The Second NINDS/NIBIB Consensus Meeting to Define Neuropathological Criteria for the Diagnosis of Chronic Traumatic Encephalopathy.

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disorder associated with exposure to head trauma. In 2015, a panel of neuropathologists funded by the NINDS/NIBIB defined preliminary consensus neuropathological criteria for CTE, including the pathognomonic lesion of CTE as "an accumulation of abnormal hyperphosphorylated tau (p-tau) in neurons and astroglia distributed around small blood vessels at the depths of cortical sulci and in an irregular pattern," based on review of 25 tauopathy cases. In 2016, the consensus panel met again to review and refine the preliminary criteria, with consideration around the minimum threshold for diagnosis and the reproducibility of a proposed pathological staging scheme. Eight neuropathologists evaluated 27 cases of tauopathies (17 CTE cases), blinded to clinical and demographic information. Generalized estimating equation analyses showed a statistically significant association between the raters and CTE diagnosis for both the blinded (OR = 72.11, 95% CI = 19.5-267.0) and unblinded rounds (OR = 256.91, 95% CI = 63.6-1558.6). Based on the challenges in assigning CTE stage, the panel proposed a working protocol including a minimum threshold for CTE diagnosis and an algorithm for the assessment of CTE severity as "Low CTE" or "High CTE" for use in future clinical, pathological, and molecular studies.

What Every Neuropathologist Needs to Know: The Muscle Biopsy.

Competence in muscle biopsy evaluation is a core component of neuropathology practice. The practicing neuropathologist should be able to prepare frozen sections of muscle biopsies with minimal artifacts and identify key histopathologic features of neuromuscular disease in hematoxylin and eosin-stained sections as well as implement and interpret a basic panel of additional histochemical, enzyme histochemical, and immunohistochemical stains. Important to everyday practice is a working knowledge of normal muscle histology at different ages, muscle motor units, pitfalls of myotendinous junctions, nonpathologic variations encountered at traditional and nontraditional muscle sites, the pathophysiology of myonecrosis and regeneration, and approaches to distinguish muscular dystrophies from inflammatory myopathies and other necrotizing myopathies. Here, we provide a brief overview of what every neuropathologist needs to know concerning the muscle biopsy.

The spectrum of muscle pathologies: Three decades of experience from a reference laboratory in Saudi Arabia.

BACKGROUND: When investigating patients with a suspected neuromuscular disorder, a muscle biopsy is considered an instrumental tool to reach a definitive diagnosis. There is a paucity of publications that assess the diagnostic utilization and yield of muscle biopsies. We intend to present our experience in this regard over an extended period of more than three decades. METHODS: This is an observational retrospective cohort study in which we collected pathology reports for muscle biopsies diagnosed at our reference lab between 1986 and 2017. RESULTS: We identified a total of 461 cases of muscle biopsy performed, which fulfilled the inclusion criteria. Pediatric cases defined as ≤14 years of age constituted a significant proportion of cases (n = 275, 60%). Normal biopsies were reported in 27% of cases (n = 124), and in 4%, the biopsies were non-diagnostic. The most common pathologies reported were non-specific myopathy (n = 72, 16%), dystrophy (n = 71, 15%), and neurogenic disorders (n = 60, 13%). CONCLUSION: In conclusion, the muscle biopsy will continue to play a crucial role, as a gold standard or as a complementary investigation, in the diagnosis of certain neuromuscular disorders. Increasing the yield and accuracy of muscle pathology should be the main concern and priority to neuropathologists reporting muscle biopsies. In addition, utilizing next-generation sequencing and other molecular techniques have changed the location of muscle biopsy in the algorithm of the diagnosis of neuromuscular disorders. This paper is an urgent call to establish the Saudi Neuropathology Society and the muscle pathology and neuromuscular disorders registry.

Quality assurance in neuropathology: Experiences from the round robin trials on IDH mutation and MGMT promoter methylation testing launched by the Quality Assurance Initiative Pathology (QuIP) in 2018 and 2019.

We here report on the first neuropathological round robin trials initiated by the Quality Assurance Initiative Pathology (QuIP) in Germany in the years 2018 and 2019. Testing services as external laboratory controls were offered for IDH1-R132H immunohistochemistry in 2018 followed by a molecular trial for IDH1 and IDH2 mutations in 2019 including the rare mutational variants. Also in 2019, a trial on MGMT promoter methylation testing was offered. On a national scale, trial offers were well received with around 40 participating institutions. The international announcement of the molecular IDH1/IDH2 mutational trial achieved only moderate European outspread. Success rates in all three trials were excellent (IDH1-R132H immunohistochemistry 2018: 94%, 18 out of 20 possible points required; IDH1/IDH2 mutational status 2019: 100%, 19 out of 20 possible points required; MGMT promoter methylation 2019: 94%, 19 out of 20 possible points required) indicating that quality standards are high in the broad majority of the institutions. Trial participation also involved filling in a questionnaire asking for background information on local testing procedures. We here present a first assessment of the information collected providing unique insights in the landscape of molecular testing in neuropathology. Derived from this information we identify future challenges and provide an outlook on the development of quality assurance in the field of neuropathology.

Diffuse gliomas to date and beyond 2016 WHO Classification of Tumours of the Central Nervous System.

The updated 2016 World Health Organization (WHO) Classification of Tumours of the Central Nervous System (CNS) has incorporated molecular parameters into pathological diagnosis, for the first time in the molecular era. While it has led to the more precise diagnoses of well-understood entities and the better comprehension of less-understood entities, its practical application has also created some concerns whether or not genotypes predominate over phenotypes in tumor diagnostics. In response to these concerns, the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy-Not Official WHO (cIMAPCT-NOW) was established under the sponsorship of the International Society of Neuropathology to provide a forum to evaluate and recommend proposed changes to future CNS tumor classifications. cIMPACT has thus far published five updates on the proposal and clarification of existing and new terms and entities. Also, recent studies have shown that WHO grading based on histology has lost its prognostic relevance, which necessitates novel, improved grading criteria. We herein highlight the current status of clinical application of WHO 2016 classification and cIMPACT proposals, and the future endeavor to incorporate DNA methylation profiling of the CNS tumors for better clinical decision-making to achieve a goal of precision medicine for each patient with brain tumors.

What Every Neuropathologist Needs to Know: Update on cIMPACT-NOW.

World Health Organization (WHO) central nervous system tumor classification represents the primary source of updates on diagnostic classes, grades, and criteria. However, recent and ongoing advances in molecular pathogenesis warrant more rapid integration into clinical practice between WHO updates. To accomplish this, the consortium to inform molecular and practical approaches to CNS tumor taxonomy-not official WHO (cIMPACT-NOW) was established in 2016. Since then, cIMPACT-NOW has convened 3 separate working committees to address classification and grading questions and challenges. This review covers the progress that these working committees have made on their specific topics.

The Utility of Expert Diagnosis in Surgical Neuropathology: Analysis of Consultations Reviewed at 5 National Comprehensive Cancer Network Institutions.

The aim of this study was to characterize the type and degree of discrepancies between non-expert and expert diagnoses of CNS tumors to identify the value of consultations in surgical neuropathology. Neuropathology experts from 5 National Comprehensive Cancer Network (NCCN) member institutions participated in the review of 1281 consultations selected based on inclusion criteria. The consultation cases were re-reviewed at the NCCN headquarters to determine concordance with the original diagnoses. Among all consultations, 249 (19.4%) were submitted for expert diagnoses without final diagnoses from the submitting institution. Within the remaining 1032 patients, the serious/major discrepancy rate was 4.8%, and less serious and minor discrepancies were seen in 19.4% of the cases. The discrepancy rate was higher among patients who were referred to NCCN institutions for consultation compared to those who were referred for treatment only. The discrepancy rates, patient demographics, type of consultations and submitting institutions varied among participating NCCN institutions. Expert consultations identified a subset of cases with significant diagnostic discrepancies, and constituted the initial diagnoses in some cases. These data indicate that expert consultations in glial tumors and all types of pediatric CNS tumors can improve accurate diagnosis and enable appropriate management.

Vascular cognitive impairment neuropathology guidelines (VCING): the contribution of cerebrovascular pathology to cognitive impairment.

There are no generally accepted protocols for post-mortem assessment in cases of suspected vascular cognitive impairment. Neuropathologists from seven UK centres have collaborated in the development of a set of vascular cognitive impairment neuropathology guidelines (VCING), representing a validated consensus approach to the post-mortem assessment and scoring of cerebrovascular disease in relation to vascular cognitive impairment. The development had three stages: (i) agreement on a sampling protocol and scoring criteria, through a series of Delphi method surveys; (ii) determination of inter-rater reliability for each type of pathology in each region sampled (Gwet's AC2 coefficient); and (iii) empirical testing and validation of the criteria, by blinded post-mortem assessment of brain tissue from 113 individuals (55 to 100 years) without significant neurodegenerative disease who had had formal cognitive assessments within 12 months of death. Fourteen different vessel and parenchymal pathologies were assessed in 13 brain regions. Almost perfect agreement (AC2 > 0.8) was found when the agreed criteria were used for assessment of leptomeningeal, cortical and capillary cerebral amyloid angiopathy, large infarcts, lacunar infarcts, microhaemorrhage, larger haemorrhage, fibrinoid necrosis, microaneurysms, perivascular space dilation, perivascular haemosiderin leakage, and myelin loss. There was more variability (but still reasonably good agreement) in assessment of the severity of arteriolosclerosis (0.45-0.91) and microinfarcts (0.52-0.84). Regression analyses were undertaken to identify the best predictors of cognitive impairment. Seven pathologies-leptomeningeal cerebral amyloid angiopathy, large infarcts, lacunar infarcts, microinfarcts, arteriolosclerosis, perivascular space dilation and myelin loss-predicted cognitive impairment. Multivariable logistic regression determined the best predictive models of cognitive impairment. The preferred model included moderate/severe occipital leptomeningeal cerebral amyloid angiopathy, moderate/severe arteriolosclerosis in occipital white matter, and at least one large infarct (area under the receiver operating characteristic curve 77%). The presence of 0, 1, 2 or 3 of these features resulted in predicted probabilities of vascular cognitive impairment of 16%, 43%, 73% or 95%, respectively. We have developed VCING criteria that are reproducible and clinically predictive. Assuming our model can be validated in an independent dataset, we believe that this will be helpful for neuropathologists in reporting a low, intermediate or high likelihood that cerebrovascular disease contributed to cognitive impairment.10.1093/brain/aww214_video_abstractaww214_video_abstract.

Audit of practice in sudden unexpected death in epilepsy (SUDEP) post mortems and neuropathological findings.

AIMS: Sudden unexpected death in epilepsy (SUDEP) is one of the leading causes of death in people with epilepsy. For classification of definite SUDEP, a post mortem (PM), including anatomical and toxicological examination, is mandatory to exclude other causes of death. We audited PM practice as well as the value of brain examination in SUDEP. METHODS: We reviewed 145 PM reports in SUDEP cases from four UK neuropathology centres. Data were extracted for clinical epilepsy details, circumstances of death and neuropathological findings. RESULTS: Macroscopic brain abnormalities were identified in 52% of cases. Mild brain swelling was present in 28%, and microscopic pathologies relevant to cause or effect of seizures were seen in 89%. Examination based on whole fixed brains (76.6% of all PMs), and systematic regional sampling was associated with higher detection rates of underlying pathology (P < 0.01). Information was more frequently recorded regarding circumstances of death and body position/location than clinical epilepsy history and investigations. CONCLUSION: Our findings support the contribution of examination of the whole fixed brain in SUDEP, with high rates of detection of relevant pathology. Availability of full clinical epilepsy-related information at the time of PM could potentially further improve detection through targeted tissue sampling. Apart from confirmation of SUDEP, complete neuropathological examination contributes to evaluation of risk factors as well as helping to direct future research into underlying causes.

Multisite assessment of NIA-AA guidelines for the neuropathologic evaluation of Alzheimer's disease.

INTRODUCTION: Neuropathologic assessment is the current "gold standard" for evaluating the Alzheimer's disease (AD), but there is no consensus on the methods used. METHODS: Fifteen unstained slides (8 brain regions) from each of the 14 cases were prepared and distributed to 10 different National Institute on Aging AD Centers for application of usual staining and evaluation following recently revised guidelines for AD neuropathologic change. RESULTS: Current practice used in the AD Centers Program achieved robustly excellent agreement for the severity score for AD neuropathologic change (average weighted κ = .88, 95% confidence interval: 0.77-0.95) and good-to-excellent agreement for the three supporting scores. Some improvement was observed with consensus evaluation but not with central staining of slides. Evaluation of glass slides and digitally prepared whole-slide images was comparable. DISCUSSION: AD neuropathologic evaluation as performed across AD Centers yields data that have high agreement with potential modifications for modest improvements.