Severe acute myositis and myocarditis on initiation of 6-weekly pembrolizumab post-COVID-19 mRNA vaccination.

We describe three cases of critical acute myositis with myocarditis occurring within 22 days of each other at a single institution, all within 1 month of receiving the initial cycle of the anti-PD-1 drug pembrolizumab. Analysis of T cell receptor repertoires from peripheral blood and tissues revealed a high degree of clonal expansion and public clones between cases, with several T cell clones expanded within the skeletal muscle putatively recognizing viral epitopes. All patients had recently received a COVID-19 mRNA booster vaccine prior to treatment and were positive for SARS-CoV2 Spike antibody. In conclusion, we report a series of unusually severe myositis and myocarditis following PD-1 blockade and the COVID-19 mRNA vaccination.

Metastatic meningioma: a case series and systematic review.

BACKGROUND: Meningiomas are the most common primary intracranial tumor. While the majority of meningiomas are benign, rarely they can metastasize extracranially. There is a need for a more comprehensive review of these patients to improve our understanding of this rare phenomenon and its prevalence globally. Here we describe our institution's experience of patients presenting with metastatic meningiomas. We further perform a systematic review of the existing literature to explore common features of this rare manifestation of meningioma and review the efficacy of current treatments. METHODS: We performed a retrospective clinical review of all adult patients with metastatic meningioma managed at our institution over the past 20 years, identifying 6 patients. We then performed a systematic review of cases of metastatic meningioma in the literature ranging from the years 1886 to 2022. A descriptive analysis was then conducted on the available data from 1979 onward, focusing on the grade and location of the primary tumor as well as the latency period to, and location of, the metastasis. RESULTS: In total, we analyzed 155 cases. Fifty-four percent of patients initially presented with a primary meningioma located in the convexity. The most common site of metastasis was the lung. Risk factors associated with a shorter time to metastasis were male sex and a high initial grade of the tumor. Regarding treatment, the addition of chemotherapy was the most common adjunct to the standard management of surgery and radiotherapy. Despite an exhaustive review we were unable to identify effective treatments. The majority of published cases came from centers situated in high-income countries (84%) while only 16% came from lower- and middle-income countries. CONCLUSIONS: Metastatic meningiomas pose a pertinent, and likely underestimated, clinical challenge within modern neurosurgery. To optimize management, timely identification of these patients is important. More research is needed to explore the mechanisms underlying these tumors to better guide the development of effective screening and management protocols. However, screening of each meningioma patient is not feasible, and at the heart of this challenge is the inability to control the primary disease. Ultimately, a consensus is needed as to how to correctly screen for and manage these patients; genomic and epigenomic approaches could hold the answer to finding druggable targets.

AL amyloidosis presenting with isolated lumbosacral radiculoplexus neuropathy.

A 45-year-old man presented with an isolated sciatic mononeuropathy, which then evolved into a lumbosacral radiculoplexus neuropathy. His initial symptoms included lower limb pain, sensory disturbance and later weakness, without autonomic dysfunction. Neurophysiology suggested a postganglionic neuropathy. MR and ultrasound scans of the thighs showed right sciatic nerve thickening, and CSF analysis showed albuminocytological dissociation. Fluorodeoxyglucose positron emission tomography (FDG PET) was unremarkable. He then developed orthostatic symptoms and urinary disturbance, and was found to have an IgM paraprotein. Fat aspirate, cardiac and whole-body imaging found no amyloid deposition, and genetic testing for transthyretin amyloidosis was negative. A bone marrow biopsy was unremarkable. However, neuropathology review of a proximal, fascicular nerve biopsy identified a lambda chain-restricted plasma cell population with positive Congo red staining, leading to a diagnosis of peripheral nerve restricted amyloid light amyloidosis. We discuss the diagnostic approach to this case from the perspectives of neurology, neurophysiology, radiology and neuropathology.

Predictors of pituitary tumour behaviour: an analysis from long-term follow-up in 2 tertiary centres.

OBJECTIVES: To determine the clinical utility of assessment of tumour invasion, markers of proliferation, and the French clinicopathological classification in pituitary tumour prognostication. METHODS: This is a retrospective evaluation of adult patients undergoing pituitary surgery at Oxford University and St Vincent's Hospitals, between 1989 and 2016, with at least 12 months of clinical data. Invasion was assessed radiologically, proliferative markers (Ki67, mitotic count, p53) by immunohistochemistry. Tumours were graded according to the clinicopathological classification. Intra- and interlaboratory variability of histopathology reporting was evaluated. OUTCOMES: (1) Tumour recurrence (radiological or reintervention ≥12 months postoperatively) and/or (2) "aggressive behaviour" (≥4 interventions and/or invasive tumour with recurrence/reintervention between 12 and 24 months postoperatively). RESULTS: A total of 386 patients were included, age at surgery was 56 (interquartile range [IQR] 41-67) years, 54% were male, and median follow-up was 90 months (range 44-126). Tumours were predominantly clinically nonfunctioning (252, 65%), with overall 53% invasive, and 10% that demonstrated ≥2 proliferative marker positivity. Recurrence was predicted by invasiveness (hazards ratio [HR] 1.6 [1.10-2.37], P .02), elevated mitotic count (HR 2.17 [1.21-3.89], P .01), grade (2b vs 1a HR 2.32 [1.06-5.03], P .03), and absence of gross total resection (HR 3.70 [1.72-8.00], P .01). Clinically defined aggressiveness was associated with elevated Ki67, mitotic count, and invasiveness. Ki67 reporting methodologies showed moderate correlation across laboratories (Phi 0.620), whereas p53 reporting reproducibility was poor (Phi 0.146). CONCLUSIONS: Proliferative markers, including Ki67 and mitotic count, but not p53, are important in predicting the development of aggressive pituitary tumour behaviour.

Utilising clinical parameters to improve the selection of nerve biopsy candidates.

BACKGROUND: Peripheral nerve biopsy is a valuable final diagnostic tool; however, histopathological results can be non-diagnostic. AIMS: We aim to identify quality improvement measures by evaluating the pre-biopsy assessment and diagnostic yield of specific histopathological diagnosis. METHODS: This was a retrospective study based on 10 years of experience with peripheral nerve biopsies at a single centre. Clinical data were obtained regarding pre-biopsy history, examination, serum and cerebrospinal fluid (CSF) investigations, neurophysiology and peripheral nerve imaging. Based upon a histopathological outcome, patients were grouped into vasculitis, granulomatous and infiltrative (diagnostic) group, or a comparison group of non-specific axonal neuropathy and normal (non-specific/normal) group. RESULTS: From a cohort of 64 patients, 21 (32.8%) were included in the diagnostic group and 30 (46.9%) in the non-specific/normal group. Clinical parameters associated with the diagnostic group were shorter history (mean 10.2 months vs 38.1), stepwise progression (81% vs 20%), neuropathic pain (85.7% vs 56.7%), vasculitic rash (23.8% vs 0%), mononeuritis multiplex (57.1% vs 10%), asymmetry (90.5% vs 60%), raised white cell count (47.6% vs 16.7%), myeloperoxidase antibody (19.1% vs 0%) and abnormal peripheral nerve imaging (33.3% vs 10%). CONCLUSION: Selection of patients undergoing nerve biopsy requires careful consideration of clinical parameters, including peripheral nerve imaging. Several quality improvement measures are proposed to improve yield of clinically actionable information from nerve biopsy.

Cryopreservation of Malus and Pyrus Wild Species in the 'Fruit Genebank' in Dresden-Pillnitz, Germany.

A unique and valuable diversity of the Malus and Pyrus wild species germplasm is maintained ex situ in field collections in the 'Fruit Genebank' in Dresden-Pillnitz, Germany. (1) Background: The establishment of a duplicate collection is necessary to preserve this material safely from abiotic and biotic stress factors. (2) Methods: Two different techniques, cryopreservation using dormant buds and PVS2 vitrification using in vitro shoot tips, were applied and compared. (3) Results: In Malus altogether 180 accessions belonging to 32 species were processed with an average recovery rate of 39% within ten years using the dormant bud method. Accessions, 116 in number, achieved the criterion of 40% recovery which was 64.44% of all accessions tested. In the case of Pyrus germplasm a total of 35 accessions of 21 species and both techniques for cryopreservation were tested. In the results of these experiments the PVS2 method led to better results compared to the dormant bud method. (4) Conclusions: In Malus the dormant bud technique will be the method of choice for the future to build up the duplicate collection. Further experiments using both techniques are planned in the future to make a final decision for Pyrus.

Genetic and Pomological Determination of the Trueness-to-Type of Sweet Cherry Cultivars in the German National Fruit Genebank.

Genebank collections preserve many old cultivars with ancient breeding history. However, often, cultivars with synonymous or incorrect names are maintained in multiple collections. Therefore, pomological and genetic characterization is an essential prerequisite for confirming trueness-to-type of cultivars in gene bank collections. In our study, 1442 single sweet cherry (Prunus avium L.) trees of the German Fruit Genebank were evaluated according to their trueness-to-type. For this purpose, pomological analysis was performed, in which the accessions were assigned totheir historical cultivar names. The pomological identifications were based on several historical reference sources, such as fruit references from historical cherry cultivar and fruit-stone collections, as well as historical pomological literature sources. In addition, the cherry trees were genetically analyzed for cultivar identity using 16 SSR markers. Based on pomological characterization and genetic analysis for the majority of the trees (86%), cultivar authenticity could be confirmed. Most markers were highly discriminating and powerful for cultivar identification. The cherry collection showed a high degree of genetic diversity, with an expected heterozygosity He = 0.67. Generally, high genetic admixture between cultivars of different geographic origin and year of origin was obtained after STRUCTURE analysis, demonstrating the extensive exchange of genetic information between cherry cultivars in the collection over time. However, the phylogenetic tree calculated by DARwin reflected the geographic origin of selected cherry cultivars. After parentage analysis with CERVUS, paternity could not be confirmed for three cultivars, indicating the necessity of further pedigree analysis for these cultivars. The results of our study underlined the general importance of evaluating the authenticity of cultivars in genebank collections based on genetic and pomological characterization.

Autophagy in non-immune-mediated rhabdomyolysis: Assessment of p62 immunohistochemistry.

INTRODUCTION/AIMS: p62 immunochemistry (IHC) has been shown to aid diagnosis with distinct patterns of muscle fiber staining observed in some inflammatory, hereditary, and degenerative myopathies, such as immune-mediated necrotizing myopathy (IMNM). The pattern of p62 staining may help narrow the pathological differential diagnosis of rhabdomyolysis. However, there is a lack of information on the pattern of p62 IHC in non-immune-mediated rhabdomyolysis. In this study we aim to describe histopathological findings in non-immune-mediated rhabdomyolysis, with particular emphasis on the pattern of p62 IHC. METHODS: We retrospectively reviewed the histopathological features of patients with a confirmed diagnoses of non-immune-mediated rhabdomyolysis referred to our center. RESULTS: Five patients were identified. Rhabdomyolysis was determined to be due to statin-associated toxicity in three patients, alcohol overuse in one patient, and intensive exercise in one patient. All patients showed increased numbers of necrotic and regenerating muscle fibers. Diffuse and finely granular sarcoplasmic positive p62 staining was present in scattered non-necrotic muscle fibers in all patients. DISCUSSION: Disturbance of autophagy appears to be a common mechanism in non-immune-mediated rhabdomyolysis. Our results show p62 IHC is sensitive but lacks specificity. Therefore, the pattern of p62 staining does not distinguish non-immune-mediated rhabdomyolysis from histopathologically similar IMNM.

Modern Solutions for Ancient Pathogens: Direct Pathogen Sequencing for Diagnosis of Lepromatous Leprosy and Cerebral Coenurosis.

Microbes unculturable in vitro remain diagnostically challenging, dependent historically on clinical findings, histology, or targeted molecular detection. We applied whole-genome sequencing directly from tissue to diagnose infections with mycobacteria (leprosy) and parasites (coenurosis). Direct pathogen DNA sequencing provides flexible solutions to diagnosis of difficult pathogens in diverse contexts.

Acute small fiber neuropathy after Oxford-AstraZeneca ChAdOx1-S vaccination: A report of three cases and review of the literature.

Small fiber neuropathy usually presents with gradual and progressive chronic length-dependent pain. Acute small fiber neuropathy is rarely reported. Three patients with acute onset neuropathic pain after Oxford-AstraZeneca ChAdOx1-S vaccination are described. Two patients were identified at the Oxford University NHS Foundation Trust, Oxford, UK and one patient in Red de Salud UC Christus, Santiago, Chile. All patients underwent a clinical assessment that included a detailed neurological examination, laboratory investigations, nerve conduction studies, thermal threshold testing, and skin biopsy for intra-epidermal nerve fiber density. Patients seen in Oxford underwent MRI of the brain and spinal cord. Cerebrospinal analysis was not performed. Neuropathic symptoms (burning pain, dysaesthesias) developed in the hands and feet within 2 weeks of vaccination. On clinical examination, there was pinprick and thermal hyposensitivity in the area of neuropathic pain. Laboratory investigation, nerve conduction tests, sympathetic skin responses, and MRI showed no relevant abnormalities. Thermal thresholds were abnormal and intra-epidermal nerve fiber density in the lower leg was reduced. In two cases symptoms persist after several months. Three cases of definite acute small fiber neuropathy after Oxford-AstraZeneca ChAdOx1-S vaccination are described. At follow up, neuropathic pain was present in two of the patients.

Towards smart and sustainable development of modern berry cultivars in Europe.

Fresh berries are a popular and important component of the human diet. The demand for high-quality berries and sustainable production methods is increasing globally, challenging breeders to develop modern berry cultivars that fulfill all desired characteristics. Since 1994, research projects have characterized genetic resources, developed modern tools for high-throughput screening, and published data in publicly available repositories. However, the key findings of different disciplines are rarely linked together, and only a limited range of traits and genotypes has been investigated. The Horizon2020 project BreedingValue will address these challenges by studying a broader panel of strawberry, raspberry and blueberry genotypes in detail, in order to recover the lost genetic diversity that has limited the aroma and flavor intensity of recent cultivars. We will combine metabolic analysis with sensory panel tests and surveys to identify the key components of taste, flavor and aroma in berries across Europe, leading to a high-resolution map of quality requirements for future berry cultivars. Traits linked to berry yields and the effect of environmental stress will be investigated using modern image analysis methods and modeling. We will also use genetic analysis to determine the genetic basis of complex traits for the development and optimization of modern breeding technologies, such as molecular marker arrays, genomic selection and genome-wide association studies. Finally, the results, raw data and metadata will be made publicly available on the open platform Germinate in order to meet FAIR data principles and provide the basis for sustainable research in the future.

Mitochondrial dysfunction in anti-3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) immune-mediated necrotising myopathy.

Mitochondrial dysfunction is a plausible cause of muscle fibre damage in a number of myopathies including immune-mediated necrotising myopathy. However, histopathological evidence of mitochondrial dysfunction is not often described in immune-mediated necrotising myopathy and, when present, it is often attributed to patient age. The purpose of this study was to describe features of mitochondrial dysfunction on muscle biopsy in anti-3­hydroxy-3-methylglutaryl-CoA reductase immune-mediated necrotising myopathy and explore whether these features are age-related. In this observational case control study, a statistically significant increase in the number of muscle fibres with increased lipid content (p = 0.004) and cytochrome c oxidase-negative/succinate dehydrogenase-positive fibres (p = 0.037) in anti-3­hydroxy-3-methylglutaryl-coenzyme immune-mediated necrotising myopathy was found compared to age-matched controls. Therefore, histopathological features of mitochondrial dysfunction are more frequent in anti-3­hydroxy-3-methylglutaryl-coenzyme immune-mediated necrotising myopathy than aged-matched controls and therefore, may be contributing to the pathogenesis.

SSR-Based Analysis of Genetic Diversity and Structure of Sweet Cherry (Prunus avium L.) from 19 Countries in Europe.

Sweet cherry (Prunus avium L.) is a temperate fruit species whose production might be highly impacted by climate change in the near future. Diversity of plant material could be an option to mitigate these climate risks by enabling producers to have new cultivars well adapted to new environmental conditions. In this study, subsets of sweet cherry collections of 19 European countries were genotyped using 14 SSR. The objectives of this study were (i) to assess genetic diversity parameters, (ii) to estimate the levels of population structure, and (iii) to identify germplasm redundancies. A total of 314 accessions, including landraces, early selections, and modern cultivars, were monitored, and 220 unique SSR genotypes were identified. All 14 loci were confirmed to be polymorphic, and a total of 137 alleles were detected with a mean of 9.8 alleles per locus. The average number of alleles (N = 9.8), PIC value (0.658), observed heterozygosity (Ho = 0.71), and expected heterozygosity (He = 0.70) were higher in this study compared to values reported so far. Four ancestral populations were detected using STRUCTURE software and confirmed by Principal Coordinate Analysis (PCoA), and two of them (K1 and K4) could be attributed to the geographical origin of the accessions. A N-J tree grouped the 220 sweet cherry accessions within three main clusters and six subgroups. Accessions belonging to the four STRUCTURE populations roughly clustered together. Clustering confirmed known genealogical data for several accessions. The large genetic diversity of the collection was demonstrated, in particular within the landrace pool, justifying the efforts made over decades for their conservation. New sources of diversity will allow producers to face challenges, such as climate change and the need to develop more sustainable production systems.

Leucine-Rich Glioma-Inactivated 1 versus Contactin-Associated Protein-like 2 Antibody Neuropathic Pain: Clinical and Biological Comparisons.

Pain is a under-recognized association of leucine-rich glioma-inactivated 1 (LGI1) and contactin-associated protein-like 2 (CASPR2) antibodies. Of 147 patients with these autoantibodies, pain was experienced by 17 of 33 (52%) with CASPR2- versus 20 of 108 (19%) with LGI1 antibodies (p = 0.0005), and identified as neuropathic in 89% versus 58% of these, respectively. Typically, in both cohorts, normal nerve conduction studies and reduced intraepidermal nerve fiber densities were observed in the sampled patient subsets. In LGI1 antibody patients, pain responded to immunotherapy (p = 0.008), often rapidly, with greater residual patient-rated impairment observed in CASPR2 antibody patients (p = 0.019). Serum CASPR2 antibodies, but not LGI1 antibodies, bound in vitro to unmyelinated human sensory neurons and rodent dorsal root ganglia, suggesting pathophysiological differences that may underlie our clinical observations. ANN NEUROL 2021;90:683-690.

Towards a Joint International Database: Alignment of SSR Marker Data for European Collections of Cherry Germplasm.

The objective of our study was the alignment of microsatellite or simple sequence repeat (SSR) marker data across germplasm collections of cherry within Europe. Through the European Cooperative program for Plant Genetic Resources ECPGR, a number of European germplasm collections had previously been analysed using standard sets of SSR loci. However, until now these datasets remained unaligned. We used a combination of standard reference genotypes and ad-hoc selections to compile a central dataset representing as many alleles as possible from national datasets produced in France, Great Britain, Germany, Italy, Sweden and Switzerland. Through the comparison of alleles called in data from replicated samples we were able to create a series of alignment factors, supported across 448 different allele calls, that allowed us to align a dataset of 2241 SSR profiles from six countries. The proportion of allele comparisons that were either in agreement with the alignment factor or confounded by null alleles ranged from 67% to 100% and this was further improved by the inclusion of a series of allele-specific adjustments. The aligned dataset allowed us to identify groups of previously unknown matching accessions and to identify and resolve a number of errors in the prior datasets. The combined and aligned dataset represents a significant step forward in the co-ordinated management of field collections of cherry in Europe.

Evaluation of Scab and Mildew Resistance in the Gene Bank Collection of Apples in Dresden-Pillnitz.

A set of 680 apple cultivars from the Fruit Gene bank in Dresden Pillnitz was evaluated for the incidence of powdery mildew and scab in two consecutive years. The incidence of both scab and powdery mildew increased significantly in the second year. Sixty and 43 cultivars with very low incidence in both years of scab and powdery mildew, respectively, were analysed with molecular markers linked to known resistance genes. Thirty-five cultivars were identified to express alleles or combinations of alleles linked to Rvi2, Rvi4, Rvi6, Rvi13, Rvi14, or Rvi17. Twenty of them, modern as well as a few traditional cultivars known before the introduction or Rvi6 from Malus floribunda 821, amplified the 159 bp fragment of marker CH_Vf1 that is linked to Rvi6. Alleles linked to Pl1, Pld, or Plm were expressed from five cultivars resistant to powdery mildew. Eleven cultivars were identified to have very low susceptibility to both powdery mildew and scab. The information on resistance/susceptibility of fruit genetic resources towards economically important diseases is important for breeding and for replanting traditional cultivars. Furthermore, our work provides a well-defined basis for the discovery of undescribed, new scab, and powdery mildew resistance.

Sporadic late-onset nemaline myopathy: a case report of a treatable cause of cardiac failure.

BACKGROUND: Sporadic late-onset nemaline myopathy (SLONM) is a rare, acquired, adult-onset myopathy, characterized by proximal muscle weakness and the pathognomonic feature of nemaline rods in muscle fibres. Sporadic late-onset nemaline myopathy is associated with cardiac pathology in case reports and small case series, but the severity of cardiac disease is generally mild and rarely requires specific treatment. This case report describes severe heart failure as an early feature of SLONM, which responded to specific treatments, and highlights SLONM as a potentially reversible cause of heart failure. CASE SUMMARY: A 65-year-old woman presented with progressive muscle weakness and a dramatic loss of muscle bulk in her thighs, followed by progressive effort breathlessness over an 18-month period. She required a wheelchair to ambulate. A diagnosis of SLONM was made on histopathological assessment of a muscle biopsy along with electron microscopy. An echocardiogram showed a severely dilated and impaired left ventricle. She was treated with standard heart failure medications and autologous stem cell transplantation, which resulted in improvement of both her cardiac and muscle function, and allowed her to walk again and resume near-normal functional performance status. DISCUSSION: Cardiomyopathy can be a relatively early and life-threatening feature of SLONM and even in severe cases can be effectively treated with standard heart failure medications and autologous stem cell transplantation.

18FDG PET-CT in sporadic Creutzfeldt-Jakob disease, correlated with MRI and histology.

We present a case of sporadic Creutzfeldt-Jakob disease with profoundly abnormal 18fluoro-deoxy-glucose positron emission tomography with computed tomography (FDG PET-CT) at an early stage, and correlate this with the clear findings at magnetic resonance imaging and also postmortem histology. Prion diseases are rare but important causes of cognitive impairment. The role of FDG PET-CT is discussed, along with other investigations such as electroencephalography and cerebro-spinal fluid analyses.

Genetic integrity is still maintained in natural populations of the indigenous wild apple species Malus sylvestris (Mill.) in Saxony as demonstrated with nuclear SSR and chloroplast DNA markers.

Malus sylvestris (Mill.) is the only indigenous wild apple species in Central Europe. Agriculture, forestry, and urbanization increasingly endanger Malus sylvestris natural habitats. In addition, the risks of cross-hybridization associated with increase in the cultivation of the domesticated apple Malus × domestica (Borkh.) threaten the genetic integrity of M. sylvestris. The present study investigated the number of hybrids, genetic diversity, and genetic structure of 292 putative M. sylvestris that originate from five different natural M. sylvestris populations in Saxony, Germany. All samples were genetically analyzed using nine nuclear microsatellite markers (ncSSR) and four maternally inherited chloroplast markers (cpDNA) along with 56 apple cultivars commonly cultivated in Saxony. Eighty-seven percent of the wild apple accessions were identified as pure M. sylvestris. The cpDNA analysis showed six private haplotypes for M. sylvestris, whereas three haplotypes were present in M. sylvestris and M. × domestica. The analysis of molecular variance (AMOVA) resulted in a moderate (ncSSR) and great (cpDNA) variation among pure M. sylvestris and M. × domestica individuals indicating a low gene flow between both species. The genetic diversity within the pure M. sylvestris populations was high with a weak genetic structure between the M. sylvestris populations indicating an unrestricted genetic exchange between these M. sylvestris populations. The clear distinguishing of M. sylvestris and M. ×domestica confirms our expectation of the existence of pure M. sylvestris accessions in this area and supports the argument for the implementation of preservation measures to protect the M. sylvestris populations in Saxony.

Correlation of Alzheimer Disease Neuropathologic Staging with Amyloid and Tau Scintigraphic Imaging Biomarkers.

PET neuroimaging of amyloid-ß (Aß) provides an in vivo biomarker for pathologic changes associated with Alzheimer disease (AD). Aß-targeted agents have been approved by the Food and Drug Administration, with additional agents, most notably targeting tau, currently under clinical investigation and one approved in May 2020. These agents, along with nonscintigraphic biomarkers from blood and cerebrospinal fluid, have provided an opportunity to investigate the pathogenesis, prodromal changes, and time course of the disease in living individuals. The current understanding is that the neuropathologic changes of the AD continuum begin up to 25 y before the onset of clinical symptomatology. The opportunities afforded by in vivo biomarkers of AD, whether by serum, cerebrospinal fluid examination or PET, have transformed the design of AD therapeutic trials by shifting focus to the preclinical stages of disease. Future disease-modifying therapies, should they be forthcoming, will rely heavily on the use of approved biomarkers or biomarkers currently under investigation to confirm the presence of target pathology. Understanding the progressive neuropathologic changes that occur in AD-and how scintigraphic findings relate to these changes-will help the interpreting physician to fully appreciate the implications of the scintigraphic findings and provide a basis to interpret the examinations. The recently adopted National Institute on Aging-Alzheimer Association guidelines define postmortem AD neuropathologic changes as a composite score based on 3 elements. These elements are the extent of involvement (spread) by cerebral Aß based on the progression model defined by the Thal Aß phases, the extent of involvement (spread) by neurofibrillary tangles (composed of hyperphosphorylated tau proteins) based on the progression model defined by Braak, and the Consortium to Establish a Registry for Alzheimer's Disease score, which describes the density of neuritic plaques based on certain key locations in the neocortex. This paper will review the 3 elements that define the National Institute on Aging-Alzheimer's Association scoring system and discusses current evidence on how these elements relate to findings based on Aß and tau PET scintigraphy.