anterior temporal lobe, with post‐contrast enhancement in the insula region. Histopathologically, the tumor involving the insular cortex‐subcortical white matter was composed of GFAP‐positive glial cells showing two different morphologies: one type had monomorphous bipolar cytoplasm and was angiocentric with circumferential alignment to the blood vessels, with dot‐like structures positive for epithelial membrane antigen and a Ki‐67 labeling index of <1%, and the other was apparently astrocytic, being diffusely and more widely distributed in the parenchyma, showing mitoses and a Ki‐67 labeling index of >5%. In the anterior temporal lobe, a diffuse increase in the number of astrocytic cells was evident in part of the cortex and subcortical white matter. On the basis of these findings, we considered whether the present tumor may represent an unusual example of AG with infiltrating astrocytic cells showing primary anaplastic features (AG with anaplastic features), or anaplastic astrocytoma showing primary vascular‐associated ependymal differentiation (anaplastic astrocytoma with angiocentric ependymal differentiation). At present, the latter appears to be the more appropriate interpretation.     

Cerebellar high‐grade astrocytoma with IDH mutations in the elderly: A report of two cases

Cerebellar high‐grade gliomas are rare, and likely to affect younger patients compared with those of cerebral origin. Recent genetic analyses have revealed that isocitrate dehydrogenase (IDH) 1/2 mutations are rare in infratentorial gliomas. In this paper, we report two elderly cases of IDH‐mutated cerebellar high‐grade glioma with unusual histological features and uncommon patient ages. One case was an 83‐year‐old man, whose tumor was predominantly composed of densely packed round‐to‐polygonal epithelioid cells. The other was a 75‐year‐old woman's high‐grade astrocytoma characterized by cord‐like structures and the perivascular papillary arrangements with varying amounts of myxoid matrix. The former harbored IDH1 R132H mutation, whereas the latter had IDH2 R172K mutation. According to our literature review, eight cases of IDH‐mutated infratentorial gliomas including the present cases have been reported, and four had mutations other than IDH1 R132H. Moreover, we herein report the first elderly case of IDH2‐mutation. Although the number is limited, IDH‐mutant infratentorial diffuse gliomas may have clinical, histological and genetic features different from supratentorial cases.     

Spinal cord anaplastic astrocytoma with BRAF V600E mutation: A case report and review of literature

A 17-year-old female complained of lower extremity pain that progressed to low back pain accompanied by paraparesis. Magnetic resonance imaging revealed a mass in the conus medullaris of the spinal cord at the thoracic spine 11–12 level. The patient underwent resection of the mass. The pathological diagnosis was anaplastic astrocytoma based on the densely proliferating astrocytic tumor cells without necrosis or microvascular proliferation. The patient received chemoradiotherapy with oral temozolomide and a total of 54 Gy of local irradiation, followed by 24 courses of temozolomide as maintenance chemotherapy. The patient survived for 8 years without tumor recurrence following the initial treatment. Genetic analysis of the tumor revealed a BRAF V600E mutation that has not yet been reported in spinal cord high-grade gliomas (HGGs). In recent years, the molecular therapy targeting the BRAF V600E mutation has been applied in clinical practice for several cancer types. Although the frequency in spinal cord HGGs is uncertain, it is necessary to investigate BRAF V600E mutation as a potential therapeutic target in the future.     

Analysis of p53 mutation and expression in pleomorphic xanthoastrocytoma

Pleomorphic xanthoastrocytoma (PXA) is a rare, superficially situated tumor that most frequently occurs in the temporal lobe of young adults and is often associated with seizures. It generally has a relatively favorable prognosis. Prior studies have shown that TP53 mutations may occur in up to 25% of PXAs, suggesting that PXA may have an etiology similar to diffuse astrocytoma rather than pilocytic astrocytoma. In the present study, we performed immunostaining for p53 protein and examined the mutation status of exons 5–8 of the p53 gene in 55 PXAs, 8 of which had undergone one or multiple recurrences. Of 55 primary PXAs, 35 (64%) showed staining in <1% of tumor cells, 15 (27%) in 1–10%, 4 (7%) in 11–50%, and only 1 (2%) in >50%. No significant increase in p53 protein expression was noted in recurrences, even when associated with increased histological anaplasia. We found a TP53 heterozygous mutation in exon 7 in 1 of 47 primary tumors that yielded useable DNA, and in its recurrence 3 years later. This tumor, a grade II PXA, did not show signs of anaplastic transformation at recurrence. Eleven additional recurrences from 7 patients, 5 of which showed signs of histological anaplasia, did not show TP53 mutations in exons 5–8. Based on our data, the p53 mutation appears to be an uncommon (2%) genetic event in PXA formation and does not appear to be involved in tumor progression. Consequently, our findings suggest that the genetic events that underlie PXA formation differ from those involved in diffuse astrocytoma. Electronic Publication     

Cytomegalovirus infection of cerebral astrocytoma in an AIDS patient.

Association of glioma with AIDS is unusual. Cytomegalovirus (CMV) infection of glioma has not been documented in AIDS or non-AIDS patients. We present the case of a 37-year-old homosexual, HIV positive man who had a history of pneumocystis pneumonia and died of disseminated CMV infection and an anaplastic astrocytoma (5 x 5 x 4 cm) of the left temporal lobe. Part of the tumor was severely infected by CMV as demonstrated by immunohistochemical stain. Intranuclear and intracytoplasmic CMV inclusions were present in the cytomegalic cells whose astrocytic nature was identified by immunostain for GFAP. CMV-bearing cells were scattered throughout the astrocytoma but were rarely seen outside the tumor. CMV-bearing endothelial cells were seen in several capillaries within the tumor. Microglial nodules were scattered within the tumor and some contained CMV-infected cells. Many multinucleated giant cells (MNGC) with circularly arranged small nuclei were present in the infected area of the tumor and some showed fusion with cytomegalic cells. MNGC were absent outside the tumor. CMV ependymitis was not seen. The findings suggest that a) astrocytoma cells are permissive to CMV infection, b) that they may be more susceptible to CMV infection and replication than normal brain tissue, and c) the hyperplastic endothelia and abnormal blood brain barrier of the astrocytoma may facilitate the entry of CMV itno the tumor.     

A case of recurrent epilepsy‐associated rosette‐forming glioneuronal tumor with anaplastic transformation in the absence of therapy

Rosette‐forming glioneuronal tumor (RGNT) most commonly occurs adjacent to the fourth ventricle and therefore rarely presents with epilepsy. Recent reports describe RGNT occurrence in other anatomical locations with considerable morphologic and genetic overlap with the epilepsy‐associated dysembryoplastic neuroepithelial tumor (DNET). Examples of RGNT or DNET with anaplastic change are rare, and typically occur in the setting of radiation treatment. We present the case of a 5‐year‐old girl with seizures, who underwent near total resection of a cystic temporal lobe lesion. Pathology showed morphologic and immunohistochemical features of RGNT, albeit with focally overlapping DNET‐like patterns. Resections of residual or recurrent tumor were performed 1 year and 5 years after the initial resection, but no adjuvant radiation or chemotherapy was given. Ten years after the initial resection, surveillance imaging identified new and enhancing nodules, leading to another gross total resection. This specimen showed areas similar to the original tumor, but also high‐grade foci with oligodendroglial morphology, increased cellularity, palisading necrosis, microvascular proliferation, and up to 13 mitotic figures per 10 high power fields. Ancillary studies the status by sequencing showed wild‐type of the isocitrate dehydrogenase 1 (IDH1), IDH2, and human histone 3.3 (H3F3A) genes, and BRAF studies were negative for mutation or rearrangement. Fluorescence in situ hybridization (FISH) showed codeletion of 1p and 19q limited to the high‐grade regions. By immunohistochemistry there was loss of nuclear alpha‐thalassemia mental retardation syndrome, X‐linked (ATRX) expression only in the high‐grade region. Next‐generation sequencing showed an fibroblast growth factor receptor receptor 1 (FGFR1) kinase domain internal tandem duplication in three resection specimens. ATRX mutation in the high‐grade tumor was confirmed by sequencing which showed a frameshift mutation (p.R1427fs), while the apparent 1p/19q‐codeletion by FISH was due to loss of chromosome arm 1p and only partial loss of 19q. Exceptional features of this case include the temporal lobe location, 1p/19q loss by FISH without true whole‐arm codeletion, and anaplastic transformation associated with ATRX mutation without radiation or chemotherapy.     

Expression and regulation of voltage-gated sodium channel β1 subunit protein in human gliosis-associated pathologies

Auxiliary beta1 subunits of voltage-gated sodium channels (NaChs) critically regulate channel activity and may also act as cell adhesion molecules (CAMs). In a recent study we have shown that the expression of beta1 NaCh protein is increased in reactive astrocytes in a rat epilepsy model of mesial temporal lobe epilepsy. The present study was undertaken to examine whether changes of NaCh beta1 subunit protein expression are also associated with structural changes occurring in human reactive astrocytes under different pathological conditions in vivo, as well as in response to changing environmental conditions in vitro. Strong beta1 astroglial immunoreactivity was present in human brain tissue from patients with astrogliosis. The over-expression of beta1 protein in reactive glia was observed in both epilepsy-associated brain pathologies (temporal lobe epilepsy, cortical dysplasia), as well as non-epileptic (cerebral infarction, multiple sclerosis, amyotrophic lateral sclerosis, meningo-encephalitis) disorders. The up-regulation of beta1 subunit protein in astrocytes can be reproduced in vitro. beta1 protein is highly expressed in human astrocytes cultured in the presence of trophic factors, under conditions in which they show morphology similar to the morphology of cells undergoing reactive gliosis. The growth factor-induced overexpression of beta1 protein was abrogated by PD98059, which inhibits the mitogen-activated protein kinase pathway. These findings demonstrate that the expression of NaCh beta1 subunit protein in astrocytes is plastic, and indicate a novel mechanism for modulation of glial function in gliosis-associated pathologies.     

Intracranial Undifferentiated Sarcoma Arising from a Low-Grade Glioma: A Case Report and Literature Review

Undifferentiated sarcomas are rarely identified in the intracranial region. A 23-year-old man was admitted with a chief complaint of headache. Initial magnetic resonance images showed signs of low-grade glioma in the frontal lobe. Stereotactic biopsy was performed, and a diagnosis of diffuse astrocytoma was confirmed. Three months later, the patient presented with a high-grade tumor as seen on imaging studies. He underwent total resection of the tumor and histopathological tests identified an undifferentiated sarcoma. The patient died eight months later due to massive tumor bleeding. To the best of our knowledge, this is the first report of undifferentiated sarcoma arising from low-grade glioma without any chemotherapy or radiotherapy.     

LGI1: a gene involved in epileptogenesis and glioma progression?

The leucine-rich, glioma inactivated gene 1 (LGI1) gene on human chromosome 10q24 was first identified as a candidate tumor suppressor gene for glioma. Surprisingly, mutations in LGI1 were also shown to cause an idiopathic epilepsy syndrome, autosomal dominant lateral temporal lobe epilepsy (ADLTE). LGI1 is one of the only two currently known non-ion channel genes whose mutations cause idiopathic epilepsy in humans. In this review we summarize the current data on structure and function of the LGI1 protein and discuss clinical aspects of ADLTE and their correlation with LGI1. We also propose that the evidence supporting the tumor suppressor role of LGI1 in malignant gliomas is weak and that further work is necessary to establish LGI1 role in glial cells.     

Detection of IDH1 mutations in gliomatosis cerebri, but only in tumors with additional solid component: evidence for molecular subtypes

The current WHO classification of brain tumors defines gliomatosis cerebri (GC) as an extensively infiltrating astrocytic glioma involving at least three cerebral lobes. The relation of GC to diffuse astrocytomas and glioblastoma is uncertain. Due to malignant biological behavior, GC is allotted to WHO grade III. Recent reports showed IDH1 mutations in astrocytic and oligodendroglial tumors WHO grades II and III and in secondary glioblastomas with a frequency of up to 90%, whereas IDH1 mutations occurred in only 5% of primary glioblastomas. Here, we examined the frequency of IDH1 mutations in 35 GC samples by direct sequencing, derived cleaved amplified polymorphic sequence analysis and immunohistochemistry. We identified IDH1 mutations in 10/24 (42%) cases, which also included a solid tumor portion (type 2 GC), but not in 11 “classical” cases without solid tumor mass (type 1 GC). TP53 mutations were revealed in two type 2 GC, but not in any type 1 GC, while combined chromosomal losses of 1p and 19q were not found at all. Our data suggest that GC consists of two histological/molecular subtypes, type 1 being clearly distinct from diffuse astrocytoma, and type 2 sharing features with diffuse astrocytoma.     

Prevention against diffuse spinal cord astrocytoma: can the Notch pathway be a novel treatment target?

This study was designed to investigate whether the Notch pathway is involved in the development of diffuse spinal cord astrocytomas. BALB/c nude mice received injections of CD133+ and CD133- cell suspensions prepared using human recurrent diffuse spinal cord astrocytoma tissue through administration into the right parietal lobe. After 7–11 weeks, magnetic resonance imaging was performed weekly. Xenografts were observed on the surfaces of the brains of mice receiving the CD133+ cell suspension, and Notch-immunopositive expression was observed in the xenografts. By contrast, no xenografts appeared in the identical position on the surfaces of the brains of mice receiving the CD133- cell suspension, and Notch-immunopositive expression was hardly detected either. Hematoxylin-eosin staining and immunohistochemical staining revealed xenografts on the convex surfaces of the brains of mice that underwent CD133+ astrocytoma transplantation. Some sporadic astroglioma cells showed pseudopodium-like structures, which extended into the cerebral white matter. However, it should be emphasized that the subcortex xenograft with Notch-immunopositive expression was found in the fourth mouse received injection of CD133- astrocytoma cells. However, these findings suggest that the Notch pathway plays an important role in the formation of astrocytomas, and can be considered a novel treatment target for diffuse spinal cord astrocytoma.     

The CD34 epitope is expressed in neoplastic and malformative lesions associated with chronic, focal epilepsies

The etiology and pathogenesis of complex focal lesions associated with chronic, intractable epilepsy are largely unknown. Some data indicate that malformative changes of the central nervous system may preceed the development of gangliogliomas and other epilepsy-associated neoplasms. In the present immunhistochemical study, we have examined epilepsy-associated lesions for CD34, a stem cell marker transiently expressed during early neurulation. Surprisingly, most tissue samples from patients with chronic epilepsy (n = 262) revealed neural cells immunoreactive for CD34. Prominent immunoreactivity was detected in gangliogliomas (74%), low-grade astrocytomas (62%) and oligodendrogliomas (59%). Only 52% of non-neoplastic, malformative pathologies, such as glio-neuronal hamartias or hamartomas showed solitary or small clusters of CD34-immunoreactive cells. None of the adult control tissues (n = 22), none of the specimens obtained from the developing human brain (n = 44) and none of those tumor samples from patients without epilepsy (n = 63) contained CD34-immunoreactive neural cells. However, a malignant teratoma with microscopic features of early neural differentiation displayed a focal CD34-immunoreactive staining pattern. The majority of CD34-immunoreactive cells co-localized with S-100 protein and a small subpopulation was also immunoreactive for neuronal antigens. CD34 may, thus, represent a valuable marker for the diagnostic evaluation of neoplastic and/or malformative pathological changes in epilepsy patients. The CD34 immunoreactivity of these lesions indicates an origin from dysplastic or atypically differentiated neural precursors. Further studies may elucidate the functional significance of CD34 expression during the pathogenesis of epilepsy-related focal lesions as well as during neurogenesis. Received: 1 September 1998 / Accepted: 21 October 1998