Analysis of PD‐L1 expression and T cell infiltration in different molecular subgroups of diffuse midline gliomas

Diffuse midline gliomas (DMGs) are rare and devastating tumors with limited therapeutic options. Programmed death‐ligand 1 (PD‐L1) expression represents a potential predictive biomarker for immunotherapy. One hundred and twenty‐six DMGs (89 adult and 37 pediatric) were assessed for immune profile (PD‐L1, cluster of differentiation (CD3, CD8) and genetic markers (mutation in 27th amino acid of histone H3 (H3K27M), alpha thalassemia/mental retardation syndrome X‐linked (ATRX), isocitrate dehydrogenase 1 (IDH1), p53) by immunohistochemistry. Sanger sequencing was done for IDH1 and H3K27M. The thalamus was the commonest site. Four molecular subgroups of DMGs were identified. H3K27M mutation was more frequent in children (P = 0.0001). The difference in median overall survival (OS) was not significant in any of the four molecular subgroups (P > 0.05). PD‐L1 expression was significantly higher in H3K27M/IDH1 double‐negative adult glioblastomas (GBMs) (P = 0.002). Strong PD‐L1 expression was more frequent in grade IV tumors and thalamic location, although the difference was not significant (P = 0.14 and P = 0.19 respectively). Positive PD‐L1 expression was significantly associated with high tumor‐infiltrating lymphocytes count (P < 0.05). There was no significant difference in median OS in PD‐L1‐positive versus negative cases among four genetic subgroups (P > 0.05). On univariate analysis, there was no direct correlation of PD‐L1 with any genetic alteration, except H3K27M mutation (P = 0.01). CD3 infiltration was similar in both adults and pediatric ages (84.3% and 78.4%, respectively) while CD8 expression was significantly greater in adults compared to children (74.1% vs 37.8%, P = 0.0001). This is the first comprehensive analysis highlighting molecular and immune profiles of DMGs. Despite molecular and clinicopathological diversity, overall survival in DMGs remains dismal. Multicentric studies with larger numbers of cases should be undertaken for stratifying DMGs according to their age, immune and molecular profiles, to develop effective immunotherapies.     

Glioneuronal tumor with neuropil‐like islands: A new entity

Glioneuronal tumor with neuropil‐like islands (GTNI) is a distinctive and rare tumor characterized by both glial and neuronal differentiation. However, unlike other mixed glioneuronal tumors, which are characterized by a favorable prognosis, this neoplasm has been found to be potentially aggressive. We report here a case arising in a 60‐year old male patient who presented with seizures, forgetfulness and right‐sided hemiparesis, due to a left frontal lobe tumor. Unlike most cases described in the literature, the present tumor was unique in its radiological appearance, which was cystic. On microscopic evaluation, the glial component was chiefly gemistocytic punctuated by neuropil‐like islands. Strong nuclear immunolabeling of p53 and absence of 1p/19q deletion by fluorescence in situ hybridization assay were consistent with those in previous reports.     

Cytogenetic study of glioneuronal tumor with neuropil‐like islands: A case report

Glioneuronal tumor with neuropil‐like islands (GTNI) is a recently recognized glioneuronal neoplasm but it was classified as an astrocytic tumor by the World Health Organization (WHO) in 2007. We performed a cytogenetic study in a case of GTNI arising in a 55‐year‐old man and analyzed its genetic alteration. It presented as a heterogeneously enhancing, multi‐lobulating solid mass on MRI. Histopathologically, the tumor showed the biphasic feature of the predominating micronodular neuropil‐like islands and the diffusely infiltrating glial component. In addition, the prominent blood vessels with perivascular hyalinization were observed. On cytogenetic study, loss of 4q, 5q, 11p and gain of 6p, 7, 8, 11q, 12p, 15q were found. The remaining tumor after subtotal resection progressed 7 months later, despite combined chemo‐ and radiotherapy. From the results, it seems that GTNI does not share pathologic or genetic features with conventional astrocytoma, suggesting a unique entity with aggressive behavior.     

Molecular and clinical characterization of H3 K27M-mutant “non-midline” glioblastoma: A case report and literature review

The WHO classification of tumors of the CNS in 2016 defined “diffuse midline glioma, H3 K27M-mutant” as a new tumor entity locating in the CNS midline. However, the H3 K27M-mutation in “non-midline” glioblastoma are rare and their characteristics have been rarely reported. A 16-year-old girl presented a hyper-intense lesion at her left temporal stem on T2WI, FLAIR and DWI. Biopsy was performed and molecular pathological diagnosis was glioblastoma with H3 K27M-mutant. Accordingly, the possibility of H3 K27M-mutant should be examined not only for diffuse glioma without IDH mutation that develops at a midline location, but also in non-midline locations.     

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.     

Pediatric ganglioglioma with an H3 K27M mutation arising from the cervical spinal cord

The 2016 edition of the World Health Organization Classification of Tumors of the Central Nervous System introduced “diffuse midline glioma H3 K27M mutant” as a new diagnostic entity. These tumors predominately affect pediatric patients and arise from midline structures such as the brainstem, thalamus and spinal cord. Here, we report a rare patient with spinal ganglioglioma carrying an H3 K27M mutation. A 10‐year‐old boy presented with an intramedullary tumor in the cervical spinal cord. The lesion was partially removed and histologically diagnosed as ganglioglioma. After the remnant tumor grew within 3 months after surgery, the patient underwent radiotherapy. Genetic analyses revealed an H3F3A K27M mutation but no other genetic alterations such as IDH and BRAF mutations. This case may point to pathological heterogeneity in gliomas with H3 K27M mutations.     

Astroblastoma with unusual signet‐ring‐like cell components: A case report and literature review

We report a case of astroblastoma with unusual signet‐ring‐like cell components. A 33‐year‐old‐woman presented with occasional partial seizures of the face. Radiological studies revealed an enhanced frontal mass lesion. At surgery, a gray, soft, well‐circumscribed mass was seen and shelled out. Histologically, the tumor showed a perivascular arrangement and papillary‐like patterns with compact cellularity. The tumor cells radiating from the hyalinized vessels showed broader, shorter, less tapered processes. A part of each tumor cell displayed prominent islands of signet‐ring‐like cells. Glial fibrillary acidic protein reaction revealed strongly positive staining of tumor cells and signet‐ring‐like cells. Eight years after the operation the patient remains well with no tumor recurrence. It remains to be determined whether, in this astroblastoma, the unusual signet‐ring‐like cell components were related to benign biological characteristics or to the tumor's low‐grade form with incidental signet‐ring‐like cell appearance.     

Loss of NECL1, a novel tumor suppressor,can be restored in glioma by HDAC inhibitor‐Trichostatin A through Sp1 binding site

Nectin‐like molecule 1 (NECL1)/CADM3/IGSF4B/TSLL1/SynCAM3 is a neural tissue‐specific immunoglobulin‐like cell–cell adhesion molecule downregulated at the mRNA level in 12 human glioma cell lines. Here we found that the expression of NECL1 was lost in six glioma cell lines and 15 primary glioma tissues at both RNA and protein levels. Re‐expression of NECL1 into glioma cell line U251 would repress cell proliferation in vitro by inducing cell cycle arrest. And also NECL1 could decrease the growth rate of tumors in nude mice in vivo. To further investigate the mechanism why NECL1 was silenced in glioma, the basic promoter region located at ?271 to +81 in NECL1 genomic sequence was determined. DNA bisulfite sequencing was performed to study the methylation status of CpG islands in NECL1 promoter; however, no hypermethylated CpG site was found. Additionally, the activity of histone deacetylase (HDACs) in glioma was higher than that in normal brain tissues, and the expression of NECL1 in glioma cell lines could be reactivated by HDACs inhibitor‐Trichostatin A (TSA). So the loss of NECL1 in glioma was at least partly caused by histone deacetylation. Luciferase reporter assays, chromatin immunoprecipitation and co‐immunoprecipitation (co‐IP) assays indicated that Sp1 played an important role in this process by binding to either HDAC1 in untreated glioma cells or p300/CBP in TSA treated cells. Our finding suggests that NECL1 may act as a tumor suppressor in glioma and loss of it in glioma may be caused by histone deacetylation. © 2008 Wiley‐Liss, Inc.     

Pathologic diversity of glioneuronal tumor with neuropil-like islands: a histological and immunohistochemical study with a special reference to isocitrate dehydrogenase 1 (IDH1) in 5 cases

Glioneuronal tumor with neuropil-like islands (GTNI) is featured by "neuropil-like islands (NIs)" within dominating astroglial components. Isocitrate dehydrogenase (IDH) mutations, particularly IDH1 R132H (G395A), are found in WHO Grade II and III diffuse gliomas as well as secondary, but not primary, glioblastomas. We reviewed 5 cases of GTNI, and assessed histology and immunohistochemistry with various antibodies, including those for IDH1 R132H, as well as direct DNA sequencing for IDH1 G395A. NIs were variable in morphology, and constantly synaptophysin-positive and glial fibrillary acidic protein-negative. The glioma components were primary glioblastoma in 2 cases, anaplastic astrocytoma in 1 and anaplastic oligoastrocytoma in 2. The IDH1 R132H was expressed in the 2 cases with oligoastrocytoma: In 1, NIs and the astrocytoma-like area as well as the oligodendroglioma-like area were positive. In the other, only the oligodendrogliomalike area was positive. The mutation analysis performed on the latter case with DNA separately sampled from the oligodendroglioma- like area and the astrocytoma-like area detected IDH1 G395A in both areas. We have shown diverse pathologic aspects of GTNI. Also, we have shown that the expression of IDH1 R132H in GTNI is largely concordant with that in diffuse gliomas, and that it can be dependent on each histologic component although the mutant IDH1 gene is ubiquitously present within the tumor.     

Case series of diffuse extraneural metastasis in H3F3A mutant high-grade gliomas: Clinical,molecular phenotype and literature review

H3K27M and H3.3G34R/V mutations have been identified in pediatric high-grade gliomas (pHGG), though extraneural metastases are rarely reported and poorly characterized. Three pHGG patients from two institutions were identified with extraneural metastasis, harboring histone mutations. Their clinical, imaging and molecular characteristics are reported here. A 17-year old female presented with supratentorial H3.3G34R-mutant glioma with metastatic osseous lesions in the spine, pelvis, bone marrow, pleural effusion and soft tissue of pelvis. Bone marrow biopsy and soft tissue of pelvis biopsy showed neoplastic cells positive for P53. A 20-year old female was diagnosed with H3F3A H3K27M–mutant thalamic glioma. She developed diffuse sclerotic osseous lesions. Biopsy of an osseous lesion was non-diagnostic. A 17-year old female presented with a H3F3A H3K27M-mutant diffuse midline glioma with diffuse spinal cord metastasis. She further developed multifocal chest lymphadenopathy, pleural effusions, and a soft tissue mass in the abdominal wall. The latter was positive for H3K27M mutation. We present the first case series of pHGG with H3F3A mutation and diffuse extraneural dissemination, describing their clinical and molecular profile.     

H3K27M-mutant diffuse midline glioma presenting as synchronous lesions involving pineal and suprasellar region: A case report and literature review

IntroductionThe differential diagnoses for multifocal lesions with pineal and suprasellar involvement in a young adult include germ cell tumour and intracranial metastasis. Other differentials include atypical teratoid/rhabdoid tumour and pineoblastoma. We present the first known case of multicentric H3K27M mutant diffuse midline glioma, which is typically defined by its diffuse nature, midline location, and H3K27M mutation.Case reportA young Chinese female presented subacutely with giddiness, right abducens nerve palsy and unsteady gait. Magnetic resonance imaging (MRI) of the brain with contrast revealed a moderately sized pineal region tumour, extending into the third ventricle, associated with hydrocephalus. There were two other synchronous lesions noted in the suprasellar and left occipital region. Serum and cerebrospinal fluid tumour markers, along with a computed tomography scan of her thorax and abdomen and were unremarkable. She underwent an endoscopic third ventriculostomy and biopsy of pineal and suprasellar lesions. Histology demonstrated a poor prognosis variant multifocal glioblastoma multiforme that was IDH wildtype, H3K27M positive, and MGMT unmethylated. MRI of the whole spine did not reveal any drop metastasis. The patient subsequently underwent adjuvant chemotherapy and radiotherapy after she was deemed to be unsuitable for surgical resection.ConclusionAlthough rare, multicentric H3K27M mutant diffuse midline glioma should be included in the list of differential diagnoses for multifocal enhancing lesions with involvement of the pineal and suprasellar regions, especially if the lesions demonstrate imaging features atypical for more common diagnosis such as germ cell tumours.     

High prevalence of developmental venous anomaly in adult patients with midline thalamic diffuse gliomas

ObjectiveThis study aimed to assess the prevalence of developmental venous anomaly (DVA) in patients with thalamic glioma. Furthermore, we explored the association between DVA and some important biomarkers, such as IDH1 mutation, and H3K27M mutation.Patients and MethodsPatients who received tumor resection in West China Hospital between August 2009 and October 2017 were enrolled. Propensity score matching was conducted based on a logistic regression model and 1:1 matching for case and control was used to generate a new cohort from patients with meningioma. Chi-square test, t-test, univariate and multivariate analyses were employed to assess the prevalence of DVA in thalamic glioma and meningioma and to identify risk factors associated with DVA.ResultsNinety-nine patients with thalamic glioma were enrolled in the current study (male, n = 54; female, n = 45). The mean age was 42.9 ± 15.3 years old. We identified a higher prevalence of DVA in 99 patients with thalamic glioma when compared with 99 patients with meningioma (18.18% vs. 7.07%), which was slightly lower than the prevalence of DVA in glioma reported in previous studies. Furthermore, the distribution of gender, age, and tumor grade in DVA did not reach statistical significance. Chi-square test, univariate and multivariate analyses showed that IDH1 mutation, ATRX mutation, MGMT promoter methylation, p53 mutation, MMP9, EGFR, and Top II positive expression, TERT mutation, and H3K27M mutation were not associated with the development of DVA in thalamic glioma.ConclusionA higher prevalence of DVA was found in thalamic glioma compared with meningioma.     

H3K27M mutation in adult cerebellar glioblastoma

A methionine substitution of lysine at residue 27 of histone H3 (H3K27M) mutation has become synonymous with malignant pediatric diffuse midline glioma (DMG), that occurs commonly in the brainstem. Therefore, recent reports that this same mutation occurs in malignant adult glioblastoma (GBM) located in the cerebellum are both unexpected and intriguing. The biological and clinical considerations of this novel finding are discussed.     

不同病理类型和级别胶质瘤细胞IDH1基因突变情况分析

目的探讨国人不同病理类型和级别胶质瘤细胞中异柠檬酸脱氢酶1（IDH1）基因突变情况及其临床意义。方法应用mIDH1 R132H免疫组化学法检测87例国人不同病理类型和级别的胶质瘤标本中IDH1基因突变发生率,分析不同病理类型、不同WHO级别和不同年龄的IDH1基因突变情况。结果 87例国人胶质瘤标本中有45例（51.7%）检出IDH1基因突变,并与胶质瘤的病理类型、WHO分级以及年龄等具有相关性。结论 IDH1基因突变在WHOⅡ、Ⅲ级胶质瘤中的发生率较高,并在胶质瘤的发生、发展过程中起重要作用。     

A case of diffuse midline glioma,H3 K27M mutant mimicking a hemispheric malignant glioma in an elderly patient

Diffuse midline glioma, H3 K27M mutant arises from midline structures of the central nervous system and predominately affects pediatric patients. However, this disease entity was only recently established, and the clinical phenotypic spectrum remains largely unclear. We herein report a rare case of diffuse midline glioma, H3 K27M mutant with an unusual distribution in an elderly woman who presented with a diffuse glioma that invaded both sides of the thalami, and left hippocampus and frontoparietal lobes, thus mimicking a hemispheric malignant glioma. A biopsy of the lobular lesion led to a molecular diagnostic confirmation of diffuse midline glioma, H3 K27M mutant. The patient received concurrent bevacizumab and temozolomide therapy with radiation therapy and survived for 30 months. This case highlights the possibility that a glioma with cerebral hemispheric spread in an elderly patient may harbor the H3 K27M mutation.     

Specific detection of methionine 27 mutation in histone 3 variants (H3K27M) in fixed tissue from high-grade astrocytomas

Studies in pediatric high-grade astrocytomas (HGA) by our group and others have uncovered recurrent somatic mutations affecting highly conserved residues in histone 3 (H3) variants. One of these mutations leads to analogous p.Lys27Met (K27M) mutations in both H3.3 and H3.1 variants, is associated with rapid fatal outcome, and occurs specifically in HGA of the midline in children and young adults. This includes diffuse intrinsic pontine gliomas (80 %) and thalamic or spinal HGA (>90 %), which are surgically challenging locations with often limited tumor material available and critical need for specific histopathological markers. Here, we analyzed formalin-fixed paraffin-embedded tissues from 143 pediatric HGA and 297 other primary brain tumors or normal brain. Immunohistochemical staining for H3K27M was compared to tumor genotype, and also compared to H3 tri-methylated lysine 27 (H3K27me3) staining, previously shown to be drastically decreased in samples carrying this mutation. There was a 100 % concordance between genotype and immunohistochemical analysis of H3K27M in tumor samples. Mutant H3K27M was expressed in the majority of tumor cells, indicating limited intra-tumor heterogeneity for this specific mutation within the limits of our dataset. Both H3.1 and H3.3K27M mutants were recognized by this antibody while non-neoplastic elements, such as endothelial and vascular smooth muscle cells or lymphocytes, did not stain. H3K27me3 immunoreactivity was largely mutually exclusive with H3K27M positivity. These results demonstrate that mutant H3K27M can be specifically identified with high specificity and sensitivity using an H3K27M antibody and immunohistochemistry. Use of this antibody in the clinical setting will prove very useful for diagnosis, especially in the context of small biopsies in challenging midline tumors and will help orient care in the context of the extremely poor prognosis associated with this mutation.     

Polar spongioblastoma: A high‐grade glioma that does not contain the IDH1 mutation or 1p/19q LOH

We report a case of an unusual glioma termed “primitive polar spongioblastoma” that displayed characteristic palisading tumor cells at the light microscopic level. The patient was a 52‐year‐old woman who underwent subtotal removal for a left frontotemporal tumor. The palisading pattern was present throughout the tumor. Several glial markers were revealed by immunohistochemical examination, but no neuronal markers were observed. Genetic studies showed O‐6‐methylguanine‐DNA methyltransferase (MGMT) methylation, wild type IDH1, and the absence of 1p/19q loss of heterozygosity (LOH) in the tumor genes. Based on histological and genetic features, this tumor might not be suited to any of neuroepithelial tumor in the recent WHO classification. We consider that cases such as this should be temporarily set under a separate heading and be entrusted to future investigation after more cases have been accumulated.     

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.