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Antisynthetase syndrome is recently recognized as one of the major entities of autoimmune myositis. The prototype of antisynthetase syndrome is anti-Jo-1 antibody associated syndrome while the syndromes associated with non-Jo-1 antisynthetase antibodies are clinically and pathologically less recognized. Identifying a non-Jo-1 antisynthetase syndrome patient could be challenging because the full panel serology test may not be available at the time of diagnosis in addition to technical difficulty especially for anti-OJ antibody detection. This study aimed to characterize the muscle pathology and explore the utility of myofiber HLA-DR expression for the diagnosis of antisynthetase syndrome.We retrospectively compared 212 muscle biopsies from antisynthetase syndrome patients regarding four pathology domains and histology of interests using t test and Fisher’s exact test as appropriate. We further compared the myofiber HLA-DR expression pattern in antisynthetase syndrome with 602 muscle biopsies with other autoimmune myositis and 140 muscle biopsies with other myopathies potentially containing myositis-like pathology and calculated sensitivity, specificity, positive predictive value, and negative predictive value to identify the most diagnostic pattern for antisynthetase syndrome.The most common myopathological pattern in antisynthetase syndrome was necrotizing myopathy (46.2%). Perifascular necrosis was present in 28.3% of antisynthetase syndrome. Anti-OJ and anti-EJ antisynthetase syndrome were associated with high muscle fiber scores. Anti-OJ also showed high inflammatory domain score. If muscle biopsies suspicious for dermatomyositis by sarcoplasmic myxovirus resistance protein A immunohistochemical expression and those with inclusion body myositis clinicopathology were excluded, myofiber HLA-DR expression was the most diagnostic of antisynthetase syndrome with 95.4% specificity, 61.2% sensitivity, 85.9% positive predictive value, and 84.2% negative predictive value. HLA-DR expression in perifascicular fibers was highly specific to anti-Jo-1 antisynthetase syndrome.Anti-OJ antisynthetase syndrome has more prominent myopathology than the other antisynthetase syndrome subtypes. Presence of myofiber HLA-DR expression in a clinicopathologically approved non-dermatomyositis and non-inclusion body myositis muscle biopsy is highly indicative of antisynthetase syndrome. Presence of HLA-DR expression suggests the involvement of type II interferon in the pathogenesis in antisynthetase syndrome subpopulation although the detailed mechanism and the reason for preferential perifascicular localization are yet to be identified.

A line blotting assay (LB) is currently used to detect myositis-specific autoantibodies (MSAs) in patients with idiopathic inflammatory myopathies (IIMs), because of its simplicity; however, the sensitivity and specificity of this assay is low. The aim of this study is to evaluate the accuracy of the commercial LB in detection of antinuclear matrix protein 2 (NXP2) antibody. Seventy-seven serum samples from patients with IIMs, in which anti-NXP2 antibodies were detected through immunoprecipitation and western blotting (IP-WB) using K562 cell lysate, were enrolled. All samples were assessed by LB and IP-WB using recombinant human NXP2 whole protein (rNXP2) produced by insect cells, and the positive rates of each assay were compared. Thirty-two samples (41.6%) showed false-negativity by LB, which includes 11 samples with negative results by IP-WB using rNXP2. Relative intensities of IP-WB using cell lysate were significantly higher in the samples with positive results by both LB and IP-WB using rNXP2, compared to samples with positive by IP-WB using rNXP2 but negative by LB. Three of 11 samples with negative results by both LB and IP-WB using rNXP2 revealed high antibody titers. Further, differences in post-transcriptional SUMOylation were observed between recombinant and natural NXP2 proteins. In conclusion, the LB showed low sensitivity for detection of anti-NXP2 antibody, an effect exacerbated at low titers of anti-NXP2 antibodies. Moreover, there appears to be differences in the reactivities of antibodies to recombinant and natural NXP2 proteins with different post-transcriptional modifications.

Background and ObjectivesDiscoveries of dermatomyositis-specific antibodies (DMSAs) in patients with dermatomyositis raised awareness of various myopathologic features among antibody subtypes. However, only perifascicular atrophy and perifascicular myxovirus resistant protein A (MxA) overexpression were officially included as definitive pathologic criteria for dermatomyositis classification. We aimed to demonstrate myopathologic features in MxA-positive dermatomyositis to determine characteristic myopathologic features in different DMSA subtypes.MethodsWe performed a retrospective pathology review of muscle biopsies of patients with dermatomyositis diagnosed between January 2009 and December 2020 in a tertiary laboratory for muscle diseases. We included all muscle biopsies with sarcoplasmic expression for MxA and seropositivity for DMSAs. MxA-positive muscle biopsies that tested negative for all DMSAs were included as seronegative dermatomyositis. We evaluated histologic features stratified according to 4 pathology domains (muscle fiber, inflammatory, vascular, and connective tissue) and histologic features of interest by histochemistry, enzyme histochemistry, and immunohistochemical study commonly used in the diagnosis of inflammatory myopathy. We performed ultrastructural studies of 54 available specimens.ResultsA total of 256 patients were included. Of these, 249 patients were positive for 1 of the 5 DMSAs (seropositive patients: 87 anti–transcription intermediary factor 1-γ [TIF1-γ], 40 anti–complex nucleosome remodeling histone deacetylase [Mi-2], 29 anti–melanoma differentiation gene 5 [MDA5], 83 anti–nuclear matrix protein 2 [NXP-2], and 10 anti–small ubiquitin-like modifier-activating enzyme [SAE] dermatomyositis) and 7 patients were negative for all 5 DMSAs (seronegative patients). Characteristic myopathologic features in each DMSA subtype were as follows: anti-TIF1-γ with vacuolated/punched out fibers (64.7%; p < 0.001) and perifascicular enhancement in HLA-ABC stain (75.9%; p < 0.001); anti-Mi-2 with prominent muscle fiber damage (score 4.9 ± 2.1; p < 0.001), inflammatory cell infiltration (score 8.0 ± 3.0; p = 0.002), perifascicular atrophy (67.5%; p = 0.02), perifascicular necrosis (52.5%; p < 0.001), increased perimysial alkaline phosphatase activity (70.0%; p < 0.001), central necrotic peripheral regenerating fibers (45.0%; p = 0.002), and sarcolemmal membrane attack complex deposition (67.5%; p < 0.001); anti-MDA5 with scattered/diffuse staining pattern of MxA (65.5%; p < 0.001) with less muscle pathology and inflammatory features; anti-NXP-2 with microinfarction (26.5%; p < 0.001); and anti-SAE and seronegative dermatomyositis with HLA-DR expression (50.0%; p = 0.02 and 57.1%; p = 0.02, respectively).DiscussionWe describe a comprehensive serologic–pathologic correlation of dermatomyositis primarily using MxA expression as an inclusion criterion. In our study, DMSAs were associated with distinctive myopathologic features suggesting different underlying pathobiologic mechanisms in each subtype.

This review summarizes and comments on current knowledge in dermatomyositis.The 2018 European Neuromuscular Centre classification of dermatomyositis has been challenging by the discovery of clinicopathological features associated with dermatomyositis-specific antibody (DMSA) that were not incorporated in the original criteria. These features include but may not be limited to the presence of perifascicular necrosis in anti-Mi-2 dermatomyositis; presence of diffuse nonperifascicular sarcoplasmic myxovirus resistance protein A expression in anti-MDA5 dermatomyositis; and dermatomyositis sine dermatitis in anti-NXP-2 dermatomyositis. Variations and subclassifications within the same DMSA subtypes are observed: anti-MDA5 dermatomyositis is clinically subcategorized into good, intermediate, and poor prognostic subgroups; concurrent anti-CCAR1 and anti-TIF1-γ positivity identify anti-TIF1-γ-positive patient with a lower risk for cancer-associated myositis. Owing to distinct IFN1-signaling pathway activation in dermatomyositis, JAK-STAT inhibitor - the pathway-targeted therapy, have been studied with promising results in refractory dermatomyositis and some new-onset dermatomyositis. In addition, the potential serum biomarkers for IFN1 pathway activation are being investigated for their performance in monitoring the disease activity and the efficacy of the treatment.DMSA, evidence of prominent IFN1 pathway activation, and risk/severity-associated biomarkers would likely play major roles in future dermatomyositis classification, disease monitoring, and treatment decision.

ObjectiveTo identify the characteristic pathologic features of dermatomyositis (DM) associated with anti-Mi-2 autoantibodies (anti-Mi-2 DM).MethodsWe reviewed 188 muscle biopsies from patients (1) pathologically diagnosed with DM through the sarcoplasmic expression for the myxovirus-resistant protein A and (2) serologically positive for 1 of 5 DM-specific autoantibodies (DMSAs) (anti-Mi-2, n = 30; other DMSAs, n = 152) or negative for all 5 DMSAs (n = 6). We then compared the histopathologic and immunohistochemical features of patients with anti-Mi-2 DM to those with non-Mi-2 DM and patients with anti-synthetase syndrome (ASS) (n = 212) using thettest, Fisher exact test, and a logistic regression model.ResultsPatients with anti-Mi-2 DM showed significantly higher severity scores in muscle fiber and inflammatory domains than non-Mi-2 DM patients. The presence of perifascicular necrosis, increased perimysial alkaline phosphatase activity, and sarcolemmal membrane attack complex deposition was more frequent in patients with anti-Mi-2 DM (p< 0.01). After Bonferroni correction, there were no significant differences in the percentages of the features mentioned above between the patients with anti-Mi-2 DM and those with ASS (p> 0.01).ConclusionPerifascicular necrosis and perimysial pathology, features previously reported in ASS, are common in patients with anti-Mi-2 DM. Our findings not only assist in differentiating anti-Mi-2 DM from other DM subtypes but also suggest the possibility of an overlapping mechanism between anti-Mi-2 DM and ASS.Classification of EvidenceThis study provides Class II evidence that the muscle biopsies of DM patients with anti-Mi-2 autoantibodies are more likely to demonstrate higher severity scores in muscle fiber and inflammatory domains.

Purpose of review Discoveries of myositis-specific antibodies, transcriptomic signatures, and clinicoseropathological correlation support classification of idiopathic inflammatory myopathies (IIM) into four major subgroups: dermatomyositis, immune-mediated necrotizing myopathy (IMNM), antisynthetase syndrome (ASS), and inclusion body myositis (IBM) whereas leaving polymyositis as a historical nonspecific diagnosis of exclusion. This review summarizes and comments on recent knowledge regarding the major subgroup of IIM. Recent findings Type 1 interferon (IFN1) pathway activation is the most prominent in dermatomyositis whereas type 2 interferon (IFN2) pathway activation is high in IBM and ASS; neither pathway is distinct in IMNM. Myxovirus-resistant protein A, IFN1 surrogate marker, is now one of definite dermatomyositis muscle biopsy criteria in the new 2018 European Neuromuscular Centre classification of dermatomyositis; the classification emphasizes on different categorization with and without dermatomyositis-specific antibody result. Novel HLA loci associated with anti-TIF1-γ, anti-Mi-2, and anti-Jo-1 antibodies in Caucasian population are identified. Associations of chaperon-assisted selective autophagy (CASA) and complement-mediated autoimmunity in IMNM as well as highly differentiated T cells in IBM are discovered. Summary Current IIM classification requires integrated clinicoseropathological approaches. Additional information, such as transcriptomics, HLA haplotyping, and potential biomarkers help tailoring categorization that may have future diagnostic and therapeutic implications.

ImportanceCurrent pathological criteria of dermatomyositis (DM) do not recognize different features among DM subtypes classified by dermatomyositis-specific antibodies (DMSAs).ObjectiveTo determine whether myopathological features differ among DM subtypes classified by DMSAs and whether the pathological features can be characterized by serologically defined DM subtype.DesignRetrospective review of muscle pathology slides of 256 patients diagnosed with DM from January 2009 to December 2020.SettingSingle center study in a tertiary laboratory for muscle diseases.ParticipantsA total of 256 patients whose DM diagnosis was pathologically confirmed based on the sarcoplasmic expression of myxovirus resistant protein A (MxA) were included. Of these, 249 patients were positive for one of the 5 DMSAs (seropositive patients, anti-TIF1-γ=87, anti-Mi-2=40, anti-MDA5=29, anti-NXP-2=83, and anti-SAE=10), and 7 were negative for all 5 DMSAs (seronegative patients).ExposureHistochemical, enzyme histochemical, immunohistochemical staining, and ultrastructural study.Main outcomes and measuresHistological features stratified according to four pathology domains: muscle fiber, inflammatory, vascular, and connective tissue domains, and histological features of interest by histochemistry, enzyme histochemistry, and immunohistochemical study commonly used in the diagnosis of inflammatory myopathy.ResultsDMSAs significantly associated with characteristic histochemical and immunohistochemical features were as follows: anti-TIF1-γ with vacuolated/punched out fibers (64.7%, PPPP=.002), perifascicular atrophy (67.5%, P=.02), perifascicular necrosis (52.5%, PPPPPPP=.02 and 57.1%, P=.02 respectively).Conclusion and relevanceWe described an extensive study on serological-pathological correlation of DM primarily using MxA expression as an inclusion criterion. DMSAs was associated with distinctive myopathological features in our studied cohort, suggesting that different pathobiological mechanisms may underscore each subtype.Key pointsQuestionAre myopathological features different among dermatomyositis (DM) subtypes classified by DM-specific autoantibodies (DMSAs)? If so what are the characteristic features of each subtype?FindingsThis study enrolled 256 (249 DMSA-positive and 7 seronegative) patients whose DM diagnosis was made pathologically by confirming the expression of myxovirus resistant protein A in the sarcoplasm of muscle fibers in muscle biopsy samples. The DM subtypes classified by the positive DMSAs were associated with distinctively characteristic pathological features.MeaningDifferent pathological features suggest different pathological mechanisms may well underly each DM subtype classified by DMSA.

Orbital cavernous venous malformations (CVMs) are usually slow progressing. Multiple CVMs, bilateral orbital CVMs, and acute presentations are rare. We present a rare, bilateral, orbital CVM with acute painful visual loss in the left eye. The initial clinical presentation mimicked an idiopathic orbital inflammation. Orbital magnetic resonance imaging revealed its rare location at the left orbital apex. Finally, pathology confirmed the presence of an intralesional hemorrhage of a CVM.

Idiopathic inflammatory myopathies (IIM) are rare diseases with heterogenous clinicopathological features. In recent years, new classification systems considering various combinations of clinical, serological, and pathological information have been proposed. This review summarizes recent clinicoseropathological development in major subgroups of IIM.Considering clinicoseropathological features, IIM are suggestively classified into four major subgroups: dermatomyositis, immune-mediated necrotizing myopathy (IMNM), antisynthetase syndrome (ASS), and inclusion body myositis (IBM). Many historically diagnosed polymyositis have been mainly reclassified as IBM, IMNM, and ASS. Different types of myositis-specific antibodies (MSA) suggest distinct clinicopathological subsets of IIM. Excluding IBM, at least one-third of the IIMs have no known associated MSA.MSA are crucial for IIM classification but can be negative. Thus, IIM should be universally classified using stepwise or integrated information on clinical, serological, and pathological findings.

Histopathologic evaluation of muscle biopsy samples is essential for classifying and diagnosing muscle diseases. However, the numbers of experienced specialists and pathologists are limited. Although new technologies such as artificial intelligence are expected to improve medical reach, their use with rare diseases, such as muscle diseases, is challenging because of the limited availability of training datasets. To address this gap, we developed an algorithm based on deep convolutional neural networks (CNNs) and collected 4041 microscopic images of 1400 hematoxylin-and-eosin-stained pathology slides stored in the National Center of Neurology and Psychiatry for training CNNs. Our trained algorithm differentiated idiopathic inflammatory myopathies (mostly treatable) from hereditary muscle diseases (mostly non-treatable) with an area under the curve (AUC) of 0.996 and achieved better sensitivity and specificity than the diagnoses done by nine physicians under limited diseases and conditions. Furthermore, it successfully and accurately classified four subtypes of the idiopathic inflammatory myopathies with an average AUC of 0.958 and classified seven subtypes of hereditary muscle disease with an average AUC of 0.936. We also established a method to validate the similarity between the predictions made by the algorithm and the seven physicians using visualization technology and clarified the validity of the predictions. These results support the reliability of the algorithm and suggest that our algorithm has the potential to be used straightforwardly in a clinical setting. The authors developed a deep convolutional neural network-based algorithm to support pathological muscle diagnosis. The algorithm differentiated idiopathic inflammatory myopathies and outperformed nine human physicians under limited diseases and conditions. These results suggest that the algorithm has the potential to be used directly in clinical settings.

Sporadic late‐onset nemaline myopathy (SLONM) is a rare adult‐onset non‐hereditary disease with subacute proximal muscle and often axial muscle weakness, characterized by the presence of nemaline bodies in skeletal muscle biopsies. Considering its association with concurrent monoclonal gammopathy of undetermined significance (MGUS), the disease is classified into two major subtypes (1) SLONM without MGUS (SLONM‐noMGUS) and (2) with MGUS (SLONM‐MGUS) association. SLONM associated with HIV infection (SLONM‐HIV) is also reported. SLONM‐MGUS has been shown to be associated with poorer prognosis and required aggressive treatment including high‐dose melphalan and autologous stem cell transplantation. The approach is currently debatable as recent reports suggested effectiveness of intravenous immunoglobulin as initial treatment with indifference of overall survival despite the presence of MGUS. Our study aimed to find an underlying basis by review of pathological features in 49 muscle biopsy proven‐SLONM from two large tertiary centers in Japan and Germany (n = 49: SLONM‐noMGUS = 34, SLONM‐MGUS = 13, SLONM‐HIV = 2). We compared pathological findings in SLONM‐noMGUS and SLONM‐MGUS and focused on the presence of any detectable inflammatory features by immunohistochemistry. The clinical and histological features in SLONM‐noMGUS and SLONM‐MGUS were not distinctively different except for more common regenerating fibers (>5% of myofibers) present in SLONM‐MGUS (p, Retroactive myopathological study of 49 SLONM highlights common immunopathological elements among SLONM‐MGUS and SLONM‐noMGUS. CD68+ cells were the most common inflammatory cells observed in SLONM.

Objectives Myositis-specific autoantibodies (MSAs) define distinct clinical subsets of idiopathic inflammatory myopathies (IIMs). The anti-nuclear matrix protein 2 (NXP2) antibody, a MSA detected in juvenile/adult IIMs, has been reported to be associated with a high risk of subcutaneous calcinosis, subcutaneous oedema and internal malignancies. The study aimed to clarify the clinical features of anti-NXP2 antibody-positive IIMs in detail. Methods This was a multicentre retrospective observational study on 76 anti-NXP2 antibody-positive patients. The antibody was detected via a serological assay using immunoprecipitation and western blotting. The patients were selected from 162 consecutive Japanese patients with IIMs. Results The cohort of anti-NXP2 antibody-positive IIMs included 29 juvenile patients and 47 adult patients. Twenty-seven (35.5%) patients presented with polymyositis phenotype without dermatomyositis-specific skin manifestations (heliotrope rash or Gottron sign/papules); this was more common in the adults than children (48.9% vs 15.8%, P Conclusion Anti-NXP2 antibody-positive IIMs, which include dermatomyositis sine dermatitis, are characterized by atypical skin manifestations and extensive muscular involvement.

ObjectiveMyositis-specific autoantibodies (MSAs) define distinct clinical subsets of idiopathic inflammatory myopathies (IIMs). The anti-nuclear matrix protein 2 (NXP2) antibody, a MSA detected in juvenile/adult IIMs, has been reported to be associated with a high risk of subcutaneous calcinosis, subcutaneous edema, and internal malignancies. The study aimed to clarify the clinical features of anti-NXP2 antibody-positive IIMs in detail.MethodsThis multi-center retrospective observational study on 76 anti-NXP2 antibody-positive patients. The antibody was detected via a serological assay using immunoprecipitation and western blotting. The patients were selected from 162 consecutive Japanese patients with IIMs.ResultsThe cohort of anti-NXP2 antibody-positive IIMs included 29 juvenile patients and 47 adult patients. Twenty-seven (35.5%) patients presented with polymyositis phenotype without dermatomyositis-specific skin manifestations (heliotrope rash and Gottron sign/papules); this was more common in the adults than children (48.9% vs. 15.8%, P < 0.01). Nine (11.8%) patients had subcutaneous calcinosis, and 20 (26.3%) patients had subcutaneous edema. In addition, the proportion of patients with muscle weakness extending to the distal limbs was high (36 patients [47.4%]) in this cohort. Adult patients had a higher prevalence of malignancy than the general population (age-standardized incidence ratio of malignancies: 22.4).ConclusionAnti-NXP2 antibody-positive IIMs, which include dermatomyositis sine dermatitis, are characterized by atypical skin manifestations and extensive muscular involvement.

Abnormal gut motility is a feature of several mitochondrial encephalomyopathies, and mutations in genes such as TYMP and POLG, have been linked to these rare diseases. The human genome encodes three DNA ligases, of which only one, ligase III (LIG3), has a mitochondrial splice variant and is crucial for mitochondrial health. We investigated the effect of reduced LIG3 activity and resulting mitochondrial dysfunction in seven patients from three independent families, who showed the common occurrence of gut dysmotility and neurological manifestations reminiscent of mitochondrial neurogastrointestinal encephalomyopathy. DNA from these patients was subjected to whole exome sequencing. In all patients, compound heterozygous variants in a new disease gene, LIG3, were identified. All variants were predicted to have a damaging effect on the protein. The LIG3 gene encodes the only mitochondrial DNA (mtDNA) ligase and therefore plays a pivotal role in mtDNA repair and replication. In vitro assays in patient-derived cells showed a decrease in LIG3 protein levels and ligase activity. We demonstrated that the LIG3 gene defects affect mtDNA maintenance, leading to mtDNA depletion without the accumulation of multiple deletions as observed in other mitochondrial disorders. This mitochondrial dysfunction is likely to cause the phenotypes observed in these patients. The most prominent and consistent clinical signs were severe gut dysmotility and neurological abnormalities, including leukoencephalopathy, epilepsy, migraine, stroke-like episodes, and neurogenic bladder. A decrease in the number of myenteric neurons, and increased fibrosis and elastin levels were the most prominent changes in the gut. Cytochrome c oxidase (COX) deficient fibres in skeletal muscle were also observed. Disruption of lig3 in zebrafish reproduced the brain alterations and impaired gut transit in vivo. In conclusion, we identified variants in the LIG3 gene that result in a mitochondrial disease characterized by predominant gut dysmotility, encephalopathy, and neuromuscular abnormalities. Bonora et al. identify a new mitochondrial recessive disorder caused by biallelic variants in the LIG3 gene encoding DNA ligase III, which is responsible for mitochondrial DNA repair. Clinical signs include gut dysmotility and neurological features such as leucoencephalopathy, epilepsy and stroke-like episodes.

Histopathologic evaluation is essential for categorizing and studying neuromuscular disorders. However, experienced specialists and pathologists are limited, especially in underserved areas. Although new technologies, such as artificial intelligence, are expected to improve medical reach, their use in rare diseases is challenging because of the limited availability of training datasets. To address this knowledge gap, we developed an algorithm based on deep convolutional neural networks that used data from microscopic images of hematoxylin-and-eosin-stained pathology slides. Our algorithm differentiated idiopathic inflammatory myopathies (mostly treatable) from hereditary muscle diseases (mostly non-treatable) and achieved better sensitivity and specificity than real physicians' diagnoses. Furthermore, it successfully and accurately classified four subtypes of the abovementioned muscular conditions. These results suggest that our algorithm can be safely used in a clinical setting. We established the similarity between the algorithm's and physicians' predictions using visualization technology, and clarified the validity of the predictions.

IntroductionInclusion body myositis (IBM) is an idiopathic inflammatory myopathy, characterized by unique clinical features including finger flexor and quadriceps muscle weakness and a lack of any reliable treatment. The human leukocyte antigen (HLA)-DRB1 allele and autoantibody profiles in Japanese IBM patients have not been fully elucidated.MethodsWe studied 83 Japanese IBM patients with a mean age of 69 years (49 males and 34 females) who participated in the 'Integrated Diagnosis Project for Inflammatory Myopathies' from January 2011 to September 2016. IBM was diagnosed by histological diagnosis. Various autoantibodies were screened by RNA immunoprecipitation and enzyme-linked immunosorbent assays. HLA-DRB1 genotyping was performed using polymerase chain reaction-sequence based typing. A total of 460 unrelated healthy Japanese controls were also studied.ResultsThe allele frequencies of DRB1*01:01, DRB1*04:10, and DRB1*15:02 were significantly higher in the IBM group than in the healthy control group (Corrected P = 0.00078, 0.00038 and 0.0046). There was a weak association between the DRB1*01:01 allele and severe leg muscle weakness and muscle atrophy. While hepatitis type C virus infection and autoantibodies to cytosolic 5'-nucleotidase 1A were found in 18 and 28 patients, respectively, no significant association with HLA-DRB1 alleles was observed.ConclusionJapanese IBM patients had the specific HLA-DRB1 allele and autoantibody profiles.

The myosin-directed chaperone UNC-45B is essential for sarcomeric organization and muscle function from Caenorhabditis elegans to humans. The pathological impact of UNC-45B in muscle disease remained elusive. We report ten individuals with bi-allelic variants in UNC45B who exhibit childhood-onset progressive muscle weakness. We identified a common UNC45B variant that acts as a complex hypomorph splice variant. Purified UNC-45B mutants showed changes in folding and solubility. In situ localization studies further demonstrated reduced expression of mutant UNC-45B in muscle combined with abnormal localization away from the A-band towards the Z-disk of the sarcomere. The physiological relevance of these observations was investigated in C. elegans by transgenic expression of conserved UNC-45 missense variants, which showed impaired myosin binding for one and defective muscle function for three. Together, our results demonstrate that UNC-45B impairment manifests as a chaperonopathy with progressive muscle pathology, which discovers the previously unknown conserved role of UNC-45B in myofibrillar organization.

Background Muscle biopsy facilitates morphologic, biochemical, and ultrastructural analysis of muscle for the purpose of making definitive neuromuscular diagnosis. However, muscle biopsy is an expensive, invasive, time-consuming, and resource-dependent procedure. The need for general anesthesia in children also increases the risks associated with this procedure. The aim of this study was to investigate the benefits of muscle biopsies performed over a 10-year period, with a focus on indications, suspected and histopathologic diagnosis, and impact on diagnosis and management decisions. Methods We retrospectively reviewed results of muscle biopsies performed in children at our center during the 2004 to 2014 study period. Clinical presentations, biopsy complications, pathologic results, and changes in management decision were reviewed and analyzed. Results Biopsies from 92 patients were included. Mean age of patients was 7.1years, and 66.3% were male. There were no perioperative complications, and definitive diagnosis was made in 74 patients. Regardless of whether pathologic changes were found or not, information gained from muscle biopsy significantly impacted prognosis and subsequent genetic counseling. Conclusions Muscle biopsy is a safe and useful diagnostic tool in children suspected of having neuromuscular diseases, especially in those with muscle diseases. Definitive pathologic diagnosis helps to optimize treatment, counseling, and surveillance. The type of study and level of evidence Study of diagnostic test: level 1.

The most recent WHO classification (2016) for gliomas introduced integrated diagnoses requiring both phenotypic and genotypic data. This approach presents difficulties for countries with limited resources for laboratory testing. The present study describes a series of 118 adult Thai patients with diffuse gliomas, classified by the WHO 2016 classification. The purpose was to demonstrate how a diagnosis can still be achieved using a simplified approach that combines clinical, morphological, immunohistochemical, and fewer molecular assays than typically performed. This algorithm starts with tumor location (midline vs. non-midline) with diffuse midline glioma identified by H3 K27M immunostaining. All other tumors are placed into one of 6 categories, based on morphologic features rather than specific diagnoses. Molecular testing is limited to IDH1/IDH2 mutations, plus co-deletion of 1p/19q for cases with oligodendroglial features and TERT promoter mutation for cases without such features. Additional testing for co-deletion of 1p/19q, TERT promoter mutation and BRAF mutations are only used in selected cases to refine diagnosis and prognosis. With this approach, we were able to reach the integrated diagnosis in 117/118 cases, saving 50 % of the costs of a more inclusive testing panel. The demographic data and tumor subtypes were found to be similar to series from other regions of the world. To the best of our knowledge, this is to the first reported series of diffuse gliomas in South-East Asia categorized by the WHO 2016 classification system.

Background: Sarcomas are rare and heterogeneous cancers. We assessed the contribution of DICER1 mutations to sarcoma development. Methods: The coding region of DICER1 was sequenced in 67 sarcomas using a custom Fluidigm Access Array. The RNase III domains were Sanger sequenced in six additional sarcomas to identify hotspot DICER1 variants. Results: The median age of sarcoma diagnosis was 45.7 years (range: 3 months to 87.4 years). A recurrent embryonal rhabdomyosarcoma (ERMS) of the broad ligament, first diagnosed at age 23 years, harboured biallelic pathogenic somatic DICER1 variants (1 truncating and 1 RNase IIIb missense). We identified nine other DICER1 variants. One somatic variant (p.L1070V) identified in a pleomorphic sarcoma and one germline variant (c.2257-7A>G) may be pathogenic, but the others are considered to be benign. Conclusions: We show that deleterious DICER1 mutations underlie the genetic basis of only a small fraction of sarcomas, in particular ERMS of the urogenital tract.

To investigate the clinical characteristics, laboratory features, and treatment outcomes of Thai patients compared between those with necrotizing autoimmune myopathy (NAM) and those with other idiopathic inflammatory myopathies (IIMs) or non-NAM.This multicenter case-control study included patients aged ≥ 18 years who were diagnosed with IIMs by muscle pathology, and who had relevant clinical and laboratory data, including muscle enzymes, from at least 3 follow-up visits during a 1-year period. Baseline clinical and laboratory data were recorded. Serum myositis-specific autoantibodies (MSAs) were obtained on the date of recruitment.Of the 70 included patients, 67% had NAM, and 33% had non-NAM. The mean age of patients was 50.5 ± 15.9 years, 67% were female, and the median duration of symptoms was 2 months (IQR, 1-4). History of cancer was significantly higher in non-NAM (21.7% vs. 2.1%, p = 0.01). Gottron's papules were significantly more prevalent in non-NAM (21.7% vs. 4.3%, p = 0.04). Non-NAM had a higher prevalence of anti-Mi-2a (17.4% vs. 2.1%, p = 0.04) and Mi-2b (17.4% vs. 0.0%, p = 0.01); however, the presence of other MSAs, including anti-HMGCR and anti-SRP, was similar between groups. Improvement in motor power and treatment intensification with glucocorticoid and/or immunosuppressive agents 3 times throughout the follow-up period was similar between groups (NAM 46.8% vs. non-NAM 34.8%, p = 0.34).NAM is indistinguishable from non-NAM by clinical manifestations, serology, or laboratory findings, except that pathognomonic skin sign of Gottron's papules and anti-Mi2 are suggestive of dermatomyositis. The integration of clinical, serological, and pathological data is essential for making a diagnosis of NAM.Key Points• NAM is indistinguishable from non-NAM by clinical manifestations, serology, or laboratory findings.• The integration of clinical, serological, and pathological data is essential for making a diagnosis of NAM.

COL4A1-related disorder is recognized as a systemic disease because the alpha 1 chain of type IV collagen, encoded by COL4A1, is essential for basement membrane stability. However, muscular manifestations related to this disorder are rarely reported. We report the case of a 2-year-old boy with porencephaly, who harbored a de novo COL4A1 mutation of c.1853G > A, p. (Gly618Glu) and exhibited recurrent rhabdomyolysis with viral or bacterial infections. Moreover, he developed obstructive hypertrophic cardiomyopathy which required surgical intervention. Skeletal muscle biopsy revealed findings compatible with fiber-type disproportion. Ultrastructural study demonstrated the similar findings previously reported in mice with Col4a1 mutation including collagen disarray and reduction of electron density in the basement membrane of capillary endothelial cells and muscle fibers. Dilated endoplasmic reticulum in the capillary endothelial cells is also noted. This report adds another disease spectrum of COL4A1 mutation which include porencephaly, hypertrophic cardiomyopathy, rhabdomyolysis and fiber-type disproportion.

IMPORTANCE: Reports on dermatomyositis (DM) sine dermatitis (DMSD) are scarce, and the concept of the disease has not been widely accepted. OBJECTIVE: To confirm the existence of DMSD, determine its prevalence, and characterize its serologic features. DESIGN, SETTING, AND PARTICIPANTS: This is a cohort study that reviewed clinical information, laboratory data, and muscle pathology slides from January 2009 to August 2019. We further assessed the follow-up data of 14 patients with DMSD. The median (interquartile range) follow-up period was 34 (16-64) months. Muscle biopsy samples, along with clinical information and laboratory data, were sent to a referral center for muscle diseases in Japan for diagnosis. Of patients whose myopathologic diagnosis was made at the National Center of Neurology and Psychiatry between January 2009 and August 2019, 199 patients were eligible for inclusion. These patients underwent full investigation for DM-specific autoantibodies (against transcriptional intermediary factor γ, Mi-2, melanoma differentiation–associated gene 5, nuclear matrix protein 2 [NXP-2], and small ubiquitin-like modifier activating enzyme ); however, 17 patients were excluded because their muscle fibers did not express myxovirus resistance protein A, a sensitive and specific marker of DM muscle pathology. MAIN OUTCOMES AND MEASURES: Diagnosis of DMSD was based on the absence of a skin rash at the time of muscle biopsy. RESULTS: Of the 182 patients, 93 were women (51%) and 46 were children (25%) (

Sporadic late-onset nemaline myopathy with monoclonal gammopathy of undetermined significance is a rare subacute adult-onset myopathy. Without appropriate treatment, the prognosis is unfavorable and can be fatal. Various efficacious treatment options have been reported. High dose melphalan followed by autologous stem cell transplantation is the most used option with favorable outcome. Nevertheless, potentially safer alternative regimens await exploration. Here, we report the case of sporadic late-onset nemaline myopathy with monoclonal gammopathy of undetermined significance in a 33-year-old man with significant clinical improvement and complete remission of monoclonal gammopathy after 5 cycles of cyclophosphamide, thalidomide, and dexamethasone regimen. The regimen may be considered as an alternative option for patients with sporadic late-onset nemaline myopathy with monoclonal gammopathy of undetermined significance that are ineligible for upfront high-dose melphalan with autologous stem cell transplantation or that are being treated in resource-limited settings. Longer-term follow-up is needed to determine the long-term effectiveness of the cyclophosphamide, thalidomide, and dexamethasone regimen.

Although targeted therapies are often effective systemically, they fail to adequately control brain metastases. In preclinical models of breast cancer that faithfully recapitulate the disparate clinical responses in these micro-environments, we observed that brain metastases evade phosphatidylinositide 3-kinase (PI3K) inhibition despite drug accumulation in the brain lesions. In comparison to extracranial disease, we observed increased HER3 expression and phosphorylation in brain lesions. HER3 blockade overcame the resistance of HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases to PI3K inhibitors, resulting in marked tumor growth delay and improvement in mouse survival. These data provide a mechanistic basis for therapeutic resistance in the brain microenvironment and identify translatable treatment strategies for HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases.

Melanocytic matricoma is a rare cutaneous adnexal tumor occurring in humans with only 13 cases reported in the literature. The typical lesion is a circumscribed pigmented nodule on sun-damaged skin. Most cases have occurred in elderly men. The tumor contains a mixed population of matrical cells, supramatrical cells, shadow or ghost cells, and dendritic melanocytes. We report two cases of melanocytic matricoma in two elderly women with unusual histopathological features such as cystic degeneration and focal granulomatous inflammation, which are considered to be atypical for this entity.

Primary leiomyosarcoma of the thyroid gland is uncommon. To date, 20 cases have been reported in English in the literature. The tumors usually present in elderly patients with female predilection and are associated with poor clinical outcome. Herein, we report an additional case of primary thyroid leiomyosarcoma in a 64-year-old woman. She underwent total thyroidectomy and later was discovered to have multiple lung and liver metastases. The patient died 3 months after surgery. The major differential diagnoses including undifferentiated (anaplastic) carcinoma of the thyroid, spindle cell variant of medullary thyroid carcinoma, spindle cell tumor with thymus-like differentiation, uncommon primary tumor of the thyroid and metastatic tumors with predominant spindle cells are discussed.

Signet-ring cell/histiocytoid carcinomas of the eyelid are rare, slow-growing, and locally aggressive tumors. They predominantly affect elderly men and clinically resemble chronic inflammatory process such as blepharitis and chalazion. To date, the histogenesis of the tumors is still controversial. Only 27 cases of primary signet-ring cell/histiocytoid carcinomas of the eyelid are published in the literature. Local recurrence and distant metastasis occur in 8 and 7 cases, respectively. We report clinical, radiographic, and pathological features of a case of signet-ring cell/histiocytoid carcinoma of the eyelid with review of relevant literature.

Progression of anaplastic glioma (World Health Organization [WHO] grade III) is typically determined radiographically, and transformation to glioblastoma (GB) (WHO grade IV) is often presumed at that time. However, the frequency of actual histopathologic transformation of anaplastic glioma and the subsequent clinical impact is unclear. To determine these associations, we retrospectively reviewed all anaplastic glioma patients who underwent surgery at our center at first radiographic progression, and we examined the effects of histological diagnosis, clinical history, and molecular factors on transformation rate and survival. We identified 85 anaplastic glioma (39 astrocytoma, 24 oligodendroglioma, 22 oligoastrocytoma), of which 38.8% transformed to GB. Transformation was associated with shorter overall survival (OS) from the time of diagnosis (3.4 vs. 10.9 years, p = 0.0005) and second surgery (1.0 vs. 3.5 years, p < 0.0001). Original histologic subtype did not significantly impact the risk of transformation or OS. No other factors, including surgery, adjuvant therapy or molecular markers, significantly affected the risk of transformation. However, mutations in isocitrate dehydrogenase 1 (IDH1) was associated with longer time to progression (median 4.6 vs. 1.4 years, p = 0.008) and OS (median 10.0 vs. 4.2 years, p = 0.046). At radiographic progression, tissue diagnosis may be warranted as histologic grade may provide valuable prognostic information and affect therapeutic clinical trial selection criteria for this patient population.

A number of key mutations that affect treatment and prognosis have been identified in human gliomas. Two major ways to identify these mutations in a tumor sample are direct interrogation of the mutated DNA itself and immunohistochemistry to assess the effects of the mutated genes on proteins. Immunohistochemistry is an affordable, robust, and widely available technology that has been in place for decades. For this reason, the use of immunohistochemical approaches to assess molecular genetic changes has become an essential component of state-of-the-art practice. In contrast, even though DNA sequencing technologies are undergoing rapid development, many medical centers do not have access to such methodologies and may be thwarted by the relatively high costs of sending out such tests to reference laboratories. This review summarizes the current experience using immunohistochemistry of glioma samples to identify mutations in IDH1, TP53, ATRX, histone H3 genes, BRAF, EGFR, MGMT, CIC, and FUBP1 as well as guidelines for prudent use of DNA sequencing as a supplemental method.

The occurrence of Ewing sarcoma-peripheral primitive neuroectodermal tumor as a primary intracranial tumor is very rare, with only 29 cases reported in the literature, 19 of which have included molecular studies. We present the clinical, radiologic and pathologic findings of an intracranial Ewing sarcoma in a 22-year-old woman arising from the dura over the right frontal convexity. The patient underwent craniotomy with gross total excision of the tumor. The tumor showed atypical histology and the diagnosis was confirmed by detection of a rearrangement of the EWSR1 gene by fluorescent in situ hybridization and identification of the diagnostic t(11;22)(q24;q12) translocation by reverse transcription-polymerase chain reaction. Additional features were detected in this tumor that are known to be associated with an unfavorable prognosis, including loss of p16 expression and gains of chromosomes 1q and 12. The patient experienced the most rapid downhill course reported to date for intracranial Ewing sarcoma, developing multiple extracranial metastases at 2 months and dying 6 months after the initial operation.

Thepatientwasa14-year-oldThaiboywhopresentedatanorthopedic clinic with kyphoscoliosis first detected 1 yearprior to medical attention. He was the first child of non-consanguineous parents; the pregnancy and delivery wereuneventful.He had normal developmental milestones.Thepatient noticed easy fatigability after exercise which wors-ened during the past year. His younger brother was 10years old and healthy. There was no history ofneuromuscular disease in his family. His father passedaway due to an unrelated incident. General examinationrevealed a body weight of 30 kg and a height of 149 cm,bilateral ptosis, high-arched palate, kyphoscoliosis, andasymmetrical chest wall. Proximal muscle weakness ofgrade 4 by Medical Research Council Scale in all extrem-itiesandareflexiawerenoted.Themuscletonewasnormal.SerumCKwas49 IU/L.Echocardiogramshowedmildpul-monary and tricuspid regurgitation. Pulmonary functiontestsshowedrestrictivelungdisease;theforcedvitalcapac-ity was 1.56 L (51% of predicted). Sleep study revealedapnea-hypopnea index 13.6 per hour associated withsevere oxygen desaturation (minimum SpO

Brain metastases represent a devastating progression of luminal breast cancer. While targeted therapies are often effective systemically, they fail to adequately control brain metastases. In preclinical models that faithfully recapitulate the disparate clinical responses in these microenvironments, we observed that brain metastases evade PI3K inhibition despite efficient drug delivery. In comparison to extracranial disease, there is increased HER3 expression and phosphorylation in the brain lesions. HER3 blockade overcomes the resistance of both HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases to PI3K inhibitors, leading to striking tumor growth delay and significant improvement of mouse survival. Collectively, these data provide a mechanistic basis underlying therapeutic resistance in the brain microenvironment and identify rapidly translatable treatment strategiesfor HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases. Citation Format: Gino B. Ferraro, David P. Kodack, Vasileios Askoxylakis, Qing Sheng, Mark Badeaux, Shom Goel, Xiaolong Qi, Ram Shankaraiah, Alexander Z. Cao, Rakesh R. Ramjiawan, Divya Bezwada, Bhushankumar Patel, Youngchul Song, Carlotta Costa, Kamila Naxerova, Christina Wong, Jonas Kloepper, Rita Das, Angela Tam, Jantima Tanboon, Dan G. Duda, Ryan C. Miller, Marni B. Siegel, Carey K. Anders, Melinda Sanders, Valeria M. Estrada, Robert Schlegel, Carlos L. Arteaga, Elena Brachtel, Alan Huang, Dai Fukumura, Jeffrey A. Engelman, Rakesh K. Jain. The brain microenvironment mediates resistance in luminal breast cancer to PI3K inhibition through HER3 activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5008. doi:10.1158/1538-7445.AM2017-5008