Athymic mice reveal a requirement for T-cell-microglia interactions in establishing a microenvironment supportive of Nf1 low-grade glioma growth.

Pediatric low-grade gliomas (LGGs) frequently do not engraft in immunocompromised mice, limiting their use as an experimental platform. In contrast, murine Neurofibromatosis-1 (Nf1) optic LGG stem cells (o-GSCs) form glioma-like lesions in wild-type, but not athymic, mice following transplantation. Here, we show that the inability of athymic mice to support o-GSC engraftment results from impaired microglia/macrophage function, including reduced expression of Ccr2 and Ccl5, both of which are required for o-GSC engraftment and Nf1 optic glioma growth. Impaired Ccr2 and Ccl5 expression in athymic microglia/macrophages was restored by T-cell exposure, establishing T-cell-microglia/macrophage interactions as critical stromal determinants that support NF1 LGG growth.

Expanded analysis of high-grade astrocytoma with piloid features identifies an epigenetically and clinically distinct subtype associated with neurofibromatosis type 1.

High-grade astrocytoma with piloid features (HGAP) is a recently recognized glioma type whose classification is dependent on its global epigenetic signature. HGAP is characterized by alterations in the mitogen-activated protein kinase (MAPK) pathway, often co-occurring with CDKN2A/B homozygous deletion and/or ATRX mutation. Experience with HGAP is limited and to better understand this tumor type, we evaluated an expanded cohort of patients (n = 144) with these tumors, as defined by DNA methylation array testing, with a subset additionally evaluated by next-generation sequencing (NGS). Among evaluable cases, we confirmed the high prevalence CDKN2A/B homozygous deletion, and/or ATRX mutations/loss in this tumor type, along with a subset showing NF1 alterations. Five of 93 (5.4%) cases sequenced harbored TP53 mutations and RNA fusion analysis identified a single tumor containing an NTRK2 gene fusion, neither of which have been previously reported in HGAP. Clustering analysis revealed the presence of three distinct HGAP subtypes (or groups = g) based on whole-genome DNA methylation patterns, which we provisionally designated as gNF1 (n = 18), g1 (n = 72), and g2 (n = 54) (median ages 43.5 years, 47 years, and 32 years, respectively). Subtype gNF1 is notable for enrichment with patients with Neurofibromatosis Type 1 (33.3%, p = 0.0008), confinement to the posterior fossa, hypermethylation in the NF1 enhancer region, a trend towards decreased progression-free survival (p = 0.0579), RNA processing pathway dysregulation, and elevated non-neoplastic glia and neuron cell content (p < 0.0001 and p < 0.0001, respectively). Overall, our expanded cohort broadens the genetic, epigenetic, and clinical phenotype of HGAP and provides evidence for distinct epigenetic subtypes in this tumor type.

Normalization of electroretinogram and symptom resolution of melanoma-associated retinopathy with negative autoantibodies after treatment with programmed death-1 (PD-1) inhibitors for metastatic melanoma.

Melanoma-associated retinopathy (MAR) is a paraneoplastic syndrome that involves the production of autoantibodies which can cross-react with retinal epitopes leading to visual symptoms. Autoantibodies can target intracellular proteins, and only a few are directed against membrane proteins. This discrepancy in autoantibody-protein target can translate into different immune responses (T-cell mediated vs B-cell mediated). Historically, treatment of MAR has focused on surgical reduction or immunosuppressive medication, mainly glucocorticoids. However, tumor resection is not relevant in metastatic melanoma in which MAR is mostly encountered. Moreover, the use of glucocorticoids can reduce the efficacy of immunotherapy. We report the first case to our knowledge with subjective resolution of visual symptoms and objective evidence of normalization of electroretinogram of MAR with undetectable autoantibodies after administration of programmed death-1 (PD-1) inhibitor (pembrolizumab) without the use of surgical reduction or systemic immunosuppression. This case highlights the potential improvement and resolution of negative autoantibody MAR with the use of PD-1 inhibitors and emphasizes the importance of multidisciplinary approach and team discussion to avoid interventions that can decrease immunotherapy-mediated anti-tumor effect.

Biallelic ASCC1 variants including a novel intronic variant result in expanded phenotypic spectrum of spinal muscular atrophy with congenital bone fractures 2 (SMABF2).

Spinal muscular atrophy with congenital bone fractures 2 (SMABF2), a type of arthrogryposis multiplex congenita (AMC), is characterized by congenital joint contractures, prenatal fractures of long bones, and respiratory distress and results from biallelic variants in ASCC1. Here, we describe an infant with severe, diffuse hypotonia, congenital contractures, and pulmonary hypoplasia characteristic of SMABF2, with the unique features of cleft palate, small spleen, transverse liver, and pulmonary thromboemboli with chondroid appearance. This infant also had impaired coagulation with diffuse petechiae and ecchymoses which has only been reported in one other infant with AMC. Using trio whole genome sequencing, our proband was identified to have biallelic variants in ASCC1. Using deep next generation sequencing of parental cDNA, we characterized alteration of splicing encoded by the novel, maternally inherited ASCC1 variant (c.297-8 T > G) which provides a mechanism for functional pathogenicity. The paternally inherited ASCC1 variant is a rare nonsense variant (c.466C > T; p.Arg156*) that has been previously identified in one other infant with AMC. This report extends the phenotypic characteristics of ASCC1-associated AMC (SMABF2) and describes a novel intronic variant that partially disrupts RNA splicing.

Transcriptional profiling of medulloblastoma with extensive nodularity (MBEN) reveals two clinically relevant tumor subsets with VSNL1 as potent prognostic marker.

Medulloblastoma with extensive nodularity (MBEN) is one of the few central nervous system (CNS) tumor entities occurring in infants which is traditionally associated with good to excellent prognosis. Some MBEN, however, have been reported with an unfavorable clinical course. We performed an integrated DNA/RNA-based molecular analysis of a multi-institutional MBEN cohort (n = 41) to identify molecular events which might be responsible for variability in patients' clinical outcomes. RNA sequencing analysis of this MBEN cohort disclosed two clear transcriptome clusters (TCL) of these CNS tumors: "TCL1 MBEN" and "TCL2 MBEN" which were associated with various gene expression signatures, mutational landscapes and, importantly, prognosis. Thus, the clinically unfavorable "TCL1 MBEN" subset revealed transcriptome signatures composed of cancer-associated signaling pathways and disclosed a high frequency of clinically relevant germline PTCH1/SUFU alterations. In contrast, gene expression profiles of tumors from the clinically favorable "TCL2 MBEN" subgroup were associated with activation of various neurometabolic and neurotransmission signaling pathways, and germline SHH-pathway gene mutations were extremely rare in this transcriptome cluster. "TCL2 MBEN" also revealed strong and ubiquitous expression of VSNL1 (visinin-like protein 1) both at the mRNA and protein level, which was correlated with a favorable clinical course. Thus, combining mutational and epigenetic profiling with transcriptome analysis including VSNL1 immunohistochemistry, MBEN patients could be stratified into clinical risk groups of potential value for subsequent treatment planning.

Successful Use of BRAF/MEK Inhibitors as a Neoadjuvant Approach in the Definitive Treatment of Papillary Craniopharyngioma.

Craniopharyngiomas are rare tumors that arise in the suprasellar region of the brain and are known for their aggressive nature despite their WHO grade I. This is due to the complex neuroanatomy of the sellar/suprasellar region and their proximity to the optic nerve apparatus, hypothalamic-pituitary tract, and other critical neuroanatomical structures. Definitive treatment is based on a multidisciplinary approach and often involves a combination of surgical, radiation, and medical therapy. However, there is high morbidity associated with surgery and RT due to the complex neuroanatomy of this region. Recently, BRAFV600E somatic mutation has been identified in most papillary craniopharyngiomas. This discovery has led to the novel use of RAF pathway inhibitors to treat these tumors. We report the successful use of dabrafenib (BRAF inhibitor) and trametinib (mitogen-activated protein kinase kinase inhibitor) in the neoadjuvant setting followed by definitive stereotactic radiosurgery. We propose an algorithm based on available literature on the integration of targeted therapy in the management of papillary craniopharyngiomas. Our observations, together with prior case reports, advocate the incorporation of targeted therapy for unresectable craniopharyngiomas and reinforce that treatment with dual-targeted therapy is safe and effective.

A multi-institutional analysis of clinical outcomes and patterns of care of 1p/19q codeleted oligodendrogliomas treated with adjuvant or salvage radiation therapy.

PURPOSE: Practice patterns vary for adjuvant treatment of 1p/19q-codeleted oligodendroglioma patients. This study evaluates the outcomes of adjuvant (aRT) versus salvage radiation therapy (sRT) in a multi-institutional cohort. METHODS: Oligodendroglioma patients with confirmed 1p/19q codeletion who were treated with RT with or without chemotherapy from 2000 to 2017 at four tertiary centers were retrospectively reviewed. Overall survival (OS), post-RT progression-free survival (PFS), freedom-from-RT (FFRT), and radiation necrosis (RN) rates were determined using Kaplan-Meier analyses. OS1/PFS1 were defined from the initial surgery. OS2/PFS2 were defined from the RT start-date. Multivariable analyses (MVAs) of prognostic factors for OS and PFS were performed with Cox regression. RESULTS: One hundred eighty-six patients were identified: 124(67%) received aRT and 62(33%) received sRT; of sRT patients, 58% were observed after surgery while 42% received chemotherapy without aRT. The median time from initial diagnosis to sRT was 61 months, and 74% had reoperations before sRT. sRT had longer OS1 than aRT (94% vs. 69% at 10 years, p = 0.03) and PFS1 (10-year PFS of 80% vs. 68%, p = 0.03), though sRT was not associated with significantly different OS1/PFS1 on MVAs. Chemotherapy did not delay sRT compared to observation and had worse PFS2 (42% vs. 79% at 5 years, p = 0.08). Higher RT dose was not associated with improved clinical outcomes but was associated with higher symptomatic RN rate (15% vs. 0% at 2 years, p = 0.003). CONCLUSIONS: Delaying RT for selected oligodendroglioma patients appears safe. Adjuvant chemotherapy does not delay sRT longer than observation and may be associated with worse PFS after RT.

An image processing algorithm to aid diagnosis of mesial temporal sclerosis in children: a case-control study.

BACKGROUND: Mesial temporal sclerosis (MTS) is an important cause of intractable epilepsy. Early and accurate diagnosis of MTS is essential to providing curative and life-changing therapy but can be challenging in children in whom the impact of diagnosis is particularly high. Magnetic resonance imaging (MRI) plays an important role in the diagnosis of MTS, and image processing of MRI is a recently studied strategy to improve its accuracy. OBJECTIVE: In a retrospective case-control study, we assessed the performance of an image processing algorithm (Correlative Image Enhancement [CIE]) for detecting MTS-related hippocampal signal abnormality in children. MATERIALS AND METHODS: Twenty-seven pediatric MTS cases (9 males, 18 females; mean age: 16±standard deviation [SD] 6.7 years) were identified from a pathology database of amygdylo-hippocampectomies performed in children with epilepsy. Twenty-seven children with no seizure history (9 males, 18 females; mean age: 13.8±SD 2.8 years), and with normal brain MRI, were identified for the control group. Blinded investigators processed the MRI coronal FLAIR (fluid-attenuated inversion recovery) images with CIE, saved the processed images as a separate series, and made equivalent region of interest measurements on the processed and unprocessed series to calculate contrast-to-noise ratio. Six blinded reviewers then rated the randomized series for hippocampal signal abnormality and MTS disease status. RESULTS: CIE increased signal intensity and contrast-to-noise ratio in 26/27 hippocampi with pathologically confirmed MTS (96.3%) with the mean (SD) contrast-to-noise ratio of cases increasing from 14.9 (11.1) to 77.7 (58.7) after processing (P<0.001). Contrast-to-noise ratio increased in 1/54 normal control hippocampi (1.9%), with no significant change in the mean contrast-to-noise ratio of the control group after processing (P=0.57). Mean (SD) reader sensitivity for detecting abnormal signal intensity increased from 83.3% (14.2) to 94.8% (3.3) after processing. Mean specificity for abnormal signal intensity increased from 94.4% (7.3) to 96.3% (0). While sensitivity improved after processing for detection of MTS disease status in 4/6 readers, the mean reader sensitivity and specificity for MTS detection increased only minimally after processing, from 79.6% to 80.7% and from 95.7% to 96.3%, respectively. CONCLUSION: The CIE image processing algorithm selectively increased the contrast-to-noise ratio of hippocampi affected by MTS, improved reader performance in detecting MTS-related hippocampal signal abnormality and could have high impact on pediatric patients undergoing work-up for seizures.

Pediatric glioma-associated KIAA1549:BRAF expression regulates neuroglial cell growth in a cell type-specific and mTOR-dependent manner.

Tandem duplications involving the BRAF kinase gene have recently been identified as the most frequent genetic alteration in sporadic pediatric glioma, creating a novel fusion protein (f-BRAF) with increased BRAF activity. To define the role of f-BRAF in gliomagenesis, we demonstrate that f-BRAF regulates neural stem cell (NSC), but not astrocyte, proliferation and is sufficient to induce glioma-like lesions in mice. Moreover, f-BRAF-driven NSC proliferation results from tuberin/Rheb-mediated mammalian target of rapamycin (mTOR) hyperactivation, leading to S6-kinase-dependent degradation of p27. Collectively, these results establish mTOR pathway activation as a key growth regulatory mechanism common to both sporadic and familial low-grade gliomas in children.

Acute Posterior Multifocal Placoid Pigment Epitheliopathy Complicated by Fatal Cerebral Vasculitis.

A 21-year-old man experienced unilateral vision loss associated with multiple atrophic chorioretinal lesions. He was treated for a presumptive diagnosis of acute retinal necrosis, but his vision did not improve with antiviral therapy. Over the course of several weeks, his symptoms progressed to involve both eyes. The fellow eye showed characteristic yellow-white placoid lesions, prompting treatment with oral corticosteroids for acute posterior multifocal placoid pigment epitheliopathy (APMPPE). Despite high-dose therapy with prednisone 80 mg daily, the patient developed the acute onset of mental status changes within the next several days. Neuroimaging revealed multifocal large-vessel strokes associated with cerebral edema; these infarcts led to herniation and death. Postmortem histopathologic examination confirmed granulomatous inflammation in both ocular and cerebral vasculatures. Together with findings from multimodal imaging obtained throughout this patient's clinical course, our findings support the notion that granulomatous choroiditis is the mechanism of the ocular lesions seen in APMPPE. This granulomatous inflammation can also affect cerebral vessels, leading to strokes.

An NAD+-dependent transcriptional program governs self-renewal and radiation resistance in glioblastoma.

Accumulating evidence suggests cancer cells exhibit a dependency on metabolic pathways regulated by nicotinamide adenine dinucleotide (NAD+). Nevertheless, how the regulation of this metabolic cofactor interfaces with signal transduction networks remains poorly understood in glioblastoma. Here, we report nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting step in NAD+ synthesis, is highly expressed in glioblastoma tumors and patient-derived glioblastoma stem-like cells (GSCs). High NAMPT expression in tumors correlates with decreased patient survival. Pharmacological and genetic inhibition of NAMPT decreased NAD+ levels and GSC self-renewal capacity, and NAMPT knockdown inhibited the in vivo tumorigenicity of GSCs. Regulatory network analysis of RNA sequencing data using GSCs treated with NAMPT inhibitor identified transcription factor E2F2 as the center of a transcriptional hub in the NAD+-dependent network. Accordingly, we demonstrate E2F2 is required for GSC self-renewal. Downstream, E2F2 drives the transcription of members of the inhibitor of differentiation (ID) helix-loop-helix gene family. Finally, we find NAMPT mediates GSC radiation resistance. The identification of a NAMPT-E2F2-ID axis establishes a link between NAD+ metabolism and a self-renewal transcriptional program in glioblastoma, with therapeutic implications for this formidable cancer.

Rapid Clinical and Radiographic Response With Combined Dabrafenib and Trametinib in Adults With BRAF-Mutated High-Grade Glioma.

BRAF V600E mutations have been successfully treated with targeted therapy in melanoma, non-small cell lung cancer, and thyroid cancer. Interestingly, these mutations have also been identified in a subset of pediatric and adult brain tumors, with several cases reportedly responding to targeted therapy. However, these reports have been limited to single-agent BRAF inhibitor therapy and recurrent disease. Herein, we report dramatic clinical and radiographic responses to combination dabrafenib (BRAF inhibitor) and trametinib (MEK inhibitor) in 2 adults with high-grade gliomas (HGGs), with 1 patient treated in the first-line setting. These observations, together with prior case reports, advocate for routine screening of BRAF point mutations in adult HGGs, and suggest that treatment with dual-targeted therapy, even in newly diagnosed cases, is safe and effective.

Analysis of point mutations and copy number variation in Grade II and III meningioma.

Meningiomas are among the most common tumors of the adult central nervous system (CNS). They are classified by the World Health Organization into three pathologic grades with increasing severity: grade I are benign with favorable treatment outcomes and low recurrence rates while grade III display malignant behavior and poor progression-free survival. Previous studies have shown that inactivation of NF-2 is the most common genetic event in high-grade meningioma; however, there is dearth of molecular data to distinguish grade II (AM-II) from the even more aggressive grade III (AM-III). As part of a routine diagnostic workup, 19 AM-II and 5 AM-III were submitted for targeted sequencing on a panel of twenty-four genes relevant to CNS tumors. The data generated during the course of clinical care was collected and re-analyzed with the aim of identifying molecular features to distinguish AM-II and AM-III. Our cases contained several well-characterized, potentially actionable mutations, but we did not find any novel, recurrent sequence variants. Copy number variations were common in both AM-II and AM-III; chr22q loss was the most prevalent followed in decreasing frequency by losses of chr1p, chr14q, and chr10. In particular, chr10 loss was noted in 4 of 5 AM-III cases but none of the AM-II cases. This suggests that chr10 loss may serve as a diagnostic and perhaps a prognostic marker to differentiate AM-II from AM-III. If confirmed in larger studies, our finding could further aid the classification of meningioma.

Clinical genomic profiling identifies TYK2 mutation and overexpression in patients with neurofibromatosis type 1-associated malignant peripheral nerve sheath tumors.

BACKGROUND: Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive sarcomas that arise at an estimated frequency of 8% to 13% in individuals with neurofibromatosis type 1 (NF1). Compared with their sporadic counterparts, NF1-associated MPNSTs (NF1-MPNSTs) develop in young adults, frequently recur (approximately 50% of cases), and carry a dismal prognosis. As such, most individuals affected with NF1-MPNSTs die within 5 years of diagnosis, despite surgical resection combined with radiotherapy and chemotherapy. METHODS: Clinical genomic profiling was performed using 1000 ng of DNA from 7 cases of NF1-MPNST, and bioinformatic analyses were conducted to identify genes with actionable mutations. RESULTS: A total of 3 women and 4 men with NF1-MPNST were identified (median age, 38 years). Nonsynonymous mutations were discovered in 4 genes (neurofibromatosis type 1 [NF1], ROS proto-oncogene 1 [ROS1], tumor protein p53 [TP53], and tyrosine kinase 2 [TYK2]), which in addition were mutated in other MPNST cases in this sample set. Consistent with their occurrence in individuals with NF1, all tumors had at least 1 mutation in the NF1 gene. Whereas TP53 gene mutations are frequently observed in other cancers, ROS1 mutations are common in melanoma (15%-35%), another neural crest-derived malignancy. In contrast, TYK2 mutations are uncommon in other malignancies (<7%). In the current series, recurrent TYK2 mutations were identified in 2 cases of NF1-MPNST (30% of cases), whereas TYK2 protein overexpression was observed in 60% of MPNST cases using an independently generated tissue microarray, regardless of NF1 status. CONCLUSIONS: Clinical genomic analysis of the current series of NF1-MPNST cases found that TYK2 is a new gene mutated in MPNST. Future work will focus on examining the utility of TYK2 expression as a biomarker and therapeutic target for these cancers. Cancer 2017;123:1194-1201. © 2016 American Cancer Society.

Comprehensive Genomic Profiling of 282 Pediatric Low- and High-Grade Gliomas Reveals Genomic Drivers, Tumor Mutational Burden, and Hypermutation Signatures.

BACKGROUND: Pediatric brain tumors are the leading cause of death for children with cancer in the U.S. Incorporating next-generation sequencing data for both pediatric low-grade (pLGGs) and high-grade gliomas (pHGGs) can inform diagnostic, prognostic, and therapeutic decision-making. MATERIALS AND METHODS: We performed comprehensive genomic profiling on 282 pediatric gliomas (157 pHGGs, 125 pLGGs), sequencing 315 cancer-related genes and calculating the tumor mutational burden (TMB; mutations per megabase [Mb]). RESULTS: In pLGGs, we detected genomic alterations (GA) in 95.2% (119/125) of tumors. BRAF was most frequently altered (48%; 60/125), and FGFR1 missense (17.6%; 22/125), NF1 loss of function (8.8%; 11/125), and TP53 (5.6%; 7/125) mutations were also detected. Rearrangements were identified in 35% of pLGGs, including KIAA1549-BRAF, QKI-RAF1, FGFR3-TACC3, CEP85L-ROS1, and GOPC-ROS1 fusions. Among pHGGs, GA were identified in 96.8% (152/157). The genes most frequently mutated were TP53 (49%; 77/157), H3F3A (37.6%; 59/157), ATRX (24.2%; 38/157), NF1 (22.2%; 35/157), and PDGFRA (21.7%; 34/157). Interestingly, most H3F3A mutations (81.4%; 35/43) were the variant K28M. Midline tumor analysis revealed H3F3A mutations (40%; 40/100) consisted solely of the K28M variant. Pediatric high-grade gliomas harbored oncogenic EML4-ALK, DGKB-ETV1, ATG7-RAF1, and EWSR1-PATZ1 fusions. Six percent (9/157) of pHGGs were hypermutated (TMB >20 mutations per Mb; range 43-581 mutations per Mb), harboring mutations deleterious for DNA repair in MSH6, MSH2, MLH1, PMS2, POLE, and POLD1 genes (78% of cases). CONCLUSION: Comprehensive genomic profiling of pediatric gliomas provides objective data that promote diagnostic accuracy and enhance clinical decision-making. Additionally, TMB could be a biomarker to identify pediatric glioblastoma (GBM) patients who may benefit from immunotherapy. IMPLICATIONS FOR PRACTICE: By providing objective data to support diagnostic, prognostic, and therapeutic decision-making, comprehensive genomic profiling is necessary for advancing care for pediatric neuro-oncology patients. This article presents the largest cohort of pediatric low- and high-grade gliomas profiled by next-generation sequencing. Reportable alterations were detected in 95% of patients, including diagnostically relevant lesions as well as novel oncogenic fusions and mutations. Additionally, tumor mutational burden (TMB) is reported, which identifies a subpopulation of hypermutated glioblastomas that harbor deleterious mutations in DNA repair genes. This provides support for TMB as a potential biomarker to identify patients who may preferentially benefit from immune checkpoint inhibitors.

Genetic alterations in uncommon low-grade neuroepithelial tumors: BRAF, FGFR1, and MYB mutations occur at high frequency and align with morphology.

Low-grade neuroepithelial tumors (LGNTs) are diverse CNS tumors presenting in children and young adults, often with a history of epilepsy. While the genetic profiles of common LGNTs, such as the pilocytic astrocytoma and 'adult-type' diffuse gliomas, are largely established, those of uncommon LGNTs remain to be defined. In this study, we have used massively parallel sequencing and various targeted molecular genetic approaches to study alterations in 91 LGNTs, mostly from children but including young adult patients. These tumors comprise dysembryoplastic neuroepithelial tumors (DNETs; n = 22), diffuse oligodendroglial tumors (d-OTs; n = 20), diffuse astrocytomas (DAs; n = 17), angiocentric gliomas (n = 15), and gangliogliomas (n = 17). Most LGNTs (84 %) analyzed by whole-genome sequencing (WGS) were characterized by a single driver genetic alteration. Alterations of FGFR1 occurred frequently in LGNTs composed of oligodendrocyte-like cells, being present in 82 % of DNETs and 40 % of d-OTs. In contrast, a MYB-QKI fusion characterized almost all angiocentric gliomas (87 %), and MYB fusion genes were the most common genetic alteration in DAs (41 %). A BRAF:p.V600E mutation was present in 35 % of gangliogliomas and 18 % of DAs. Pathogenic alterations in FGFR1/2/3, BRAF, or MYB/MYBL1 occurred in 78 % of the series. Adult-type d-OTs with an IDH1/2 mutation occurred in four adolescents, the youngest aged 15 years at biopsy. Despite a detailed analysis, novel genetic alterations were limited to two fusion genes, EWSR1-PATZ1 and SLMAP-NTRK2, both in gangliogliomas. Alterations in BRAF, FGFR1, or MYB account for most pathogenic alterations in LGNTs, including pilocytic astrocytomas, and alignment of these genetic alterations and cytologic features across LGNTs has diagnostic implications. Additionally, therapeutic options based upon targeting the effects of these alterations are already in clinical trials.

Molecular and histologic characteristics of pseudoprogression in diffuse gliomas.

During the 6 month period following chemoradiotherapy, gliomas frequently develop new areas of contrast enhancement, which are due to treatment effect rather than tumor progression. We sought to characterize this phenomenon in oligodendrogliomas (OG) and mixed oligoastrocytomas (MOA). We reviewed the imaging findings from 143 patients with a WHO grade II or III OG or MOA for evidence of pseudoprogression (PsP) or early tumor progression. We characterized these cases for 1p/19q codeletions by FISH, IDH1 R132H mutation by immunohistochemistry, and TP53, ATRX, and EGFR mutations by next generation sequencing. We then reviewed the pathologic specimens of the patient cases in which a re-resection was performed. We found that OG and MOA that are 1p/19q intact developed PsP at a higher rate than tumors that are 1p/19q codeleted (27 vs. 8 %). Moreover, IDH1 wild-type (WT) tumors developed PsP at a higher rate than IDH1 R132H cases (27 vs. 11 %). Patients with ATRX or TP53 mutations developed PsP at an intermediate rate of 21 %. Ten patients in our cohort underwent a re-resection for early contrast enhancement; these tumors were predominantly 1p/19q intact (90 %) and had a low rate of IDH1 R132H mutation (50 %). 8 of 10 tumors demonstrated primarily treatment effects, while the remaining 2 of 10 demonstrated recurrent/residual tumor of the same grade. Early contrast enhancement that develops during the first 6 months after chemoradiotherapy is typically due to PsP and occurs primarily in OG and MOA that are 1p/19q intact and IDH WT.

Central nervous system involvement by myeloid sarcoma: a report of 12 cases and review of the literature.

Myeloid sarcoma (MS) is an extramedullary malignancy of myeloid origin. It can occur in any organ. Common sites are skin, bone, lymph nodes, and soft tissue. Central nervous system (CNS) involvement is very uncommon. We report 12 new pathology-confirmed cases of CNS MS with literature review. Median age was 42.5 years (range: 0 - 84 years). Bone marrow involvement by hematologic neoplasia was co-incidental (n = 8) or occurred 8 - 51 months prior to CNS MS (n = 3). Abnormal radiological findings detected in all patients, included hemorrhagic (n = 5) or enhancing (n = 2) lesions, with multiple ring-enhancing dura-based masses in 1 patient. Seven tumors had abnormal cytogenetics including: t(11; 19) (q23; p13.3), +8, inv (16), t(9; 22), t(8; 21), del(5q), and +21. One had a complex karyotype and 2 were cytogenetically normal. One MS had the JAK2V617F mutation. Treatment modalities included surgery for decompression (n = 2), radiotherapy (n = 2), chemotherapy (n = 6), and stem cell transplant (n = 2). Nine patients died days to 12 months post CNS MS diagnosis (median = 4 months). Two patients were alive without evidence of disease at 16 and 50 months following MS diagnosis and one was lost to follow-up. The clinical and imaging features for CMS MS overlap with those of intracranial hemorrhage and primary CNS tumors. It is therefore important to maintain a high index of suspicion and perform a biopsy whenever clinically appropriate. A meticulous workup is necessary to avoid misdiagnosis of other hematopoietic or nonhematopoietic neoplasms. Since CNS MS is potentially curable, timely recognition is paramount.

Gliosarcomas lack BRAFV600E mutation, but a subset exhibit ß-catenin nuclear localization.

Gliosarcoma (GS) is a rare subtype of glioblastoma (GBM) characterized by both glial and mesenchymal components. Unlike GBM, there are no specific prognostic markers, and optimized treatments for patients with GS do not exist. Recent reports describe BRAFV600E mutation in malignant peripheral nerve sheath tumors, and aberrant Wnt signaling and CTNNB1 (ß-catenin gene) mutations have been described in GBM. We sought to determine whether GS tumors harbor BRAFV600E mutations or aberrant Wnt signaling, as indicated by nuclear localization of ß-catenin, by immunohistochemical detection. Forty-eight (48) cases of primary and secondary adult GS (including recurrent ones) were evaluated by immunohistochemical techniques for the presence of nuclear ß-catenin and the BRAFV600E mutation. A small subset (6/46, 13%) showed nuclear localization of ß-catenin. None of the cases harbored BRAFV600E mutations (0/48). These results are the first to describe the presence of Wnt signaling pathway abnormalities, manifested by nuclear ß-catenin, in a subset, as well as the lack of BRAFV600E mutation in GS. We propose a potential role for Wnt pathway alterations in the pathogenesis of a subset of GS.