Histopathologic and transmission electron microscopic findings in monkeypox cutaneous lesions.

Background: a few pathologic and ultrastructural findings of monkeypox skin lesions are available in the literature. To integrate such evidence, we aimed to describe the pathologic features of monkeypox skin lesions and to show monkeypox virions by transmission electron microscopy (TEM). Methods: we studied the cutaneous biopsies of three patients affected by monkeypox during the 2022 monkeypox outbreak. Skin biopsies have been collected only from body sites with a recent laboratory-confirmed mpox virus infection, defined by a polymerase chain reaction (PCR) positive result in specimens taken through skin swabs. Results: in all the samples the epidermis showed keratinocytes ballooning degeneration; perivascular/periadnexal infiltrates composed of neutrophils and lymphocytes were observed in the deep dermis. Immunohistochemistry showed that the infiltrate was mostly composed of CD3+ T-cells. TEM revealed monkeypox virus-like particles in various stages of morphogenesis in the dermis and epidermis; virions were interspersed among keratinocytes and within their cytoplasm. At the intracellular level, virions showed a biconcaveshaped central core, surrounded by lateral bodies and an external membrane; they also appeared as rectangular, brick-shaped, or oval particles with eccentric nucleoids. The histologic features of our skin samples confirmed the few other studies on this topic, except for the eosinophilic inclusions of the cytoplasm of keratinocytes (Guarnieri's bodies). Conclusion: the role of molecular biology is crucial for monkeypox diagnosis but when it is not disposable and/or in doubtful cases, skin biopsy and TEM may be helpful to establish the diagnosis.

Disruption of Cerebellar Granular Layer as a Consequence of Germinal Matrix Intraventricular Hemorrhage in Extreme Prematurity: An Acute Direct Mechanism Too?

Cerebellum is an important brain structure for the future development of motor, cognitive, and behavioral abilities in children. This structure undergoes its most significant growth during the third trimester of pregnancy. Prematurity gathers several risk factors for cerebellar impairment and underdevelopment, and among them is ventricular dilatation following germinal matrix intraventricular hemorrhage (GMH-IVH). In this report, we illustrate how this prevalent complication associated with prematurity may induce secondary cerebellar cortical damage. A premature male born by an emergency Caesarean section displayed massive GMH-IVH at brain ultrasound performed after three hours of extrauterine life and died after 18 hours of life, despite maximized vital support. We report a postmortem histopathological specimen of the cerebellar cortex showing the disruption of the external granular layer (EGL) by hemorrhagic content flowing from the supratentorial ventricles into the fourth ventricle and cisterna magna. The expansion of the ventricular system and the presence of blood in the lateral ventricles can cause inflammation and damage to the cerebellar gyri. Experimental models have shown a thinning of the EGL, suggesting that blood surrounding the cerebellum has a harmful action. Additionally, a sudden influx of cerebrospinal fluid from the lateral ventricles may directly contribute to cerebellar damage, indicating that this may be another way in which the cerebellar gyri are impaired during acute severe GMH-IVH. This is the first histopathologically confirmed case of acute disruption in the cerebellar cortex during a GMH-IVH in a premature baby.

Stem-like signatures in human meningioma cells are under the control of CXCL11/CXCL12 chemokine activity.

BACKGROUND: Meningiomas are mainly benign brain tumors, although about 20% of histologically benign cases are clinically aggressive and recur after resection. We hypothesize that meningioma brain invasiveness and recurrence may be related to the presence of cancer stem cells and their high responsiveness to the CXCL12-CXCR4/CXCR7 chemokine axis. The aim of this study was to isolate meningioma stem cells from human samples, characterize them for biological features related to malignant behavior, and to identify the role of CXCR4/CXCR7 in these processes. METHODS: Meningioma stem cells were isolated from patient-derived primary cultures in stem cell-permissive conditions, and characterized for phenotype, self-renewal, proliferation and migration rates, vasculogenic mimicry (VM), and in vivo tumorigenesis, in comparison with differentiated meningioma cells and stem-like cells isolated from normal meninges. These cell populations were challenged with CXCL12 and CXCL11 and receptor antagonists to define the chemokine role in stem cell-related functions. RESULTS: Stem-like cells isolated from meningioma cultures display higher proliferation and migration rates, and VM, as compared to meningioma non-stem cells or cells isolated from normal meninges and were the only tumorigenic population in vivo. In meningioma cells, these stem-like functions were under the control of the CXCR4/CXCR7 chemokine axis. CONCLUSIONS: We report a role for CXCL11 and CXCL12 in the control of malignant features in stem-like cells isolated from human meningioma, providing a possible basis for the aggressive clinical behavior observed in subsets of these tumors. CXCR4/CXCR7 antagonists might represent a useful approach for meningioma at high risk of recurrence and malignant progression.

The spectrum of subclonal TP53 mutations in chronic lymphocytic leukemia: A next generation sequencing retrospective study.

Chronic lymphocytic leukemia (CLL) is a hematological disorder with complex clinical and biological behavior. TP53 mutational status and cytogenetic assessment of the deletion of the corresponding locus (17p13.1) are considered the most relevant biomarkers associated with pharmaco-predictive response, chemo-refractoriness, and worse prognosis in CLL patients. The implementation of Next Generation Sequencing (NGS) methodologies in the clinical laboratory allows for comprehensively analyzing the TP53 gene and detecting mutations with allele frequencies ≤10%, that is, "subclonal mutations". We retrospectively studied TP53 gene mutational status by NGS in 220 samples from 171 CLL patients. TP53 mutations were found in 60/220 (27.3%) samples and 47/171 (27.5%) patients. Interestingly, subclonal mutations could be detected in 31/60 samples (51.7%) corresponding to 25 patients (25/47, 53.2%). We identified 44 distinct subclonal TP53 mutations clustered in the central DNA-binding domain of p53 protein (exons 5-8, codons 133-286). Missense mutations were predominant (>80%), whereas indels, nonsense, and splice site variants were less represented. All subclonal TP53 variants but one [p.(Pro191fs)] were already described in NCI and/or Seshat databases as "damaging" and/or "probably damaging" mutations (38/44, 86% and 6/44, 14%, respectively). Longitudinal samples were available for 37 patients. Almost half of them displayed at least one TP53 mutant subclone, which could be alone (4/16, 25%) or concomitant with other TP53 mutant clonal ones (12/16, 75%); different patterns of mutational dynamics overtimes were documented. In conclusion, utilization of NGS in our "real-life" cohort of CLL patients demonstrated an elevated frequency of subclonal TP53 mutations. This finding indicates the need for precisely identifying these mutations during disease since the clones carrying them may become predominant and be responsible for therapy failures.

Calcifications in diffuse leptomeningeal glioneuronal tumors: a case series.

Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a new rare entity, typically seen in the pediatric population. Classical neuroimaging features at clinical onset include marked subarachnoid/leptomeningeal enhancement and tiny pseudo-cystic lesions along the subpial surface of the neuroaxis, frequently associated with communicating hydrocephalus. However, data on the long-term appearance of this tumor on computed tomography (CT) and magnetic resonance imaging (MRI) are still lacking. We describe a peculiar pattern of progressive leptomeningeal calcifications in three young patients with DLGNT. The calcifications, mainly located in the basal cisterns, sylvian fissures and posterior surface of the thalami, were present at clinical onset in the older subject and appeared about 2 years after clinical onset in the other two. Patients underwent different schemes of chemotherapy, variably associated with craniospinal irradiation and/or bevacizumab. In all cases, calcifications were present before starting craniospinal irradiation and/or treatment with bevacizumab. This novel peculiar pattern of progressive leptomeningeal calcifications expands the imaging phenotype of DLGNT and should be carefully sought, especially in later phases of the disease. Taking into consideration the onset, evolution, and absence of direct relationship with treatments, we hypothesize that calcifications in DLGNTs might be the effect of natural changes in the tumor and its environment.

Adult-onset CblC deficiency: a challenging diagnosis involving different adult clinical specialists.

BACKGROUND: Methylmalonic aciduria and homocystinuria, CblC type (OMIM #277400) is the most common disorder of cobalamin intracellular metabolism, an autosomal recessive disease, whose biochemical hallmarks are hyperhomocysteinemia, methylmalonic aciduria and low plasma methionine. Despite being a well-recognized disease for pediatricians, there is scarce awareness of its adult presentation. A thorough analysis and discussion of cobalamin C defect presentation in adult patients has never been extensively performed. This article reviews the published data and adds a new case of the latest onset of symptoms ever described for the disease. RESULTS: We present the emblematic case of a 45-year-old male, describing the diagnostic odyssey he ventured through to get to the appropriate treatment and molecular diagnosis. Furthermore, available clinical, biochemical and molecular data from 22 reports on cases and case series were collected, resulting in 45 adult-onset CblC cases, including our own. We describe the onset of the disease in adulthood, encompassing neurological, psychiatric, renal, ophthalmic and thromboembolic symptoms. In all cases treatment with intramuscular hydroxycobalamin was effective in reversing symptoms. From a molecular point of view adult patients are usually compound heterozygous carriers of a truncating and a non-truncating variant in the MMACHC gene. CONCLUSION: Adult onset CblC disease is a rare disorder whose diagnosis can be delayed due to poor awareness regarding its presenting insidious symptoms and biochemical hallmarks. To avoid misdiagnosis, we suggest that adult onset CblC deficiency is acknowledged as a separate entity from pediatric late onset cases, and that the disease is considered in the differential diagnosis in adult patients with atypical hemolytic uremic syndromes and/or slow unexplained decline in renal function and/or idiopathic neuropathies, spinal cord degenerations, ataxias and/or recurrent thrombosis and/or visual field defects, maculopathy and optic disc atrophy. Plasma homocysteine measurement should be the first line for differential diagnosis when the disease is suspected. To further aid diagnosis, it is important that genes belonging to the intracellular cobalamin pathway are included within gene panels routinely tested for atypical hemolytic uremic syndrome and chronic kidney disorders.

Spontaneous splenic rupture during induction therapy in acute myeloid leukemia: An unusual case.

Spontaneous splenic rupture (SSR) is a rare life-threatening emergency. In hematological settings, it is uncommon in acute myeloid leukemia (AML). We report an atypical case of SSR in a 73-year-old male with AML where a prompt imaging ultrasound assessment played a key role. Performed noninvasively at bedside, it allowed rapid imaging diagnosis, confirming its essential role even in the presence of hematological disease.

Tumor Immune Microenvironment and Genetic Alterations in Mesothelioma.

Malignant pleural mesothelioma (MPM) is a rare and fatal disease of the pleural lining. Up to 80% of the MPM cases are linked to asbestos exposure. Even though its use has been banned in the industrialized countries, the cases continue to increase. MPM is a lethal cancer, with very little survival improvements in the last years, mirroring very limited therapeutic advances. Platinum-based chemotherapy in combination with pemetrexed and surgery are the standard of care, but prognosis is still unacceptably poor with median overall survival of approximately 12 months. The genomic landscape of MPM has been widely characterized showing a low mutational burden and the impairment of tumor suppressor genes. Among them, BAP1 and BLM are present as a germline inactivation in a small subset of patients and increases predisposition to tumorigenesis. Other studies have demonstrated a high frequency of mutations in DNA repair genes. Many therapy approaches targeting these alterations have emerged and are under evaluation in the clinic. High-throughput technologies have allowed the detection of more complex molecular events, like chromotripsis and revealed different transcriptional programs for each histological subtype. Transcriptional analysis has also paved the way to the study of tumor-infiltrating cells, thus shedding lights on the crosstalk between tumor cells and the microenvironment. The tumor microenvironment of MPM is indeed crucial for the pathogenesis and outcome of this disease; it is characterized by an inflammatory response to asbestos exposure, involving a variety of chemokines and suppressive immune cells such as M2-like macrophages and regulatory T cells. Another important feature of MPM is the dysregulation of microRNA expression, being frequently linked to cancer development and drug resistance. This review will give a detailed overview of all the above mentioned features of MPM in order to improve the understanding of this disease and the development of new therapeutic strategies.

Congenital anomalies of the kidney and urinary tract in a cohort of 280 consecutive patients with Hirschsprung disease.

BACKGROUND: Congenital anomalies of the kidney and urinary tract (CAKUT) have been underestimated in Hirschsprung disease (HSCR). This paper aims at reporting results of patients with HSCR who underwent kidney and urinary tract assessment. METHODS: Patients seen between December 2005 and November 2020 underwent a complete kidney and urinary tract diagnostic workup. Data regarding CAKUT, gender, length of aganglionosis, familial history, HSCR-associated enterocolitis (HAEC), RET genotype, and outcome were collected. RESULTS: Out of 472 patients, 280 completed the workup and represented the focus. Male to female ratio was 3.24:1. Familial cases accounted for 9.8% of patients. RET mutations were detected in 19.8%. We encountered a total of 61 patients with 70 nephrological issues (21.8%), including 28 hypoplasia/dysplasia, 12 hydronephrosis, 11 vesicoureteric reflux, 7 duplex collecting system, 2 kidney agenesis, 2 horseshoe kidney, and 8 miscellanea, involving 91 kidneys without side preponderance (50 right, 41 left). Of these 61 patients, 20 (7.1% of the whole series) required medical or surgical treatment. When comparing patients with and without CAKUT, familial history proved to occur with a significantly lower frequency in the former as did better patient perspectives of outcome. CONCLUSIONS: We confirmed that all diagnostic workups in HSCR should include a complete kidney and urinary tract diagnostic workup. Our study suggests that genes other than RET could play a role in determining CAKUT. Given worse patient perspectives of outcome, CAKUT seems to significantly interfere with quality of life thus confirming the need for early diagnosis and tailored prevention strategies.

Multidisciplinary study of sudden unexpected infant death in Liguria (Italy): a nine-year report.

INTRODUCTION: We conducted a retrospective analysis of cases of sudden unexpected infant death (SUID) referred to the SIDS-ALTE Center of the Liguria Region (Italy) from 2010 to 2018. In all cases, the death scene was inspected, and a multidisciplinary post-mortem evaluation was conducted. Our aim was to analyze the epidemiological data and etiological distribution. EVIDENCE ACQUISITION: We examined 15 cases initially classified as sudden infant death. EVIDENCE SYNTHESIS: In all cases, the death was initially unexplained. Seven cases involved males and eight involved females. Their mean age was 67.47 days; the youngest victim was 2 days old, while the oldest was 8.5 months (253 days). In 7 cases, the post-mortem analysis showed an infection of lung. In 4 cases, the prone position of the infant during sleep was identified as a risk factor. Only in one case the cause of death remains unexplained, and it was classified as sudden infant death syndrome II according to San Diego Classification. CONCLUSIONS: In the forensic approach to cases of SUID, it is always important to conduct a thorough multidisciplinary investigation. In order to avoid procedural errors that might compromise the post-mortem investigation, it is necessary to consider the medical and social history of both mother and child, in addition to the circumstances of the death. Moreover, a complete pediatric post-mortem examination and multidisciplinary discussion are required in order to identify potentially important causative or contributory factors.

Minimally Invasive Redo Pull-Throughs in Hirschsprung Disease.

Introduction: To reoperate a patient with Hirschsprung disease (HSCR) can be technically demanding and most surgeons would resort to conventional laparotomy. This article describes a series of patients with postoperative obstructive symptoms who underwent minimally invasive redo pull-throughs (MIRPT) (either laparoscopic or robotic) to assess the role of minimally invasive surgery (MIS) in complicated HSCR patients. Patients and Methods: All consecutive HSCR patients with postoperative obstructive symptoms, who underwent MIRPT with fast track concepts of care between January 2012 and January 2020, have been included. Data regarding indications, surgical details, complications, and outcome have been compared to those of a series of patients who underwent conventional laparotomic redo. Results: Sixteen patients were included. Male to female ratio was 4.3:1. Median age at surgery was 78 months. Eleven patients underwent laparoscopic redo and 5 underwent robotic redo. Median length of follow-up was 49 months. Reasons for redoing were transition zone pull-through, residual aganglionosis, anastomotic retraction or leak, rectal diverticulum, and refractory anastomotic stricture. No major intraoperative complication occurred. No conversion to laparotomy was required. One patient experienced cuff stricture requiring laparoscopic release. Two patients reported bouts of enterocolitis postoperatively. Compared to classic laparotomic redo pull-throughs (49 patients with complete data), overall complications were significantly less frequent, accounting for 1 and 21 events, respectively (6% versus 43%) (P = .0067). Continence after a median of 21 months postoperatively scored excellent to good in 9 out of 12 patients, who were assessed on this regard (75%), without statistically significant differences. Conclusions: MIRPT proved to be effective and safe in HSCR patients complaining postoperative obstructive symptoms. Robotic surgery could play a crucial. Our study confirms that complicated HSCR cases can be safely managed by means of MIS, applying concepts of fast track care to serve the best for our patients.

Moyamoya vasculopathy shows a genetic mutational gradient decreasing from East to West.

BACKGROUND: Moyamoya disease (MMD) is a chronic, occlusive cerebrovascular disease characterized by bilateral steno-occlusive changes at the terminal portion of the internal carotid arteries and an abnormal vascular network at the base of the brain determining stroke in children. Patients with a similar vasculopathy and associated conditions are affected by the moyamoya syndrome (MMS). Most of the studies focused on MMD were carried out on East-Asian population. Ring Finger 213 (RNF213) has been identified as the strongest susceptibility gene for MMD in East-Asian people. Overall, 74.5% of the East-Asian patients carry the founder variant p.Arg4810Lys of RNF213 never reported in Caucasians. A different genetic landscape among the diverse ethnic populations seems to exist. METHODS: We sequenced the coding sequence region of RNF213, TGFB1 and PDGFRB in 21 ethnically homogeneous Italian children with moyamoya; comprehensive sequencing data are available from parents of eight of them. The analyses were carried out by NGS on Thermo-fisher PGM platform. We also performed a comprehensive review of the literature about the variations of these three genes in Caucasian patients. RESULTS: Several new variants of RNF213 gene were detected, in particular, two new pathogenic mutations on RNF213 (p.Trp4677Leu and p.Cys4017Ser) were identified in one MMS case and in one MMD case, respectively. Moreover, in a MMS case a new probably causing disease mutation p.Pro1063Thr of PDGFRB was detected. CONCLUSIONS: The genetic susceptibility of Asian moyamoya vasculopathy seems to differ from the Caucasian disease. No additional differences seem to exist between MMD and MMS.

A novel knock-in mouse model of cryopyrin-associated periodic syndromes with development of amyloidosis: Therapeutic efficacy of proton pump inhibitors.

BACKGROUND: Cryopyrin-associated periodic syndromes (CAPS) are a group of autoinflammatory diseases linked to gain-of-function mutations in the NOD-like receptor family, pyrin domain containing 3 (NLRP3) gene, which cause uncontrolled IL-1ß secretion. Proton pump inhibitors (PPIs), which are commonly used as inhibitors of gastric acid production, also have anti-inflammatory properties, protect mice from sepsis, and prevent IL-1ß secretion by monocytes from patients with CAPS. OBJECTIVE: We sought to develop a novel Nlrp3 knock-in (KI) mouse model of CAPS to study amyloidosis, a severe CAPS complication, and test novel therapeutic approaches. METHODS: We generated KI mice by engineering the N475K mutation, which is associated with the CAPS phenotype, into the mouse Nlrp3 gene. KI and wild-type mice received PPIs or PBS intraperitoneally and were analyzed for survival, inflammation, cytokine secretion, and amyloidosis development. RESULTS: Mutant Nlrp3 KI mice displayed features that recapitulate the immunologic and clinical phenotype of CAPS. They showed systemic inflammation with high levels of serum proinflammatory cytokines, inflammatory infiltrates in various organs, and amyloid deposits in the spleen, liver, and kidneys. Toll-like receptor stimulated macrophages from KI mice secreted high levels of IL-1ß, IL-18, and IL-1α but low amounts of IL-1 receptor antagonist. Treatment of KI mice with PPIs had a clear clinical effect, showing a reduction in inflammatory manifestations, regression of amyloid deposits, and normalization of proinflammatory and anti-inflammatory cytokine production by macrophages. CONCLUSION: Nlrp3 KI mice displayed a CAPS phenotype with many characteristics of autoinflammation, including amyloidosis. The therapeutic effectiveness of PPIs associated with a lack of toxicity indicates that these drugs could represent relevant adjuvants to the anti-IL-1 drugs in patients with CAPS and other IL-1-driven diseases.

Atypical Extraventricular Neurocytoma: Imaging Findings of Disregarded Diagnosis.

Extraventricular neurocytoma (EVN) is an exceedingly rare brain tumor. The radiologic and histologic features of EVN are insidious, and only a few reports and clinical cases describe the characteristics of the tumor, which may show different presentations. We report a case of atypical EVN in a 23-year-old man; Computed Tomography and Magnetic Resonance Imaging features of the mass are described, and differential diagnosis are illustrated. In light of the high variability of imaging presentation, the definitive diagnosis of EVN remains histologic. Although some cases have already been reported in the literature, we believe that the description of our case could be useful to increase the knowledge of this insidious tumor, which has gained recognition only over the past 2 decades and should be included in the differential diagnosis in young patients who present brain tumors.

Hirschsprung disease and Down syndrome: From the reappraisal of risk factors to the impact of surgery.

INTRODUCTION: The association of Hirschsprung disease (HSCR) and Down Syndrome (DS) is not uncommon (HSCR+DS). This paper aims at reporting the results of a 24-year series focusing on surgical approach, complications and long term outcome. MATERIALS AND METHODS: The notes of all patients admitted with a diagnosis of HSCR+DS have been retrospectively reviewed. Surgical details, intraoperative complications, long term issues and functional outcome have been recorded. The results have been compared to those of patients without DS and were assessed based on surgical approach. RESULTS: A total of 23 HSCR+DS out of a series of 385 HSCR (6%) have been included. Preoperative enterocolitis (HAEC) was reported by 32%. Associated anomalies were detected in more than half of the patients. In particular, Congenital Heart Defects (CHDs) were reported by 57%. Postoperative complications (mostly symptomatic anal sphincter achalasia) were experienced by 55%. Constipation was experienced by 30%; severe continence issues, by 53%. One patient suffering from severe CHDs died. With regard to complications, only symptomatic anal achalasia requiring intrasphincteric BoTox injection was significantly more frequent in HSCR+DS (30% vs 10%, p = 0.0071). Similarly, continence proved to be significantly worse in HSCR+DS. DISCUSSION: With the exception of symptomatic anal achalasia, HSCR+DS patients proved not to have a higher likelihood of complications compared to HSCR alone. On the other hand, functional results in the long term are worse. As a consequence, long term follow up and personalized rehabilitation programs are warranted for this delicate subset of HSCR patients. LEVEL OF EVIDENCE: Level III.

Role of Immunohistochemistry in the Identification of Supratentorial C11ORF95-RELA Fused Ependymoma in Routine Neuropathology.

Ependymomas (EPs) are tumors of the brain and spinal cord constituting ∼10% of the childhood central nervous system neoplasms and about 30% in children aged <3 years. Their anatomic distribution varies according to the age, with those arising in the supratentorial (ST) compartment, spinal cord being more common in older children and adults, and those at the infratentorial location are more common and occurring more frequently in infants and children. Recently, molecular classification of EP subgroups has been proposed and a supratentorial ependymoma subgroup characterized by RELA-fusion genes (ST-EP-RELA) has been established. It would be useful to define a standardized, robust method for the diagnosis of these relevant fusion genes. We used real-time polymerase chain reaction, conventional real-time polymerase chain reaction, and Sanger sequencing to characterize RELA fusion status in formalin-fixed paraffin-embedded samples from 42 ST-EPs (12 adults and 30 pediatric). We tested p65/RELA and L1CAM protein immunohistochemistry for their ability to predict RELA-fusion status. We reviewed clinical data to assess significant associations in this anatomic subgroup. Of the 42 patients, we identified RELA-fusion genes in 17 cases. L1CAM immunostaining displayed 94% sensitivity, 76% specificity, 73% positive predictive value (PPV), 95% negative predictive value (NPV). The p65/RELA immunostaining displayed 100% sensitivity, 92% specificity, 89.5% PPV, 100% NPV. Concordant double immunostaining improves PPV to 92.5% and maintains 100% NPV. Immunohistochemistry using both p65/RELA and L1CAM antibodies is valuable for ST-EP-RELA diagnosis: the negativity with both antibodies consistently predicts the absence of RELA fusions, whereas verification of fusion transcripts by molecular analyses is warranted only in single-positive or double-positive staining cases.

Sudden infant death syndrome: the role of multidisciplinary teams. Experience of the SIDS-ALTE Center of Liguria Region.

The aim of this paper was to highlight the importance of a multidisciplinary and multiprofessional management of SIDS for a complete approach to this tragic event. Both biomedical and psychosocial aspects are evaluated, focusing on the impact of SIDS diagnosis on the family. The paper describes the organization of our team, composed of a network of specialists involved in both prevention and management of SIDS. A protocol is proposed to improve SIDS diagnosis and management. In our team, the clinical pediatrician is the coordinator of specialists and the mediator between the family and the other specialists, thanks to his direct relationship with parents.

Molecularly defined diffuse leptomeningeal glioneuronal tumor (DLGNT) comprises two subgroups with distinct clinical and genetic features.

Diffuse leptomeningeal glioneuronal tumors (DLGNT) represent rare CNS neoplasms which have been included in the 2016 update of the WHO classification. The wide spectrum of histopathological and radiological features can make this enigmatic tumor entity difficult to diagnose. In recent years, large-scale genomic and epigenomic analyses have afforded insight into key genetic alterations occurring in multiple types of brain tumors and provide unbiased, complementary tools to improve diagnostic accuracy. Through genome-wide DNA methylation screening of > 25,000 tumors, we discovered a molecularly distinct class comprising 30 tumors, mostly diagnosed histologically as DLGNTs. Copy-number profiles derived from the methylation arrays revealed unifying characteristics, including loss of chromosomal arm 1p in all cases. Furthermore, this molecular DLGNT class can be subdivided into two subgroups [DLGNT methylation class (MC)-1 and DLGNT methylation class (MC)-2], with all DLGNT-MC-2 additionally displaying a gain of chromosomal arm 1q. Co-deletion of 1p/19q, commonly seen in IDH-mutant oligodendroglioma, was frequently observed in DLGNT, especially in DLGNT-MC-1 cases. Both subgroups also had recurrent genetic alterations leading to an aberrant MAPK/ERK pathway, with KIAA1549:BRAF fusion being the most frequent event. Other alterations included fusions of NTRK1/2/3 and TRIM33:RAF1, adding up to an MAPK/ERK pathway activation identified in 80% of cases. In the DLGNT-MC-1 group, age at diagnosis was significantly lower (median 5 vs 14 years, p < 0.01) and clinical course less aggressive (5-year OS 100, vs 43% in DLGNT-MC-2). Our study proposes an additional molecular layer to the current histopathological classification of DLGNT, of particular use for cases without typical morphological or radiological characteristics, such as diffuse growth and radiologic leptomeningeal dissemination. Recurrent 1p deletion and MAPK/ERK pathway activation represent diagnostic biomarkers and therapeutic targets, respectively-laying the foundation for future clinical trials with, e.g., MEK inhibitors that may improve the clinical outcome of patients with DLGNT.