Epithelioid glioblastoma diagnosed 70 years after craniofacial radiotherapy

The authors report a rare case of most likely radiation-induced glioma (RIG) with epithelioid features and the presence of molecular features consistent with RIG. This occurred 70 years after craniofacial brachytherapy. Such a late development of radiation-induced glioblastoma (RIGBM) and the advanced age of presentation for an epithelioid glioblastoma are both unique in the literature. Despite not receiving the full course of adjuvant chemotherapy after surgery and radiotherapy, the patient displayed no signs of recurrence during a 5-year follow-up. RIGBM should be further studied to reveal potential unique clinical and molecular characteristics, as well as to better predict survival and treatment response.

A rare occurrence of an epithelioid glioblastoma in a pediatric patient: case report and review of the literature

Epithelioid glioblastoma is a rare tumor in the pediatric population. We present a case report of a 5-year-old boy found to have a large right frontotemporal epithelioid glioblastoma. The patient was treated with maximal safe resection followed by craniospinal radiation. He has now reached 5-year survival and does not have tumor progression. Given the rarity of epithelioid glioblastoma in the pediatric population, the literature surrounding the diagnosis and treatment options for these tumors is reviewed.

Abnormal Schwannoma-like Growth of multiple, multifocal BRAF V600E-positive Glioblastoma in the Interior Acoustic Canal with Leptomeningeal Infiltration: a case report

Background

Glioblastoma belongs to the most common and most aggressive tumor entity of the central nervous system with a poor prognosis of only few months. Once manifested, it grows fast and diffusely by infiltrating the surrounding brain parenchyma. Despite its aggressive behavior, glioblastoma rarely presents with multiple lesions and metastasis to intra- and extracranial tissues. Therefore, metastasized, multiple glioblastoma is limited to case reports. Our case describes an atypical primary bilateral manifestation of BRAF V600E-positive epithelioid glioblastoma with rapid metastasis and meningeosis glioblastoma while under adjuvant chemoradiotherapy.

Case presentation

A 60-year-old Caucasian male patient presented with a seizure and numbness in his left arm. He was diagnosed with an abnormal primary bilateral manifestation of multiple, multifocal BRAF V600E-positive and isocitrate dehydrogenase (IDH) wild-type intracranial epithelioid glioblastoma with O⁶-methylguanine-DNA methyltransferase methylation (MGMT) at 12%. While being under the adjuvant chemoradiotherapy with temozolomide, the patient developed left-sided facial nerve weakness and hearing loss, dysarthria, and severe gait instability. Cranial magnetic resonance imaging showed that glioblastoma lesions advanced rapidly with a schwannoma-like growth pattern by invading the left internal acoustic meatus, adjacent cranial nerves, and leptomeninges. A lumbar puncture confirmed meningeosis glioblastoma. Four months after the initial diagnosis of glioblastoma, the patient died from the complications of the fast and diffuse metastasis.

Conclusions

Glioblastoma rarely presents with metastases despite its aggressive and rapidly growing nature. Our case should increase awareness of symptom tracking in patients with glioblastoma to intervene early and efficiently. Moreover, refractory therapies for glioblastoma should underline the importance of personalized medicine.

Pleomorphic xanthoastrocytoma is a heterogeneous entity with pTERT mutations prognosticating shorter survival

Pleomorphic xanthoastrocytoma (PXA) in its classic manifestation exhibits distinct morphological features and is assigned to CNS WHO grade 2 or grade 3. Distinction from glioblastoma variants and lower grade glial and glioneuronal tumors is a common diagnostic challenge. We compared a morphologically defined set of PXA (histPXA) with an independent set, defined by DNA methylation analysis (mcPXA). HistPXA encompassed 144 tumors all subjected to DNA methylation array analysis. Sixty-two histPXA matched to the methylation class mcPXA. These were combined with the cases that showed the mcPXA signature but had received a histopathological diagnosis other than PXA. This cohort constituted a set of 220 mcPXA. Molecular and clinical parameters were analyzed in these groups. Morphological parameters were analyzed in a subset of tumors with FFPE tissue available. HistPXA revealed considerable heterogeneity in regard to methylation classes, with methylation classes glioblastoma and ganglioglioma being the most frequent mismatches. Similarly, the mcPXA cohort contained tumors of diverse histological diagnoses, with glioblastoma constituting the most frequent mismatch. Subsequent analyses demonstrated the presence of canonical pTERT mutations to be associated with unfavorable prognosis among mcPXA. Based on these data, we consider the tumor type PXA to be histologically more varied than previously assumed. Histological approach to diagnosis will predominantly identify cases with the established archetypical morphology. DNA methylation analysis includes additional tumors in the tumor class PXA that share similar DNA methylation profile but lack the typical morphology of a PXA. DNA methylation analysis also assist in separating other tumor types with morphologic overlap to PXA. Our data suggest the presence of canonical pTERT mutations as a robust indicator for poor prognosis in methylation class PXA.

Clinicopathological characteristics and treatment outcomes of epithelioid glioblastoma

Epithelioid glioblastoma is a new variant of glioblastoma that has been recently recognized in the 2016 WHO classification of brain tumors. Given the rarity of epithelioid glioblastoma, the clinical characteristics, pathological features, radiological findings, and treatment outcomes are still not well characterized. Therefore, we identified eighty-four epithelioid glioblastoma cases to investigate these characteristics and identify the possible prognostic factors of survival. There were 55 male and 29 female patients with a mean age of 33.6 years. Headache (77.3%) was the most common clinical symptom, and other common symptoms included nausea or vomiting (34%), dizziness (20.5%), seizures (13.6%), and limb weakness (13.6%). Most lesions (88.1%) were located in cerebral lobes, especially in the frontal lobe and temporal lobe. One hundred percent of the patients were IDH1 wild-type (75/75) and INI-1 positive (58/58), and 57.3% (47/82) of patients harbored BRAF^V600E mutation. The median overall survival (OS) of all patients was 10.5 months. Patients who received chemotherapy (p = 0.006) or radiotherapy (p = 0.022) had a longer survival than patients who did not. In addition, the K-M curve showed that the BRAF^V600E mutation status was not associated with survival (p = 0.724). These findings may assist clinicians with better understanding and management of epithelioid glioblastoma.

Analysis of 24 cases of epithelioid glioblastoma: Experience from a tertiary centre of North India

BACKGROUND

Epithelioid glioblastoma (eGB) is a recently recognized and a rare variant of glioblastoma. This study aimed to describe the clinical, histological and immunohistochemical spectrum and outcome of eGB from a tertiary care hospital in north India.

MATERIALS AND METHODS

Twenty four cases of eGB diagnosed over past 10 years were reviewed with detailed morphological and immunohistochemical analysis (GFAP, EMA, Vimentin, Myogenin, INI-1, Cytokeratin, Synaptophysin, CD99, S100, MelanA, IDH1, ATRX, p16, EZH2, Ki-67, and BRAF V600E mutant antibody).

RESULT

The mean age was 29.9 years (3-54 years), with equal male and female patients. All had supratentorial tumor. All cases showed epithelioid cells in sheets; however, focal spindling (7 cases, 29.2%), grouping/nesting (6 cases, 25%) and papillary configuration (5 cases, 20.8%) were also noted. All showed microvascular proliferation (MVP) and all except one demonstrated areas of necrosis. INI1 was retained in all cases, while 2 showed patchy loss. EZH2 overexpression (>25%) was observed in 4 cases, while 5 cases showed loss of p16 expression. BRAF V600E mutant protein expression was seen in 12/23 (52.2%) cases. Outcome was available in 8 cases, out of which 6 (75%) experienced recurrence. The median survival was 25.5 months. Cases with tumor infiltrating lymphocytes had a better outcome.

CONCLUSION

eGB is a distinct variant of glioblastoma which has predilection towards younger age group. It shows high percentage of BRAF V600E mutation and a subset of it shows longer survival. Cases with presence of tumor infiltrating lymphocytes are associated with better outcome.

Additional genetic alterations in BRAF-mutant gliomas correlate with histologic diagnoses

INTRODUCTION

Recently, the term "Diffuse glioma, BRAF V600E-mutant" has been recommended for IDH-wildtype gliomas with BRAF p.V600E mutation and without CDKN2A/B deletion. However, additional alterations in gliomas that coexist with BRAF-mutations are poorly defined.

METHODS

We analyzed next-generation sequencing results in 315 cancer-associated genes for 372 gliomas from our institution (2010 to 2017). In addition, we reviewed IDH-WT gliomas with mutation and copy-number alterations available in cBioPortal, to further characterize BRAF-mutant gliomas.

RESULTS

Seventeen (4.6%) showed BRAF mutations. Tumor types included 8 glioblastomas, 2 epithelioid glioblastomas (E-GBM), 2 pleomorphic xanthoastrocytomas (PXA), 1 anaplastic oligodendroglioma, 1 diffuse astrocytoma, and 3 pilocytic astrocytomas. Fifty-three percent (53%) of cases exhibited BRAF-alterations other than p.V600E. The majority of the tumors were localized in the temporal lobe (52.9%). In addition to BRAF mutations, glioblastomas showed concomitant mutations in TP53 (3/8), CDKN2A/B-loss (6/8), TERT-promoter (6/8), and/or PTEN (5/8). Both E-GBMs and PXAs showed CDKN2A/B-loss and BRAF p.V600E with absence of TERTp, TP53, and PTEN mutations. Similar findings were observed in BRAF-mutant infiltrating gliomas from cBioPortal.

CONCLUSIONS

Knowledge of additional alterations that co-occur with BRAF-mutations in gliomas may improve diagnosis and help identify patients that could benefit from targeted therapies. Furthermore, we provide examples of two patients whose tumors responded to BRAF pathway inhibitors, arguing in favor of these therapies in patients with BRAF-mutant gliomas.

Epithelioid glioblastoma presenting as multicentric glioma: A case report and review of the literature

Background:

Epithelioid glioblastoma is a rare aggressive variant of glioblastoma multiforme (GBM), which was formally recognized by the World Health Organization classification of the central nervous system in 2016. Clinically, epithelioid GBMs are characterized by aggressive features, such as metastases and cerebrospinal fluid dissemination, and an extremely poor prognosis. A rare case of epithelioid GBM that was discovered as a multicentric glioma with different histopathology is reported.

Case Description:

A 78-year-old man was admitted to our hospital with mild motor weakness of the right leg. Neuroimaging showed small masses in the left frontal and parietal lobes on magnetic resonance imaging. The abnormal lesion had been increasing rapidly for 3 weeks, and a new lesion appeared in the frontal lobe. 11C-methionine positron emission tomography (PET) showed abnormal uptake corresponding to the lesion. To reach a definitive diagnosis, surgical excision of the right frontal mass lesion was performed. Histological findings showed diffuse astrocytoma. Only radiotherapy was planned, but the left frontal and parietal tumors progressed further within a short period. Therefore, it was thought that these tumors were GBM, and a biopsy of the left parietal tumor was performed. The histological diagnosis was epithelioid GBM. Immunohistochemistry showed that most tumor cells were negatively stained for p53 and isocitrate dehydrogenase 1. BRAF V600E mutations were not identified, but TERT promoter mutations were identified. Immediately after surgery, the patient was given chemotherapy using temozolomide, extended local radiotherapy and then bevacizumab. After 6 months, he showed no signs of recurrence.

Conclusion:

Epithelioid GBM is one of the rarest morphologic subtypes of GBM and has a strongly infiltrative and aggressive nature. Therefore, careful identification of preoperative imaging studies and detailed evaluation of genetic studies are necessary to select the appropriate treatment for epithelioid GBM.

Dramatic response of BRAF V600E-mutant epithelioid glioblastoma to combination therapy with BRAF and MEK inhibitor: establishment and xenograft of a cell line to predict clinical efficacy

Epithelioid glioblastoma is a rare aggressive variant of glioblastoma (GBM) characterized by a dismal prognosis of about 6 months and frequent leptomeningeal dissemination. A recent study has revealed that 50% of epithelioid GBMs harbor three genetic alterations - BRAF V600E mutation, TERT promoter mutations, and homozygous deletions of CDKN2A/2B. Emerging evidence support the effectiveness of targeted therapies for brain tumors with BRAF V600E mutation. Here we describe a dramatic radiographical response to combined therapy with BRAF and MEK inhibitors in a patient with epithelioid GBM harboring BRAF V600E mutation, characterized by thick spinal dissemination. From relapsed tumor procured at autopsy, we established a cell line retaining the BRAF V600E mutation, TERT promoter mutation and CDKN2A/2B loss. Intracranial implantation of these cells into mice resulted in tumors closely resembling the original, characterized by epithelioid tumor cells and dissemination, and invasion into the perivascular spaces. We then confirmed the efficacy of treatment with BRAF and MEK inhibitor both in vitro and in vivo. Epithelioid GBM with BRAF V600E mutation can be considered a good treatment indication for precision medicine, and this patient-derived cell line should be useful for prediction of the tumor response and clarification of its biological characteristics.

Evaluation of EZH2 expression, BRAF V600E mutation, and CDKN2A/B deletions in epithelioid glioblastoma and anaplastic pleomorphic xanthoastrocytoma

INTRODUCTION

Epithelioid glioblastoma (EGBM) and anaplastic pleomorphic xanthoastrocytoma (APXA) are two rare entities with different prognoses. However, they share certain morphological and molecular features. MATERIALS AND METHODS: To better recognize EGBM and APXA and identify the prognostic factors associated with these tumors, EZH2 status, BRAF V600E mutations, and CDKN2A/B deletions were assessed in 15 APXA and 13 EGBM cases.

RESULTS

The expression level of EZH2 was found to increase with tumor grade. Overexpression of EZH2 occurred in 69.2% (9/13) of EGBM cases and 20% (3/15) of APXA cases. In addition, 72.7% (8/11) of EGBM and 12.5% (1/8) of APXA cases harbored a CDKN2A homozygous deletion based on fluorescence in situ hybridization. BRAF V600E mutations were detected in 80% (8/10) of EGBM cases and 42.9% (3/7) of APXA cases. Furthermore, EGBM, which exhibited co-existing low-grade glioma-like lesions, was found to have strong EZH2 expression and high Ki-67 indexes only in epithelioid cells and not in low grade lesions. Univariate analysis demonstrated that abundant epithelioid cells, extensive necrosis, EZH2 overexpression and BRAF V600E mutations were significantly associated with decreased overall survival in EGBM and APXA patients (P < 0.05).

CONCLUSIONS

The results suggested that testing for EZH2 expression and BRAF V600E mutations might be helpful to evaluate the prognoses of EGBM and APXA patients. The presence of heterogeneous EZH2 expression in biphasic EGBMs could also contribute to malignant progression.

The Radiological Imaging Features of Easily Misdiagnosed Epithelioid Glioblastoma in Seven Patients

OBJECTIVE

We review the radiological imaging features and report histopathological findings of 7 adult patients with epithelioid glioblastoma (eGBM), which was a newly revised subtype of glioblastoma.

METHODS

Seven adult patients with a diagnosis of eGBM on a brain tissue specimen were retrospectively confirmed by pathology. The tumor magnetic resonance imaging characteristics such as location, number, edema, necrosis, hemorrhage, enhancement, diffusion-weighted image, apparent diffusion coefficient, magnetic resonance spectroscopy, dynamic susceptibility contrast-perfusion-weighted imaging, and histopathological findings were documented.

RESULTS

The tumors of these patients exhibited iso-hyperintensive signal on the T2-weighted image and iso-hypointensive signal on the T1-weighted image. All the lesions manifested iso-hypointensive signal on the diffusion-weighted image, and 2 cases showed significantly restricted hyperintensive signal (2/7). Peritumoral edema in all cases was mild. Five cases were located in the cortical lobe (5/7) and the other 2 were multifocal (2/7). Four cases showed white matter collapse sign (4/7). These tumors revealed apparent enhancement after contrast injection. In particular, 4 cases displayed capsuled sign (4/7), 2 cases showed dura mater tail sign (2/7), and 1 case showed hemorrhage (1/7). The mean value of apparent diffusion coefficient in 6 cases was 1.09 × 10^-3 mm²/s. The mean value of relative cerebral blood volume in 3 cases was 2.84 × 10^-3 mm²/s on dynamic susceptibility contrast-perfusion-weighted imaging. The average value of the choline/N-acetyl aspartate ratio in 4 cases was 6.47 × 10^-3 mm²/s on magnetic resonance spectroscopy. All cases expressed a BRAF V600E mutation according to molecular characteristics.

CONCLUSIONS

eGBMs that were predominantly located in cortex with mild peritumoral edema, white matter collapse, encapsular sign, and dura mater tail sign could be easily misdiagnosed as cortex-involved intracranial brain tumor such as meningioma, whereas multifocal tumors could be easily misdiagnosed as metastatic tumor and lymphoma. Multimodal images were helpful for the differential diagnosis.

The Radiological Imaging Features of Easily Misdiagnosed Epithelioid Glioblastoma in Seven Patients

OBJECTIVE

We review the radiological imaging features and report histopathological findings of 7 adult patients with epithelioid glioblastoma (eGBM), which was a newly revised subtype of glioblastoma.

METHODS

Seven adult patients with a diagnosis of eGBM on a brain tissue specimen were retrospectively confirmed by pathology. The tumor magnetic resonance imaging characteristics such as location, number, edema, necrosis, hemorrhage, enhancement, diffusion-weighted image, apparent diffusion coefficient, magnetic resonance spectroscopy, dynamic susceptibility contrast-perfusion-weighted imaging, and histopathological findings were documented.

RESULTS

The tumors of these patients exhibited iso-hyperintensive signal on the T2-weighted image and iso-hypointensive signal on the T1-weighted image. All the lesions manifested iso-hypointensive signal on the diffusion-weighted image, and 2 cases showed significantly restricted hyperintensive signal (2/7). Peritumoral edema in all cases was mild. Five cases were located in the cortical lobe (5/7) and the other 2 were multifocal (2/7). Four cases showed white matter collapse sign (4/7). These tumors revealed apparent enhancement after contrast injection. In particular, 4 cases displayed capsuled sign (4/7), 2 cases showed dura mater tail sign (2/7), and 1 case showed hemorrhage (1/7). The mean value of apparent diffusion coefficient in 6 cases was 1.09 × 10^-3 mm²/s. The mean value of relative cerebral blood volume in 3 cases was 2.84 × 10^-3 mm²/s on dynamic susceptibility contrast-perfusion-weighted imaging. The average value of the choline/N-acetyl aspartate ratio in 4 cases was 6.47 × 10^-3 mm²/s on magnetic resonance spectroscopy. All cases expressed a BRAF V600E mutation according to molecular characteristics.

CONCLUSIONS

eGBMs that were predominantly located in cortex with mild peritumoral edema, white matter collapse, encapsular sign, and dura mater tail sign could be easily misdiagnosed as cortex-involved intracranial brain tumor such as meningioma, whereas multifocal tumors could be easily misdiagnosed as metastatic tumor and lymphoma. Multimodal images were helpful for the differential diagnosis.

Immunohistochemical and molecular genetic study on epithelioid glioblastoma: Series of seven cases with review of literature

Epithelioid glioblastoma (e-gbm) is a recently described variant of glioblastoma (GBM) which is associated with short survival and now added as a provisional entity to WHO 2016 classification of CNStumors. About half of these tumors show characteristic BRAF-V600E mutation. However, unlike conventional GBMs, e-gbm lack specific diagnostic and prognostic markers. Hence, we aimed to molecularly characterize these tumors. An extensive review of literature was performed.In a multi-institutional effort, all the cases of glioblastoma of year 2017 were reviewed. Cases with predominant epithelioid morphology were analysed. Seven cases of e-gbm (adults:4 and pediatric: 3) were identified. Duration of symptoms varied from 2 weeks to one month. Radiologically, all cases were supratentorial, contrast enhancing with solid and cystic appearance. Majority of the cases were immunopositive for GFAP (71%), EMA (71%), S100 (71%) and vimentin (85%). All the cases showed ATRX, INI-1 and H3K27me3 expression. BRAFV600Emutation was seen in 28% of cases. TERT mutation was seen in 40% cases, while one case showed EGFR amplification. H3F3A mutations and PTEN deletions were seen in none. Although e-gbms are rare, epithelioid morphology of a CNS tumor in a young adult or children with areas of necrosis needs thorough histomorphological and genetic workup.

Intraventricular Epithelioid Glioblastoma: A Case Report

BACKGROUND

Epithelioid glioblastoma, a high-grade, diffuse astrocytic tumor variant, comprises closely packed epithelioid cells and rhabdoid cells. This rare tumor usually develops in the cerebral cortex and diencephalon; however, in the case reported here, it was located intraventricularly.

CASE DESCRIPTION

A 47-year-old woman was referred to our hospital with a right intraventricular mass that had rapidly increased in size. On discovery of the tumor 3 years earlier at the referring hospital, the mass was small, calcified, and attached to the periventricular parenchyma. Over the next 2 years, the mass grew slowly, as observed on periodic magnetic resonance imaging scans. Forty days before the referral, the patient experienced headache and nausea, and marked growth and intratumoral hemorrhage were visible on a computed tomography scan of the head. The tumor was partially removed via a superior parietal lobule corticotomy. Histopathological examination confirmed an isocitrate dehydrogenase-wild-type epithelioid glioblastoma with a BRAF V600E mutation, but the original slow-growing lesion was no longer detected. Consequently, we assume that in this case, a low-grade glioma transformed into an aggressively malignant epithelioid glioblastoma.

CONCLUSIONS

We present the first case of an intraventricular epithelioid glioblastoma that might have arisen from a low-grade glioma with calcification. We recommend including this tumor variant in the differential diagnosis of lateral ventricle tumors.

Glioblastoma in neurofibromatosis 1 patients without IDH1, BRAF V600E, and TERT promoter mutations

Pilocytic astrocytomas and low-grade gliomas are more common compared with glioblastomas in patients with neurofibromatosis 1 (NF1). A recent genome-wide analysis has shown frequent NF1 gene alterations in the mesenchymal subtype of a glioblastoma; however, little is known about clinicopathological features of glioblastomas in NF1 patients (NF1 glioblastomas). We analyzed four NF1 glioblastomas. Radiographical and intraoperative findings showed well-circumscribed tumors from surrounding brain. Pathological analysis presented a paucity of processes with an eosinophilic cytoplasm, bizarre nuclei, xanthomatous-like appearance, multinucleated giant cells, and histiocytoid appearance. During the follow-up period, one patient died at 49 months and others remained alive for 60, 87, and 106 months; thus, patients with NF1 glioblastoma presented a relatively favorable survival. None of the NF1 glioblastomas harbored isocitrate dehydrogenase 1 (IDH1) gene mutation, v-RAF murine sarcoma viral oncogene homolog B1 (BRAF) gene mutation, and telomerase reverse transcriptase (TERT) gene promoter mutation. We identified that NF1 glioblastoma is a unique subset of glioblastoma.

Frequency of BRAF V600E mutations in 969 central nervous system neoplasms

BACKGROUND

Treatment options for oncological diseases have been enhanced by the advent of targeted therapies. The point mutation of the BRAF gene at codon 600 (BRAF V600E) is found in several tumor entities and can be approached with selective inhibitory antibodies. The BRAF inhibitor vemurafenib has demonstrated clinical efficacy in patients with BRAF V600E-mutant melanoma brain metastases and in other cancer diseases. Therefore the BRAF V600E mutation is a highly interesting oncological target in brain tumors.

METHODS

This study assesses the BRAF V600E mutation status in 969 intracranial neoplasms using a tissue microarray method and immunohistochemical staining with the mutation-specific VE-1 antibody, followed by sequencing of positively stained cases.

RESULTS

Out of 784 primary brain tumors seven cases with a BRAF V600E mutation were detected (7/784, 1 %). Six of these cases were neuroepithelial tumors (6/667, 1 %) encompassing 2 astrocytomas WHO grade II (2/42, 5 %), 1 gliosarcoma WHO grade IV (1/75, 1 %) and 3 glioblastomas WHO grade IV (3/312, 1 %). Interestingly, all three mutant glioblastomas showed epithelioid histopathological features. Patients with V600E mutated astrocytic tumors were significantly younger (mean age 15.3 years) than wildtype cases (58.2 years). Among three rhabdoid meningiomas, one case was mutated (1/3) while all other grade I-III meningiomas (1/116, 1 %) and all fifty vestibular schwannomas analyzed were of wildtype status. The vast majority of the BRAF V600E mutations were found in cerebral metastases of malignant melanomas and carcinomas (29/135, 22 %), with false-positive staining found in four breast cancer cases and two non-small-cell lung carcinoma (NSCLC) samples.

CONCLUSIONS

Our data suggest routine screening for BRAF V600E mutations for glioblastomas WHO grade IV below the age of 30, especially in glioblastomas with epithelioid features and in all rhabdoid meningiomas WHO grade III. For colorectal carcinoma, thyroid cancer, malignant melanoma and gliomas BRAF V600E immunostaining is sufficient for screening purposes. We also recommend routine immunohistochemical staining followed by sequencing validation in rare CNS metastases or metastases of unknown primary. Immunohistochemical analysis using mutation-specific antibodies on tissue microarrays is a feasible, time- and cost-efficient approach to high-throughput screening for specific mutations in large tumor series but sequencing validation is necessary in unexpected cases.

A case of osteoclast-like giant cell-rich epithelioid glioblastoma with BRAF V600E mutation

Epithelioid glioblastomas (E-GBMs) are rare, highly aggressive tumors consisting of closely packed tumor cells with smooth, round cell borders and abundant eosinophilic cytoplasm. They tend to affect younger patients compared with conventional GBM. BRAF V600E mutation is characteristically found in approximately 50% of all E-GBMs, compared with a low frequency of this mutation in conventional GBM. Here, we report an unusual case of glioma involving the right frontal lobe, basal ganglia and thalamus in an HIV-positive 30-year-old man on antiretroviral therapy. The lesion was composed of abundant discohesive, monotonous epithelioid cells with extensive necrosis, spindle and polyhedral cells, low-grade oligoastrocytoma-like areas, sarcomatous components, and numerous osteoclast-like giant cells (OLGCs) intermingled with epithelioid tumor cells. As the epithelioid cells accounted for more than one-third of the tumor, a pathological diagnosis of E-GBM was made. BRAF V600E mutation was detected in both oligoastrocytoma-like and epithelioid cell components. Similar to previously reported findings on E-GBM associated with low-grade glioma, this case suggested that low-grade astrocytic glioma with BRAF V600E mutation progressed to E-GBM. OLGCs are rarely observed in gliomas, and this is the first case report of E-GBM associated with abundant OLGC infiltration.