PATZ1-Rearranged Tumors of the Central Nervous System: Characterization of a Pediatric Series of Seven Cases.

PATZ1-rearranged sarcomas are well-recognized tumors as part of the family of round cell sarcoma with EWSR1-non-ETS fusions. Whether PATZ1-rearranged central nervous system (CNS) tumors are a distinct tumor type is debatable. We thoroughly characterized a pediatric series of PATZ1-rearranged CNS tumors by chromosome microarray analysis (CMA), DNA methylation analysis, gene expression profiling and, when frozen tissue is available, optical genome mapping (OGM). The series consisted of 7 cases (M:F=1.3:1, 1-17 years, median 12). On MRI, the tumors were supratentorial in close relation to the lateral ventricles (intraventricular or iuxtaventricular), preferentially located in the occipital lobe. Two major histologic groups were identified: one (4 cases) with an overall glial appearance, indicated as "neuroepithelial" (NET) by analogy with the corresponding methylation class (MC); the other (3 cases) with a predominant spindle cell sarcoma morphology, indicated as "sarcomatous" (SM). A single distinct methylation cluster encompassing both groups was identified by multidimensional scaling analysis. Despite the epigenetic homogeneity, unsupervised clustering analysis of gene expression profiles revealed 2 distinct transcriptional subgroups correlating with the histologic phenotypes. Interestingly, genes implicated in epithelial-mesenchymal transition and extracellular matrix composition were enriched in the subgroup associated to the SM phenotype. The combined use of CMA and OGM enabled the identification of chromosome 22 chromothripsis in all cases suitable for the analyses, explaining the physical association of PATZ1 to EWSR1 or MN1. Six patients are currently disease-free (median follow-up 30 months, range 12-92). One patient of the SM group developed spinal metastases at 26 months from diagnosis and is currently receiving multimodal therapy (42 months). Our data suggest that PATZ1-CNS tumors are defined by chromosome 22 chromothripsis as causative of PATZ1 fusion, show peculiar MRI features (eg, relation to lateral ventricles, supratentorial frequently posterior site), and, although epigenetically homogenous, encompass 2 distinct histologic and transcriptional subgroups.

Aggressive PitNETs and Potential Target Therapies: A Systematic Review of Molecular and Genetic Pathways.

Recently, advances in molecular biology and bioinformatics have allowed a more thorough understanding of tumorigenesis in aggressive PitNETs (pituitary neuroendocrine tumors) through the identification of specific essential genes, crucial molecular pathways, regulators, and effects of the tumoral microenvironment. Target therapies have been developed to cure oncology patients refractory to traditional treatments, introducing the concept of precision medicine. Preliminary data on PitNETs are derived from preclinical studies conducted on cell cultures, animal models, and a few case reports or small case series. This study comprehensively reviews the principal pathways involved in aggressive PitNETs, describing the potential target therapies. A search was conducted on Pubmed, Scopus, and Web of Science for English papers published between 1 January 2004, and 15 June 2023. 254 were selected, and the topics related to aggressive PitNETs were recorded and discussed in detail: epigenetic aspects, membrane proteins and receptors, metalloprotease, molecular pathways, PPRK, and the immune microenvironment. A comprehensive comprehension of the molecular mechanisms linked to PitNETs' aggressiveness and invasiveness is crucial. Despite promising preliminary findings, additional research and clinical trials are necessary to confirm the indications and effectiveness of target therapies for PitNETs.

Tumor heterogeneity and tumor-microglia interactions in primary and recurrent IDH1-mutant gliomas.

The isocitrate dehydrogenase (IDH) gene is recurrently mutated in adult diffuse gliomas. IDH-mutant gliomas are categorized into oligodendrogliomas and astrocytomas, each with unique pathological features. Here, we use single-nucleus RNA and ATAC sequencing to compare the molecular heterogeneity of these glioma subtypes. In addition to astrocyte-like, oligodendrocyte progenitor-like, and cycling tumor subpopulations, a tumor population enriched for ribosomal genes and translation elongation factors is primarily present in oligodendrogliomas. Longitudinal analysis of astrocytomas indicates that the proportion of tumor subpopulations remains stable in recurrent tumors. Analysis of tumor-associated microglia/macrophages (TAMs) reveals significant differences between oligodendrogliomas, with astrocytomas harboring inflammatory TAMs expressing phosphorylated STAT1, as confirmed by immunohistochemistry. Furthermore, inferred receptor-ligand interactions between tumor subpopulations and TAMs may contribute to TAM state diversity. Overall, our study sheds light on distinct tumor populations, TAM heterogeneity, TAM-tumor interactions in IDH-mutant glioma subtypes, and the relative stability of tumor subpopulations in recurrent astrocytomas.

Neurochemical Differences between 1p/19q Codeleted and Noncodeleted IDH-mutant Gliomas by in Vivo MR Spectroscopy.

Background Noninvasive identification of glioma subtypes is important for optimizing treatment strategies. Purpose To compare the in vivo neurochemical profiles between isocitrate dehydrogenase (IDH) 1-mutant 1p/19q codeleted gliomas and their noncodeleted counterparts measured by MR spectroscopy at 3.0 T with a point-resolved spectroscopy (PRESS) sequence optimized for D-2-hydroxyglutarate (2HG) detection. Materials and Methods Adults with IDH1-mutant gliomas were retrospectively included for this study from two university hospitals (inclusion period: January 2015 to July 2016 and September 2019 to June 2021, respectively) based on availability of 1p/19q codeletion status and a PRESS acquisition optimized for 2HG detection (echo time, 97 msec) at 3.0 T before any treatment. Spectral analysis was performed using LCModel and a simulated basis set. Metabolite quantification was performed using the water signal as a reference and correcting for water and metabolite longitudinal and transverse relaxation time constants. Concentration ratios were computed using total creatine (tCr) and total choline. A two-tailed unpaired t test was used to compare metabolite concentrations obtained in codeleted versus noncodeleted gliomas, accounting for multiple comparisons. Results Thirty-one adults (mean age, 39 years ± 8 [SD]; 19 male) were included, and 19 metabolites were quantified. Cystathionine concentration was higher in codeleted (n = 13) than noncodeleted (n = 18) gliomas when quantification was performed using the water signal or tCr as references (2.33 mM ± 0.98 vs 0.93 mM ± 0.94, and 0.34 mM ± 0.14 vs 0.14 mM ± 0.14, respectively; both P < .001). The sensitivity and specificity of PRESS to detect codeletion by means of cystathionine quantification were 92% and 61%, respectively. Other metabolites did not show evidence of a difference between groups (P > .05). Conclusion Higher cystathionine levels were detected in IDH1-mutant 1p/19q codeleted gliomas than in their noncodeleted counterparts with use of a PRESS sequence optimized for 2HG detection. Of 19 metabolites quantified, only cystathionine showed evidence of a difference in concentration between groups. Clinical trial registry no. NCT01703962 © RSNA, 2023 See also the editorial by Lin in this issue.

Human iPSC-Derived 3D Hepatic Organoids in a Miniaturized Dynamic Culture System.

The process of identifying and approving a new drug is a time-consuming and expensive procedure. One of the biggest issues to overcome is the risk of hepatotoxicity, which is one of the main reasons for drug withdrawal from the market. While animal models are the gold standard in preclinical drug testing, the translation of results into therapeutic intervention is often ambiguous due to interspecies differences in hepatic metabolism. The discovery of human induced pluripotent stem cells (hiPSCs) and their derivatives has opened new possibilities for drug testing. We used mesenchymal stem cells and hepatocytes both derived from hiPSCs, together with endothelial cells, to miniaturize the process of generating hepatic organoids. These organoids were then cultivated in vitro using both static and dynamic cultures. Additionally, we tested spheroids solely composed by induced hepatocytes. By miniaturizing the system, we demonstrated the possibility of maintaining the organoids, but not the spheroids, in culture for up to 1 week. This timeframe may be sufficient to carry out a hypothetical pharmacological test or screening. In conclusion, we propose that the hiPSC-derived liver organoid model could complement or, in the near future, replace the pharmacological and toxicological tests conducted on animals.

The "candy wrapper" of the pituitary gland: a road map to the parasellar ligaments and the medial wall of the cavernous sinus.

PURPOSE: The anatomy of the medial wall of the cavernous sinus (MWCS) and parasellar ligaments (PLs) has acquired increasing importance in endoscopic endonasal (EE) surgery of the cavernous sinus (CS), including resection of the MWCS in functioning pituitary adenomas (FPAs). Although anatomical studies have been published, it represents a debated topic due to their complex morphology. The aim is to offer a description of the PLs that originate from the MWCS and reach the lateral wall of the cavernous sinus (LWCS), proposing the "candy wrapper" model. The relationships between the neurovascular structures and histomorphological aspects were investigated. METHODS: Forty-two CSs from twenty-one human heads were studied. Eleven specimens were used for EE dissection; five underwent a microscopic dissection. Five specimens were used for histomorphological analysis. RESULTS: Two groups of PLs with a fan-shaped appearance were encountered. The anterior group included the periosteal ligament (55% sides) and the carotico-clinoid complex (100% sides), formed by the anterior horizontal and the carotico-clinoid ligaments. The posterior group was formed by the posterior horizontal (78% sides), and the inferior hypophyseal ligament (34% sides). The periosteal ligament originated inferiorly from the MWCS, reaching the periosteal dura. The anterior horizontal ligament was divided in a superior and inferior branch. The superior one continued as the carotid-oculomotor membrane, and the inferior branch reached the CN VI. The carotico-clinoid ligament between the middle and anterior clinoid was ossified in 3 sides. The posterior horizontal ligament was related to the posterior genu and ended at the LWCS. The inferior hypophyseal ligament followed the homonym artery. The ligaments related to the ICA form part of the adventitia. CONCLUSION: The "candy wrapper" model adds further details to the previous descriptions of the PLs. Understanding this complex anatomy is essential for safe CS surgery, including MWCS resection for FPAs.

Targeting mTOR Pathway in PTEN Deleted Newly Isolated Chordoma Cell Line.

Chordomas are rare primary malignant tumours of notochordal origin usually arising along the axial skeleton with particular predilection of the skull base and sacrococcygeal region. Albeit usually slow-growing, chordomas can be aggressive mostly depending on their invasive behaviour and according to different histotypes and molecular alterations, including TBXT duplication and SMARCB1 homozygous deletion. Partial or complete PTEN deficiency has also been observed. PTEN is a negative regulator of the Akt/mTOR pathway and hyperactivation of Akt/mTOR in cells lacking PTEN expression contributes to cell proliferation and invasiveness. This pathway is targeted by mTOR inhibitors and the availability of in vitro models of chordoma cells will aid in further investigating this issue. However, isolation and maintenance of chordoma cell lines are challenging and PTEN-deleted chordoma cell lines are exceedingly rare. Hereby, we established and characterized a novel human PTEN-deleted chordoma cell line (CH3) from a primary skull base chordoma. Cells exhibited morphological and molecular features of the parent tumour, including PTEN loss and expression of Brachyury and EMA. Moreover, we investigated the activation of the mTOR pathway and cell response to mTOR inhibitors. CH3 cells were sensitive to Rapamycin treatment suggesting that mTOR inhibitors may represent a valuable option for patients suffering from PTEN-deleted chordomas.

Exceptionally rare IDH1-mutant adult medulloblastoma with concurrent GNAS mutation revealed by in vivo magnetic resonance spectroscopy and deep sequencing.

Medulloblastoma (MB) is the most common malignant brain tumor occurring in childhood and rarely found in adults. Based on transcriptome profile, MB are currently classified into four major molecular groups reflecting a considerable biological heterogeneity: WNT-activated, SHH-activated, group 3 and group 4. Recently, DNA methylation profiling allowed the identification of additional subgroups within the four major molecular groups associated with different clinic-pathological and molecular features. Isocitrate dehydrogenase-1 and 2 (IDH1 and IDH2) mutations have been described in several tumors, including gliomas, while in MB are rarely reported and not routinely investigated. By means of magnetic resonance spectroscopy (MRS), we unequivocally assessed the presence the oncometabolite D-2-hydroxyglutarate (2HG), a marker of IDH1 and IDH2 mutations, in a case of adult MB. Immunophenotypical work-up and methylation profiling assigned the diagnosis of MB, subclass SHH-A, and molecular testing revealed the presence of the non-canonical somatic IDH1(p.R132C) mutation and an additional GNAS mutation, also rarely described in MB. To the best of our knowledge, this is the first reported case of MB simultaneously harboring both mutations. Of note, tumor exhibited a heterogeneous phenotype with a tumor component displaying glial differentiation, with robust GFAP expression, and a component with conventional MB features and selective presence of GNAS mutation, suggesting co-existence of two different major tumor subclones. These findings drew attention to the need for a deeper genetic characterization of MB, in order to get insights into their biology and improve stratification and clinical management of the patients. Moreover, our results underlined the importance of performing MRS for the identification of IDH mutations in non-glial tumors. The use of throughput molecular profiling analysis and advanced medical imaging will certainly increase the frequency with which tumor entities with rare molecular alterations will be identified. Whether these findings have any specific therapeutic implications or prognostic relevance requires further investigations.

New pathogenic variants in ARMC5 gene in a series of Italian patients affected by primary bilateral macronodular adrenocortical hyperplasia (PBMAH).

BACKGROUND: To perform genetic screening for ARMC5 gene germline pathogenic variants in patients with primary bilateral macronodular adrenal hyperplasia (PBMAH). SUBJECTS AND METHODS: In a group of 10 PBMAH patients, we performed complete sequencing of the coding region of the ARMC5 gene and MLPA analysis for large deletion detection. In subjects with the ARMC5 variant, we searched ARMC5 gene somatic variants on tumor samples. RESULTS: Among 10 PBMAH patients, we identified four ARMC5 germline variants (40%). One variant, c:174dupC p.Glu59Argfs*44, was already known; one variant p.Gly323Asp, was already reported and classified as likely disease-causing VUS (class 3-4); two variants p.Leu596Arg and p.Arg811Pro, were never reported before. For p.Gly323Asp and p.Arg811Pro, we identified second deleterious variants at the somatic level, enforcing the possible pathogenic effect of germline variants. CONCLUSIONS: Our results underscore the importance of performing genetic testing also in sporadic PBMAH patients and broaden the spectrum of molecular variants involved in PBMAH syndrome.

Lactotroph PitNET/adenoma associated to granulomatous hypophysitis in a patient with Crohn's disease: A case report.

Granulomatous hypophysitis is a rare and poorly understood condition. Although certain cases are treated as primary pituitary autoimmune disorders, rare cases may be associated with pituitary neuroendocrine tumours (PitNETs) and systemic inflammatory diseases. Here, we report a case of a 47-year-old man that underwent endoscopic trans-sphenoidal excision of a pituitary mass diagnosed as PitNET. On histologic evaluation, the neoplasm showed an admixture of granulomas with extensive inflammatory infiltrate and lactotroph PitNET/adenoma. Careful anamnestic examination revealed a diagnosis of Crohn's disease 20 years prior. Although rarely done, both PitNET and Crohn's disease may be associated with granulomatous hypophysitis, and our patient had both conditions. During the 6-year follow-up, PitNETs and hypophysitis did not recur, while Crohn's disease was only partially controlled by medical therapy. To our knowledge, this is the first description of association of granulomatous hypophysitis, PitNET and Crohn's disease.

Treatment strategy for vertebral metastases from anal squamous cell carcinoma: a comprehensive literature review and case report.

Purpose/aim of the study: Purpose/aim of the study:Central nervous system (CNS), skull, and vertebral metastases from anal squamous cell carcinoma (SCC) are an exceedingly rare entity. We report the first case of multiple vertebral metastases from a primary anal SCC with the aim of define a target therapeutic strategy.Case presentation: We present the case of a 68-year-old male admitted to our hospital for acute exacerbation chronic low back pain and left L2 radiculopathy. His medical history included the diagnosis of a human papilloma virus related, moderately differentiated anal SCC (cT3N0M0-stage IIB), treated with standard chemoradiotherapy regimen two years earlier. Spinal magnetic resonance imaging revealed an isolated solid lesion of the L2 vertebral body. After the surgical removal, histopathological examination confirmed the diagnosis of moderately differentiated SCC. At 1-month radiological follow-up, two new lesions at the level of T7 to T11 were identified. Additional chemotherapy and radiotherapy for metastatic localization of L2, T7, and T11 were administered. Two-year follow-up demonstrated a radiologically and clinically well-controlled disease. To supplement our case, a systematic literature review on the CNS, skull, and vertebral metastases and their treatments has been performed.Conclusion: Despite several proposed guidelines for the management of vertebral metastases, at present, a universally accepted treatment strategy for vertebral metastases from anal SCC has not been defined. Based on our clinical experience and literature review, in case of vertebral metastases from anal SCC, a prompt and aggressive, local and systemic, and multimodal treatment of the vertebral lesions may be paramount to improve the patient outcomes.

Adult type diffuse gliomas in the new 2021 WHO Classification.

Adult-type diffuse gliomas represent a group of highly infiltrative central nervous system tumors with a prognosis that significantly varies depending on the specific subtype and histological grade. Traditionally, adult-type diffuse gliomas have been classified based on their morphological features with a great interobserver variability and discrepancy in patient survival even within the same histological grade. Over the last few decades, advances in molecular profiling have drastically changed the diagnostic approach and classification of brain tumors leading to the development of an integrated morphological and molecular classification endowed with a more clinically relevant value. These concepts were largely anticipated in the revised fourth-edition of WHO classification of central nervous system tumors published in 2016. The fifth-edition (WHO 2021) moved molecular diagnostics forward into a full integration of molecular parameters with the histological features into an integrative diagnostic approach. Diagnosis of adult type diffuse gliomas, IDH mutant and IDH-wildtype has been simplified by introducing revised diagnostic and grading criteria. In this review, we will discuss the most recent updates to the classification of adult-type diffuse gliomas and summarize the essential diagnostic keys providing a practical guidance to pathologists.

Case Report: 18F-PSMA PET/CT Scan in Castration Resistant Prostate Cancer With Aggressive Neuroendocrine Differentiation.

The development of a neuroendocrine phenotype as a mechanism of resistance to hormonal treatment is observed in up to 20% of advanced prostate cancer patients. High grade neuroendocrine prostate cancer (NEPC) is associated to poor prognosis and the therapeutic armamentarium is restricted to platinum-based chemotherapy. Prostate-specific membrane antigen (PSMA)-based positron emission tomography (PET)/computed tomography (CT) imaging has recently emerged as a potential new standard for the staging of prostate cancer and PSMA-based radioligand therapy (RLT) as a therapeutic option in advanced metastatic castration resistant prostate cancer (mCRPC). PSMA-based theranostic is not currently applied in the staging and treatment of NEPC since PSMA expression on neuroendocrine differentiated cells was shown to be lost. In this case series, we present 3 consecutive mCRPC patients with histologically proven high grade neuroendocrine differentiation who underwent PSMA-PET/CT and surprisingly showed high tracer uptake. This observation stimulates further research on the use of PSMA-based theranostic in the management of NEPC.

Diagnosis and Treatment of Pineal Region Tumors in Adults: A EURACAN Overview.

Pineal region tumors are rare intracranial tumors, accounting for less than 1% of all adult intracranial tumor lesions. These lesions represent a histologically heterogeneous group of tumors. Among these tumors, pineal parenchymal tumors and germ cell tumors (GCT) represent the most frequent types of lesions. According to the new WHO 2021 classification, pineal parenchymal tumors include five distinct histotypes: pineocytoma (PC), pineal parenchymal tumors of intermediate differentiation (PPTID), papillary tumor of the pineal region (PTPR), pinealoblastoma (PB), and desmoplastic myxoid tumor of the pineal region, SMARCB1-mutant; GCTs include germinoma, embryonal carcinoma, yolk sac tumor, choriocarcinoma, teratoma, mixed GCTs. Neuroradiological assessment has a pivotal role in the diagnostic work-up, surgical planning, and follow-up of patients with pineal masses. Surgery can represent the mainstay of treatment, ranging from biopsy to gross total resection, yet pineal region tumors associated with obstructive hydrocephalus may be surgically managed via ventricular internal shunt or endoscopic third ventriculostomy. Radiotherapy remains an essential component of the multidisciplinary treatment approach for most pineal region tumors; however, treatment volumes depend on the histological subtypes, grading, extent of disease, and the combination with chemotherapy. For localized germinoma, the current standard of care is chemotherapy followed by reduced-dose whole ventricular irradiation plus a boost to the primary tumor. For pinealoblastoma patients, postoperative radiation has been associated with higher overall survival. For the other pineal tumors, the role of radiotherapy remains poorly studied and it is usually reserved for aggressive (grade 3) or recurrent tumors. The use of systemic treatments mainly depends on histology and prognostic factors such as residual disease and metastases. For pinealoblastoma patients, chemotherapy protocols are based on various alkylating or platinum-based agents, vincristine, etoposide, cyclophosphamide and are used in association with radiotherapy. About GCTs, their chemosensitivity is well known and is based on cisplatin or carboplatin and may include etoposide, cyclophosphamide, or ifosfamide prior to irradiation. Similar regimens containing platinum derivatives are also used for non-germinomatous GCTs with very encouraging results. However, due to a greater understanding of the biology of the disease's various molecular subtypes, new agents based on targeted therapy are expected in the future. On behalf of the EURACAN domain 10 group, we reviewed the most important and recent developments in histopathological characteristics, neuro-radiological assessments, and treatments for pineal region tumors.

The influence of cystathionine on neurochemical quantification in brain tumor in vivo MR spectroscopy.

PURPOSE: To evaluate the ability of the PRESS sequence (TE  = 97 ms, optimized for 2-hydroxyglutarate detection) to detect cystathionine in gliomas and the effect of the omission of cystathionine on the quantification of the full neurochemical profile. METHODS: Twenty-three subjects with a glioma were retrospectively included based on the availability of both MEGA-PRESS and PRESS acquisitions at 3T, and the presence of the cystathionine signal in the edited MR spectrum. In eight subjects, the PRESS acquisition was performed also in normal tissue. Metabolite quantification was performed using LCModel and simulated basis sets. The LCModel analysis for the PRESS data was performed with and without cystathionine. RESULTS: All subjects with glioma had detectable cystathionine levels >1 mM with Cramér-Rao lower bounds (CRLB) <15%. The mean cystathionine concentrations were 3.49 ± 1.17 mM for MEGA-PRESS and 2.20 ± 0.80 mM for PRESS data. Cystathionine concentrations showed a significant correlation between the two MRS methods (r = 0.58, p = .004), and it was not detectable in normal tissue. Using PRESS, 19 metabolites were quantified with CRLB <50% for more than half of the subjects. The metabolites that were significantly (p < .0028) and mostly affected by the omission of cystathionine were aspartate, betaine, citrate, γ-aminobutyric acid (GABA), and serine. CONCLUSIONS: Cystathionine was detectable by PRESS in all the selected gliomas, while it was not detectable in normal tissue. The omission from the spectral analysis of cystathionine led to severe biases in the quantification of other neurochemicals that may play key roles in cancer metabolism.

Sellar metastasis from clear cell sarcoma: Description of the first case.

Metastases to the sellar region and pituitary gland are rare and usually occur in advanced cancers, commonly breast and lung adenocarcinomas. Metastases from sarcomas to the pituitary gland are extremely rare. Here, we report the case of a 52-year-old man who had undergone surgery and radiotherapy for a clear cell sarcoma (CCS) of the knee at age of 42. The patient underwent resection of 2 distinct metastatic lung nodules 9 years later. During follow-up, he developed a persistent headache and diabetes insipidus. MRI revealed a sellar and suprasellar lesion, which was removed with an endoscopic trans-sphenoidal approach. Histopathology was consistent with CSS metastasis. At 2-year follow-up, there was no evidence of local recurrence in the sella, while a single brain metastasis was documented, together with other deposits in the paravertebral and pelvic muscles. CCS is a rare, aggressive neoplasm usually involving the deep soft tissue of the extremities, including trunk or limb girdles, and extensive surgical removal, along with adjuvant chemo- and radiotherapy, significantly prolongs survival. Nevertheless, prognosis remains poor, mainly due to frequent local recurrences and eventually distant metastases, usually within regional lymph nodes, lung, and bone. To the best of our knowledge, this is the first description of a sellar metastasis from CCS.

Leptomeningeal dissemination of anaplastic medullary cone astrocytoma: an unexpected findings in a patient with leptomeningeal enhancement and clinical history of multiple myeloma.

We report a challenging autopsy case with an insidious clinical presentation with diffuse lepto- and pachymeningeal enhancement in a context of a complex clinical history. Clinical features, neuroradiological and anamnestic data were consistent with central nervous system (CNS) dissemination of a previously known lambda restricted multiple myeloma. Autoptic findings allowed to discard this hypothesis. Unexpectedly, CNS sampling revealed an atypical glial cell proliferation within the sacral meningeal layers. No primary intraparenchymal CNS glial lesion was found. Findings supported the final diagnosis of anaplastic astrocytoma IDH1-wild type of the medullary cone with diffuse leptomeningeal and cerebrospinal fluid (CSF) dissemination. This occurrence represents an extremely rare condition itself, further complicated by the clinical history of the patient that led to formulate the most probable diagnosis of localization of the primary known disease. This autopsy case underlines that patients previously diagnosed with a primary tumor are not only at risk of recurrences or progression of the original disease, but they must be always accurately checked for eventual onset of a second tumor, including rare conditions such as gliomatosis.

Thymic Epithelial Cell Alterations and Defective Thymopoiesis Lead to Central and Peripheral Tolerance Perturbation in MHCII Deficiency.

Major Histocompatibility Complex (MHC) class II (MHCII) deficiency (MHCII-D), also known as Bare Lymphocyte Syndrome (BLS), is a rare combined immunodeficiency due to mutations in genes regulating expression of MHCII molecules. MHCII deficiency results in impaired cellular and humoral immune responses, leading to severe infections and autoimmunity. Abnormal cross-talk with developing T cells due to the absence of MHCII expression likely leads to defects in thymic epithelial cells (TEC). However, the contribution of TEC alterations to the pathogenesis of this primary immunodeficiency has not been well characterized to date, in particular in regard to immune dysregulation. To this aim, we have performed an in-depth cellular and molecular characterization of TEC in this disease. We observed an overall perturbation of thymic structure and function in both MHCII-/- mice and patients. Transcriptomic and proteomic profiling of murine TEC revealed several alterations. In particular, we demonstrated that impairment of lymphostromal cross-talk in the thymus of MHCII-/- mice affects mTEC maturation and promiscuous gene expression and causes defects of central tolerance. Furthermore, we observed peripheral tolerance impairment, likely due to defective Treg cell generation and/or function and B cell tolerance breakdown. Overall, our findings reveal disease-specific TEC defects resulting in perturbation of central tolerance and limiting the potential benefits of hematopoietic stem cell transplantation in MHCII deficiency.

EBF1 is expressed in pericytes and contributes to pericyte cell commitment.

Early B-cell factor-1 (EBF1) is a transcription factor with an important role in cell lineage specification and commitment during the early stage of cell maturation. Originally described during B-cell maturation, EBF1 was subsequently identified as a crucial molecule for proper cell fate commitment of mesenchymal stem cells into adipocytes, osteoblasts and muscle cells. In vessels, EBF1 expression and function have never been documented. Our data indicate that EBF1 is highly expressed in peri-endothelial cells in both tumor vessels and in physiological conditions. Immunohistochemistry, quantitative reverse transcription polymerase chain reaction (RT-qPCR) and fluorescence-activated cell sorting (FACS) analysis suggest that EBF1-expressing peri-endothelial cells represent bona fide pericytes and selectively express well-recognized markers employed in the identification of the pericyte phenotype (SMA, PDGFRß, CD146, NG2). This observation was also confirmed in vitro in human placenta-derived pericytes and in human brain vascular pericytes (HBVP). Of note, in accord with the key role of EBF1 in the cell lineage commitment of mesenchymal stem cells, EBF1-silenced HBVP cells showed a significant reduction in PDGFRß and CD146, but not CD90, a marker mostly associated with a prominent mesenchymal phenotype. Moreover, the expression levels of VEGF, angiopoietin-1, NG2 and TGF-ß, cytokines produced by pericytes during angiogenesis and linked to their differentiation and activation, were also significantly reduced. Overall, the data suggest a functional role of EBF1 in the cell fate commitment toward the pericyte phenotype.

H3K27me3 immunostaining is diagnostic and prognostic in diffuse gliomas with oligodendroglial or mixed oligoastrocytic morphology.

Oligodendroglioma is defined by IDH mutation and 1p/19q codeletion. The latter is mutually exclusive to ATRX immunohistochemical loss and has been recently associated with the loss of H3K27me3 immunostaining. We aimed to assess the diagnostic and prognostic value of H3K27me3 immuno-expression in diffuse gliomas with oligodendroglial or mixed oligoastrocytic morphology. H3K27me3 immunostaining was performed in 69 diffuse gliomas with oligodendroglial (n = 62) or oligoastrocytic (n = 7) morphology. The integration with routinely assessed IDH mutations, ATRX immunostaining, and 1p/19q codeletion classified these cases as 60 oligodendroglial and 9 astrocytic. H3K27me3 was lost in 58/60 oligodendrogliomas with retained (n = 47) or non-conclusive (n = 11) ATRX staining, 3/6 IDH-mutant astrocytomas with ATRX loss, and 3/3 IDH-wt astrocytomas. H3K27me3 was retained in 2/60 oligodendrogliomas with retained ATRX, and in 3/6 IDH-mutant astrocytomas, two of which had lost and one retained ATRX. The combination of H3K27me3 and ATRX immunostainings with IDH mutational status correctly classified 55/69 (80%) cases. In IDH-mutant gliomas, ATRX loss indicates astrocytic phenotype, while ATRX retention and H3K27me3 loss identify oligodendroglial phenotype. Only 14 (20%) IDH-mutant cases with retained ATRX and H3K27me3 or inconclusive ATRX immunostaining would have requested 1p/19q codeletion testing to be classified. Furthermore, H3K27me3 retention was associated with significantly shorter relapse-free survival (P < 0.0001), independently from IDH mutation or 1p/19q codeletion (P < 0.005). Our data suggest that adding H3K27me3 immunostaining to the diagnostic workflow of diffuse gliomas with oligodendroglial or mixed morphology is useful for drastically reducing the number of cases requiring 1p/19q codeletion testing and providing relevant prognostic information.