ZFTA::RELA fusion in a distinct liposarcoma morphologically overlapping with chondroid lipoma.

Chondroid lipoma is a rare benign adipose tumor characterized by a recurrent ZFTA::MRTFB fusion. Herein, we report an unusual liposarcoma that partly exhibited overlapping features with those of chondroid lipoma and harbored a ZFTA::RELA fusion. A 59-year-old man presented with a shoulder mass that had existed for approximately 8 years and with increasing pain due to a pelvic mass. The 5.8-cm resected shoulder tumor partly consisted of nests and strands of variably lipogenic epithelioid cells within a hyalinized or focally chondromyxoid stroma, indistinguishable from chondroid lipoma. The histological pattern gradually transitioned to highly cellular, stroma-poor, diffuse sheets of cells with greater nuclear atypia and mitotic activity. Vascular invasion and necrosis were present. The metastatic pelvic tumor revealed a similar histology. Despite multimodal treatment, the patient developed multiple bone metastases and succumbed to the disease 14 months after presentation. Targeted RNA sequencing identified an in-frame ZFTA (exon 3)::RELA (exon 2) fusion, which was confirmed by reverse transcription-polymerase chain reaction, Sanger sequencing, and break-apart fluorescent in situ hybridization assays. The tumor showed a different histology from that of ependymoma, no brain involvement, and no match with any sarcoma types or ZFTA::RELA-positive ependymomas according to DNA methylation analysis. p65 and L1CAM were diffusely expressed, and a CDKN2A/B deletion was present. This is the first report of an extra-central nervous system tumor with a ZFTA::RELA fusion. The tumor partly displayed an overlapping histology with that of chondroid lipoma, suggesting that it may represent a hitherto undescribed malignant chondroid lipoma with an alternative ZFTA fusion.

Keratin-positive fibrotic extraskeletal myxoid chondrosarcoma: a close mimic of myoepithelial tumour.

AIMS: Extraskeletal myxoid chondrosarcoma (EMC) is a rare form of adult sarcoma with distinct histology and NR4A3 gene fusion. Immunohistochemically, EMCs are variably positive for S100 protein and neuroendocrine markers. Unlike histologically similar soft-tissue myoepithelial tumours, keratin expression is rare. Prompted by two recent EMC cases with diffuse keratin expression, we investigated the expression of epithelial markers in a molecularly confirmed cohort of EMC and identified two additional similar cases. METHODS AND RESULTS: Four keratin-positive EMCs occurred in one man and three women aged 46-59 years. All tumours displayed nonclassic histology with prominent stromal fibrosis, and keratin AE1/AE3 was expressed either diffusely (N = 2) or focally (N = 2). In one tumour, keratin expression was limited to the sclerotic area. All tumours coexpressed epithelial membrane antigen and two additionally expressed S100 protein or glial fibrillary acidic protein. All tumours harboured NR4A3 fusions, including TAF15::NR4A3 (N = 1) and EWSR1::NR4A3 (N = 3). Two cases were initially considered as most consistent with myoepithelial tumours based on widespread stromal fibrosis and keratin expression. DNA methylation analysis classified two tumours tested as EMCs. CONCLUSIONS: We identified a small subset of EMCs characterised by keratin expression and prominent stromal fibrosis. This histological pattern must be recognised in the differential diagnosis of myoepithelial tumours because misclassification may lead to the erroneous prediction of tumour behaviour and may alter patient management. NR4A3 genetic analysis should be considered even in the face of keratin expression and prominent stromal fibrosis.

Systemic inflammation caused by an intracranial mesenchymal tumor with a EWSR1::CREM fusion presenting associated with IL-6/STAT3 signaling.

Pediatric neoplastic diseases account for about 10% of cases of fever of unknown origin (FUO), and most neoplastic disease cases are leukemia, lymphoma, and neuroblastoma. Brain tumors are rarely reported as the cause of FUO, although craniopharyngioma, metastatic brain tumor, and Castleman's disease have been reported. We report a case of intracranial mesenchymal tumor (IMT) with a FET:CREB fusion gene, which had inflammatory phenotype without neurological signs. A 10-year-old girl was admitted with a 2-month history of intermittent fever and headache, whereas her past history as well as her family history lacked special events. Sepsis work-up showed no pathological organism, and empirical antibiotic therapy was not effective. Bone marrow examination showed a negative result. Cerebrospinal fluid examination showed elevated protein as well as cell counts, and head magnaetic resonance imaging showed a hypervascular mass lesion with contrast enhancement in the left cerebellar hemisphere. The patient underwent tumor excision, which made the intermittent fever disappear. Pathological examinations resembled those of classic angiomatoid fibrous histiocytoma (AFH), but the morphological features were distinct from the AFH myxoid variant; then we performed break-apart fluorescence in situ hybridization and confirmed the tumor harbored the rare EWSR1::CREM fusion gene (Ewing sarcoma breakpoint region 1 gene (EWSR1) and cAMP response element binding (CREB) family gene). Consequently, we diagnosed the condition as IMT with EWSR1::CREM fusion. Elevated serum concentration of interleukin 6 (IL-6) was normalized after tumor resection, which suggested the fever could be caused by tumor-derived IL-6. This is the first case of IMT with EWSR1::CREM fusion that showed paraneoplastic symptoms associated with the IL-6/signal transducer and activator of transcription 3 (STAT3) signaling pathway. Although brain tumors are rarely diagnosed as a responsible disease for FUO, they should be considered as a cause of unknown fever even in the absence of abnormal neurological findings.

Molecular and expressional characterization of tumor heterogeneity in pulmonary carcinosarcoma.

The genetic concordance and heterogeneity of the two components of pulmonary carcinosarcoma (PCS), carcinoma, and sarcoma, have not been fully elucidated because of its rare occurrence. We performed targeted sequencing of the carcinoma and sarcoma components of four PCSs to identify genetic similarities and differences. Formalin-fixed paraffin-embedded tissue samples were macroscopically or microscopically dissected. DNA was extracted from each component, and genetic alterations were analyzed separately. Moreover, we performed RNA-seq analysis on both components of one PCS to compare differences in gene expression profiles. The carcinoma part consisted of adenocarcinoma in two cases, squamous cell carcinoma in one, and adenosquamous carcinoma in the last. TP53 mutation was observed in three samples from the trunk, although it was detected only in the sarcoma part in one case. No specific driver gene mutation was observed; however, KRAS mutations were observed in one case in the trunk. RNA-seq analysis revealed that the rhabdomyosarcoma component expressed various genes related to muscle development, whereas the carcinoma component did not; and that gene expression overall was completely different between the two components. Our study revealed that the two different components of PCS shared common gene mutations in most cases. Although gene expression was different among components, if driver genes such as KRAS were detected in PCS, molecular targeted therapy could be beneficial even when the tumor contains a sarcoma component.

An autopsy case of granulomatous amebic encephalitis caused by Balamuthia mandrillaris involving prior amebic dermatitis.

An 82-year-old man, who was healthy and had worked as a farmer, experienced worsening neurological symptoms over a seven-month period, which eventually caused his death. Multiple fluctuating brain lesions were detected radiographically. Clinically, sarcoidosis was ranked high among the differential diagnoses because of the presence of skin lesions showing granulomatous inflammation, confirmed by biopsy. The patient's cerebrospinal fluid was also examined, but no definitive diagnosis was made while he was alive. An autopsy revealed multiple granulomatous amebic encephalitis lesions in the brain. Genetic and immunohistochemical analyses identified Balamuthia (B.) mandrillaris, a free-living ameba, which resides in soil and fresh water, as the causative organism. A retrospective examination revealed B. mandrillaris in the biopsied skin as well as cerebrospinal fluid, strongly suggesting that the ameba had spread into the brain percutaneously. Few studies have detailed the cutaneous pathology of B. mandrillaris infections. In general, granulomatous amebic encephalitis is extremely difficult to diagnose without autopsy, but the present case provides a clue that could allow similar cases to be diagnosed earlier; that is, the presence of skin lesions.

High-grade neuroepithelial tumor with BCL6 corepressor-alteration presenting pathological and radiological calcification: A case report.

A 5-year-old girl presented with headache and vomiting. Head computed tomography and magnetic resonance imaging showed a right frontal lobe tumor with marked calcification. The patient underwent resection surgery with suspicion of anaplastic ependymoma, and the tumor was gross totally removed. Pathological examination revealed areas of dense tumor cells with a high nucleocytoplasmic ratio and myxoid areas consisting of tumor cells with a round-shaped nucleus and eosinophilic cytoplasm. Perivascular pseudorosette, necrosis, circumscribed growth, and microcalcification were also observed. Immunohistochemistry demonstrated negative staining for glial fibrillary protein and epithelial membrane antigen. Diagnosis of a high-grade neuroepithelial tumor (HGNET) with BCL6 corepressor (BCOR) alteration was made based on pathological findings and internal tandem duplication in the exon 15 of BCOR. Although calcification on radiological and pathological examination is not typical, it would be essential to recognize that calcification could appear in HGNET-BCOR.

The influence of the long-term chemical activation of the nuclear receptor pregnane X receptor (PXR) on liver carcinogenesis in mice.

Pregnane X receptor (PXR) and constitutive androstane receptor (CAR) are nuclear receptors that are highly expressed in the liver and activated by numerous chemicals. While CAR activation by its activators, such as phenobarbital (PB), induces hepatocyte proliferation and liver carcinogenesis in rodents, it remains unclear whether PXR activation drives liver cancer. To investigate the influence of PXR activation on liver carcinogenesis, we treated mice with the PXR activator pregnenolone 16α-carbonitrile (PCN) with or without PB following tumor initiation with diethylnitrosamine (DEN). After 20 weeks of treatment, preneoplastic lesions detected by immunostaining with an anti-KRT8/18 antibody were observed in PB-treated but not PCN-treated mice, and PCN cotreatment augmented the formation of preneoplastic lesions by PB. After 35 weeks of treatment, macroscopic observations indicated that PB-treated and PB/PCN-cotreated mice had increased numbers of liver tumors compared to control and PCN-treated mice. In the pathological analyses of liver sections, all the mice in the PB and PB/PCN groups developed carcinoma and/or eosinophilic adenoma, but in the PB/PCN group, the multiplicity of carcinoma and eosinophilic adenoma was significantly reduced and the size of carcinoma showed a tendency to decrease. No mouse in the control or PCN-treated group developed such tumors. Differentially expressed gene (DEG) and gene set enrichment analyses in combination with RNA sequencing suggested the increased expression of genes related to epithelial-mesenchymal transition (EMT) in mice cotreated with PCN and PB compared to those treated with PB alone. Changes in the hepatic mRNA levels of epithelial marker genes supported the results of the transcriptome analyses. In conclusion, the present results suggest that PXR activation does not promote hepatocarcinogenesis in contrast to CAR and rather attenuates CAR-mediated liver cancer development by suppressing the EMT of liver cancer cells in rodents.

Pineoblastoma segregates into molecular sub-groups with distinct clinico-pathologic features: a Rare Brain Tumor Consortium registry study.

Pineoblastomas (PBs) are rare, aggressive pediatric brain tumors of the pineal gland with modest overall survival despite intensive therapy. We sought to define the clinical and molecular spectra of PB to inform new treatment approaches for this orphan cancer. Tumor, blood, and clinical data from 91 patients with PB or supratentorial primitive neuroectodermal tumor (sPNETs/CNS-PNETs), and 2 pineal parenchymal tumors of intermediate differentiation (PPTIDs) were collected from 29 centres in the Rare Brain Tumor Consortium. We used global DNA methylation profiling to define a core group of PB from 72/93 cases, which were delineated into five molecular sub-groups. Copy number, whole exome and targeted sequencing, and miRNA expression analyses were used to evaluate the clinico-pathologic significance of each sub-group. Tumors designated as group 1 and 2 almost exclusively exhibited deleterious homozygous loss-of-function alterations in miRNA biogenesis genes (DICER1, DROSHA, and DGCR8) in 62 and 100% of group 1 and 2 tumors, respectively. Recurrent alterations of the oncogenic MYC-miR-17/92-RB1 pathway were observed in the RB and MYC sub-group, respectively, characterized by RB1 loss with gain of miR-17/92, and recurrent gain or amplification of MYC. PB sub-groups exhibited distinct clinical features: group 1-3 arose in older children (median ages 5.2-14.0 years) and had intermediate to excellent survival (5-year OS of 68.0-100%), while Group RB and MYC PB patients were much younger (median age 1.3-1.4 years) with dismal survival (5-year OS 37.5% and 28.6%, respectively). We identified age < 3 years at diagnosis, metastatic disease, omission of upfront radiation, and chr 16q loss as significant negative prognostic factors across all PBs. Our findings demonstrate that PB exhibits substantial molecular heterogeneity with sub-group-associated clinical phenotypes and survival. In addition to revealing novel biology and therapeutics, molecular sub-grouping of PB can be exploited to reduce treatment intensity for patients with favorable biology tumors.

Oligodendroglioma showing pleomorphic xanthoastrocytoma-like perivascular microlesion: With IDH1, TERT promoter mutation and 1p/19q codeletion detected in both components.

We report a histological and genetic study of concurrent oligodendroglioma and a microscopic pleomorphic xanthoastrocytoma (PXA)-like lesion in a 48-year-old male. He presented with generalized seizure, and magnetic resonance imaging revealed a nonenhanced left frontal lobe mass suggesting low-grade glioma. The patient underwent craniotomy and tumor resection. Histopathological examination of the surgical specimen showed an oligodendroglioma with a PXA-like element; the latter measured 0.9 mm and occupied a Virchow-Robin space of the superficial cortex. The whole tumor had no elevated mitotic activity, microvascular proliferation or necrosis. Each component was immunohistochemically isocitrate dehydrogenase (IDH1)-R132H positive, p53 negative and ATRX positive. Genetic analyses clarified identical IDH1 G395A mutation, promoter C228T mutation and 1p/19q codeletion in both elements. Careful integration of histology and telomerase reverse transcriptase (TERT) molecular parameters revealed that this case was an oligodendroglioma showing PXA-like features, rather than a collision tumor. This case provides further insights into the gliomagenesis.

A rare case of BRAF V600E-mutated epithelioid glioblastoma with a sarcomatous component.

Epithelioid glioblastoma is a rare subtype of glioblastoma, but the coexistence of a sarcomatous component is even rarer. An 80-year-old woman was admitted to our hospital with somnolence. Magnetic resonance imaging revealed a cystic lesion with a solid component in the left temporal-parietal lobe. Histopathological examination of the resected tumor revealed three components; namely, typical glioblastoma, sarcomatous and epithelioid components at a ratio of about 5:3:2. All components were immunohistochemically positive for vimentin and mutated BRAF (V600E) and showed focal expression of glial fibrillary acidic protein and cytokeratin AE1/AE3, but they were negative for isocitrate dehydrogenase 1. Genetic analysis revealed that both the sarcomatous and epithelioid components harbored BRAF T1799A (V600E) mutation and homozygous deletion of cyclin-dependent kinase inhibitor 2A/B. We diagnosed this tumor as epithelial glioblastoma with a sarcomatous component. Our results indicate that even when the epithelial component is not dominant, immunohistochemical and genetic investigation of BRAF mutations is useful for the diagnosis of glioblastoma subtypes. In particular, although the prognosis of epithelial glioblastoma is poor, potentially effective targeted therapies for BRAF V600E-mutated tumors are available.

Significance of RAS mutations in pulmonary metastases of patients with colorectal cancer.

BACKGROUND: RAS/BRAF mutations of colorectal cancer (CRC) play a crucial role in carcinogenesis and cancer progression and need to be considered for the therapeutic strategy choice. We used next-generation-sequencing (NGS) technology to assess RAS/BRAF mutation differences between primary CRC and corresponding pulmonary metastases (PMs). METHODS: We examined the mutation statuses of the KRAS 12/13/61/146, NRAS 12/13/61/146, and BRAF 600 codons in genomic DNA from fresh-frozen or formalin-fixed paraffin-embedded tissues derived from 34 primary lesions and 52 corresponding PMs from 36 patients with CRC. RESULTS: We found RAS mutations in 76% (26/34) of primary CRC lesions and in 86% (31/36) of PMs. While 27% (7/26) of the primary CRC RAS mutations were heterogeneous, all the RAS mutations in PMs were homogeneous. Of the mutations in PMs, 71% (22/31) were KRAS G>A transitions, of which 82% (18/22) were KRAS G12D or G13D. The RAS mutation discordance between primary tumors and PMs was 12.1% (4/33). RAS mutations with the same genotyping were detected in all synchronous and metachronous PMs from 9 patients. We found no BRAF mutations in either primary or pulmonary tissues. CONCLUSION: Our NGS analysis suggests that RAS mutations of PM of patients with CRC are more common than initially thought. The presence of KRAS mutations in CRC specimens, especially G12D or G13D mutations, seems to promote PM formation.

Multiplex ligation-dependent probe amplification analysis is useful for detecting a copy number gain of the FGFR1 tyrosine kinase domain in dysembryoplastic neuroepithelial tumors.

PURPOSE: Dysembryoplastic neuroepithelial tumors (DNTs) are slow-growing glioneuronal tumors, and their genetic backgrounds are getting unveiled. Recently, fibroblast growth factor receptor 1 internal tandem duplication (FGFR1-ITD) of the tyrosine kinase domain (TKD) has been demonstrated by whole-genome sequencing. METHODS AND RESULTS: Here, we analyzed 22 DNTs using multiplex ligation-dependent probe amplification (MLPA) with formalin-fixed paraffin-embedded specimens and found a copy number gain in TKD of FGFR1 (13 cases, 59%), which suggested the presence of FGFR1-ITD. Another 5 DNTs harbored FGFR1 hot spot mutations including a double mutant case, and FGFR1 alterations were detected in 18 DNTs (82%). The BRAF V600E mutation, another important mutation in DNTs, was not observed. CONCLUSIONS: With recent findings of less frequent or absent FGFR1-ITD in pilocytic astrocytomas or rosette-forming glioneuronal tumors, the analysis of FGFR1 aberrations, especially FGFR1-ITD, was suggested to be helpful to discriminate DNTs from their histological mimics.

An epilepsy-associated glioneuronal tumor with mixed morphology harboring FGFR1 mutation.

Glioneuronal tumor (GNT) is a rare central nervous system neoplasm composed of glial and neuronal components. Making the specific diagnosis of GNT can be challenging due to histopathological and genetical similarities among some GNTs and low-grade gliomas. We report a case of GNT with rosette-forming glioneuronal tumor, dysembryoplastic neuroepithelial tumor, and pilocytic astrocytoma-like morphology harboring FGFR1 mutation. A 16-year-old female presented with absence seizures. Magnetic resonance imaging revealed a right temporal lobe mass with multinodular enhancement by gadolinium administration. The tumor was mostly composed of oligodendrocyte-like cells (OLCs) with variable perinuclear haloes. Abundant Rosenthal fibers and eosinophilic granular bodies were identified. Neither mitotic figures nor areas of necrosis were seen. Focal neurocytic rosette features, involving ring-like arrays of OLCs around eosinophilic cores, were observed. Direct sequencing showed a missense mutation in FGFR1 K656E, whereas FGFR1 N546K, PIK3CA, and BRAF V600E were intact. KIAA1549-BRAF fusion was not detected by fluorescence in situ hybridization analysis.

[CA19-9 Producing Mixed Invasive Mucinous and Non-mucinous Adenocarcinoma;Report of a Case].

A 66-year-old woman was referred to our hospital due to the abnormal shadow on chest X-ray. Computed tomography(CT) scan revealed a mass in the lower lobe of the right lung and the serum CA19-9 level was 1,600 U/ml. Under the diagnosis of adenocarcinoma by bronchoscopic brushing cytology, right lower lobectomy with mediastinal lymph node dissection was performed. Histopathological examination showed mixed invasive mucinous and non-mucinous adenocarcinoma [World Health Organization (WHO) 8th] of stage IA3 with T1cN0M0[ Union for International Cancer Control( UICC) 8th]. Immunohistochemically, the tumor cells were stained positively for CA19-9. Postoperative course was uneventful and the CA19-9 level decreased to 35.5 U/ml 2 months after operation.

Gliosarcoma with primitive neuronal, chondroid, osteoid and ependymal elements.

A 51-year-old man presented with a 2-week history of malaise. MRI revealed a large solid and cystic lesion with ring enhancement measuring 6.5 cm in diameter in the right frontal lobe. Histologically, the tumor consisted of various components: diffuse growth of atypical astrocytic cells consistent with glioblastoma, fascicular proliferation of atypical spindle cells such as fibrosarcoma, clusters of primitive neuronal cells, and foci of ependymal cells. The sarcomatous component also focally exhibited chondroid and osteoid differentiation. Immunohistochemically, tumor cells in the primitive neuronal component were immunoreactive for synaptophysin and CD56. The spindle cells were immunopositive for Slug and Twist, regulators of epithelial-mesenchymal transition. Direct DNA sequencing demonstrated C228T mutation in the TERT promoter in astrocytic, sarcomatous and primitive neuronal components, suggesting their identical origin. Although a few cases of gliosarcoma with primitive neuronal differentiation have previously been described, the finding that neuronal, glial and sarcomatous components share an identical mutation of the TERT promoter has not been reported. The tumor recurred at the original site 11 months after the first surgery. Interestingly, the recurrent tumor was composed exclusively of a glioblastomatous component, unlike past cases of recurrent gliosarcoma.

Brainstem astroblastoma with MN1 translocation.

Astroblastoma is a rare glial neoplasm that occurs mostly in the cerebral hemisphere of children, adolescents and young adults. Although astroblastic perivascular pseudorosettes are unique histopathology of this neoplasm, diagnosis is usually challenging. Recently, it was discovered that the meningioma 1 gene (MN1)-altered pediatric central nervous system high-grade neuroepithelial tumors are actually astroblastomas. This case report presents a rare brainstem astroblastoma, with an unusual immunoprofile: negative for glial fibrillary acidic protein and oligodendrocyte transcription factor 2, but with a robust expression of pancytokeratin and epithelial membrane antigen. The diagnosis was confirmed based on the detection of MN1 rearrangement in a fluorescence in situ hybridization study, in addition to typical histopathology. Here we discuss the diagnostic pitfalls and unclear grading system along with a literature review.

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.

Anaplastic ganglioglioma with epithelioid cell components.

A 40-year-old man was admitted to our hospital because of disorientation and mild left-sided weakness. Radiological examination revealed a solid and cystic tumor in the right temporal lobe, and total resection was performed. Histologically, the tumor was composed mainly of low-grade gangiloglioma and had some high-grade glial components with focal necrosis and microvascular proliferations. In the high-grade component, there were epithelioid cells with round cytoplasm and eccentric nuclei. The high-grade area with epithelioid cells was intermingled within the low-grade area, which suggests that epithelioid cells were an anaplastic transformation of ganglioglioma. The epithelioid cells were histologically similar to neoplastic cells of epithelioid glioblastoma (E-GBM), a rare aggressive variant of isocitric dehydrogenase wild-type glioblastoma. A BRAF V600E mutation, frequently observed in E-GBM, was detected in both the ganglioglioma and epithelioid cell components. The epithelioid cells were mitotically active, which suggests that if the surgery was delayed, the histological appearance might have eventually evolved into E-GBM. Indeed, a case of pleomorphic xanthoastrocytoma which transformed into E-GBM after a long latency was reported elsewhere. This is the first report to describe focal epithelioid cells in anaplastic ganglioglioma.

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.