Complement and MHC patterns can provide the diagnostic framework for inflammatory neuromuscular diseases.

Histopathological analysis stands as the gold standard for the identification and differentiation of inflammatory neuromuscular diseases. These disorders continue to constitute a diagnostic challenge due to their clinical heterogeneity, rarity and overlapping features. To establish standardized protocols for the diagnosis of inflammatory neuromuscular diseases, the development of cost-effective and widely applicable tools is crucial, especially in settings constrained by limited resources. The focus of this review is to emphasize the diagnostic value of major histocompatibility complex (MHC) and complement patterns in the immunohistochemical analysis of these diseases. We explore the immunological background of MHC and complement signatures that characterize inflammatory features, with a specific focus on idiopathic inflammatory myopathies. With this approach, we aim to provide a diagnostic algorithm that may improve and simplify the diagnostic workup based on a limited panel of stainings. Our approach acknowledges the current limitations in the field of inflammatory neuromuscular diseases, particularly the scarcity of large-scale, prospective studies that validate the diagnostic potential of these markers. Further efforts are needed to establish a consensus on the diagnostic protocol to effectively distinguish these diseases.

Multi-level profiling unravels mitochondrial dysfunction in myotonic dystrophy type 2.

Myotonic dystrophy type 2 (DM2) is an autosomal-dominant multisystemic disease with a core manifestation of proximal muscle weakness, muscle atrophy, myotonia, and myalgia. The disease-causing CCTG tetranucleotide expansion within the CNBP gene on chromosome 3 leads to an RNA-dominated spliceopathy, which is currently untreatable. Research exploring the pathophysiological mechanisms in myotonic dystrophy type 1 has resulted in new insights into disease mechanisms and identified mitochondrial dysfunction as a promising therapeutic target. It remains unclear whether similar mechanisms underlie DM2 and, if so, whether these might also serve as potential therapeutic targets. In this cross-sectional study, we studied DM2 skeletal muscle biopsy specimens on proteomic, molecular, and morphological, including ultrastructural levels in two separate patient cohorts consisting of 8 (explorative cohort) and 40 (confirmatory cohort) patients. Seven muscle biopsy specimens from four female and three male DM2 patients underwent proteomic analysis and respiratory chain enzymology. We performed bulk RNA sequencing, immunoblotting of respiratory chain complexes, mitochondrial DNA copy number determination, and long-range PCR (LR-PCR) to study mitochondrial DNA deletions on six biopsies. Proteomic and transcriptomic analyses revealed a downregulation of essential mitochondrial proteins and their respective RNA transcripts, namely of subunits of respiratory chain complexes I, III, and IV (e.g., mt-CO1, mt-ND1, mt-CYB, NDUFB6) and associated translation factors (TACO1). Light microscopy showed mitochondrial abnormalities (e.g., an age-inappropriate amount of COX-deficient fibers, subsarcolemmal accumulation) in most biopsy specimens. Electron microscopy revealed widespread ultrastructural mitochondrial abnormalities, including dysmorphic mitochondria with paracrystalline inclusions. Immunofluorescence studies with co-localization of autophagy (p62, LC-3) and mitochondrial marker proteins (TOM20, COX-IV), as well as immunohistochemistry for mitophagy marker BNIP3 indicated impaired mitophagic flux. Immunoblotting and LR-PCR did not reveal significant differences between patients and controls. In contrast, mtDNA copy number measurement showed a reduction of mtDNA copy numbers in the patient group compared to controls. This first multi-level study of DM2 unravels thus far undescribed functional and structural mitochondrial abnormalities. However, the molecular link between the tetranucleotide expansion and mitochondrial dysfunction needs to be further elucidated.

Methylation of the 4q35 D4Z4 repeat defines disease status in facioscapulohumeral muscular dystrophy.

Genetic diagnosis of facioscapulohumeral muscular dystrophy (FSHD) remains a challenge in clinical practice as it cannot be detected by standard sequencing methods despite being the third most common muscular dystrophy. The conventional diagnostic strategy addresses the known genetic parameters of FSHD: the required presence of a permissive haplotype, a size reduction of the D4Z4 repeat of chromosome 4q35 (defining FSHD1) or a pathogenic variant in an epigenetic suppressor gene (consistent with FSHD2). Incomplete penetrance and epistatic effects of the underlying genetic parameters as well as epigenetic parameters (D4Z4 methylation) pose challenges to diagnostic accuracy and hinder prediction of clinical severity. In order to circumvent the known limitations of conventional diagnostics and to complement genetic parameters with epigenetic ones, we developed and validated a multistage diagnostic workflow that consists of a haplotype analysis and a high-throughput methylation profile analysis (FSHD-MPA). FSHD-MPA determines the average global methylation level of the D4Z4 repeat array as well as the regional methylation of the most distal repeat unit by combining bisulphite conversion with next-generation sequencing and a bioinformatics pipeline and uses these as diagnostic parameters. We applied the diagnostic workflow to a cohort of 148 patients and compared the epigenetic parameters based on FSHD-MPA to genetic parameters of conventional genetic testing. In addition, we studied the correlation of repeat length and methylation level within the most distal repeat unit with age-corrected clinical severity and age at disease onset in FSHD patients. The results of our study show that FSHD-MPA is a powerful tool to accurately determine the epigenetic parameters of FSHD, allowing discrimination between FSHD patients and healthy individuals, while simultaneously distinguishing FSHD1 and FSHD2. The strong correlation between methylation level and clinical severity indicates that the methylation level determined by FSHD-MPA accounts for differences in disease severity among individuals with similar genetic parameters. Thus, our findings further confirm that epigenetic parameters rather than genetic parameters represent FSHD disease status and may serve as a valuable biomarker for disease status.

[Vasculitic involvement of the skeletal muscle and the peripheral nervous system: clinical and neuropathologic perspective]. / Vaskulitische Beteiligung der Skelettmuskulatur und des peripheren Nervensystems: Klinische und neuropathologische Perspektive.

The peripheral nervous system is a classic target organ in systemic vasculitis. In addition, the skeletal muscle can also be affected. Myalgia, muscle weakness and sensory deficits are typical signs, which can lead to severe functional limitations and impaired of quality of life. Vasculitic involvement of the skeletal muscle (vasculitic myopathy [VM]) and peripheral nerves (vasculitic neuropathy [VN]) occurs predominantly in polyarteritis nodosa and small-vessel vasculitis. VM presents with elevated markers of inflammation and is typically characterized by immobilizing myalgia with normal creatine kinase activity and diffuse or patchy areas of hyperintensity on T2-weighted MRI ("MRI myositis without myositis"). In VN, sensor motor deficits predominantly affect the lower extremity in the area supplied by several peripheral nerves (e.g., mononeuritis multiplex) with acute to subacute history. The histopathological examination of nerve and muscle biopsies is the gold standard for the diagnosis of vasculitic manifestations and has a significant impact on the therapeutic approach.

The current clinical perception of myotonic dystrophy type 2.

PURPOSE OF REVIEW: Myotonic dystrophy type 2 (DM2) is a genetic disorder belonging to the spectrum of myotonic dystrophies. DM2 is characterized by progressive muscle weakness, wasting and muscle pain (myalgia), but can also affect many other organ systems. In this review, we provide an updated overview on the research literature on DM2 with a focus on the management of multisystemic involvement and atypical clinical phenotypes. RECENT FINDINGS: Recent studies have focused on different aspects of multisystemic involvement. Early and severe cardiac involvement can occur in DM2 and needs to be managed appropriately. Diabetes has been shown to be more common in DM2 than in DM1, while a combination of symptoms (cataracts, myotonia, tremor) can be used to raise clinical suspicion and initiate genetic testing for DM2. Autoimmune disease has been shown to occur in up to one-third of DM2 patients, possibly due to altered immune pathways. New evidence also suggests a childhood-onset phenotype presenting with foot deformities. SUMMARY: The multisystemic aspects of the disease require a multidisciplinary approach for some patients, most likely even including state-of-the-art cardiac and brain imaging to detect and treat complications earlier. Of note, our concept of DM2 as an adult-onset disease is somewhat challenged by evidence suggesting a few pediatric DM2 patients and possibly anticipation, at least in some DM2 families. More studies, including larger cohorts, are needed to better understand this possible early-onset DM2 phenotype variant.

Senescent fibro-adipogenic progenitors are potential drivers of pathology in inclusion body myositis.

Inclusion body myositis (IBM) is unique across the spectrum of idiopathic inflammatory myopathies (IIM) due to its distinct clinical presentation and refractoriness to current treatment approaches. One explanation for this resistance may be the engagement of cell-autonomous mechanisms that sustain or promote disease progression of IBM independent of inflammatory activity. In this study, we focused on senescence of tissue-resident cells as potential driver of disease. For this purpose, we compared IBM patients to non-diseased controls and immune-mediated necrotizing myopathy patients. Histopathological analysis suggested that cellular senescence is a prominent feature of IBM, primarily affecting non-myogenic cells. In-depth analysis by single nuclei RNA sequencing allowed for the deconvolution and study of muscle-resident cell populations. Among these, we identified a specific cluster of fibro-adipogenic progenitors (FAPs) that demonstrated key hallmarks of senescence, including a pro-inflammatory secretome, expression of p21, increased ß-galactosidase activity, and engagement of senescence pathways. FAP function is required for muscle cell health with changes to their phenotype potentially proving detrimental. In this respect, the transcriptomic landscape of IBM was also characterized by changes to the myogenic compartment demonstrating a pronounced loss of type 2A myofibers and a rarefication of acetylcholine receptor expressing myofibers. IBM muscle cells also engaged a specific pro-inflammatory phenotype defined by intracellular complement activity and the expression of immunogenic surface molecules. Skeletal muscle cell dysfunction may be linked to FAP senescence by a change in the collagen composition of the latter. Senescent FAPs lose collagen type XV expression, which is required to support myofibers' structural integrity and neuromuscular junction formation in vitro. Taken together, this study demonstrates an altered phenotypical landscape of muscle-resident cells and that FAPs, and not myofibers, are the primary senescent cell type in IBM.

Successful plasmapheresis and immunoglobulin treatment for severe lipid storage myopathy: Doing the right thing for the wrong reason.

Three consecutive skeletal muscle biopsies during a several months time-frame, showing different degrees of neutral lipid storage. This is highlighted by Oil-red-O stains (D, E, F) and electron microscopy (G, H, I). Note the impact on mitochondrial morphology with so called 'parking lots (K, L). Zooming 'in and out' into the ultrastructure, using the nanotomy platform provides interesting detailled information (http://nanotomy.org). ​.

Systemic sclerosis-associated myositis features minimal inflammation and characteristic capillary pathology.

Systemic sclerosis represents a chronic connective tissue disease featuring fibrosis, vasculopathy and autoimmunity, affecting skin, multiple internal organs, and skeletal muscles. The vasculopathy is considered obliterative, but its pathogenesis is still poorly understood. This may partially be due to limitations of conventional transmission electron microscopy previously being conducted only in single patients. The aim of our study was therefore to precisely characterize immune inflammatory features and capillary morphology of systemic sclerosis patients suffering from muscle weakness. In this study, we identified 18 individuals who underwent muscle biopsy because of muscle weakness and myalgia in a cohort of 367 systemic sclerosis patients. We performed detailed conventional and immunohistochemical analysis and large-scale electron microscopy by digitizing entire sections for in-depth ultrastructural analysis. Muscle biopsies of 12 of these 18 patients (67%) presented minimal features of myositis but clear capillary alteration, which we termed minimal myositis with capillary pathology (MMCP). Our study provides novel findings in systemic sclerosis-associated myositis. First, we identified a characteristic and specific morphological pattern termed MMCP in 67% of the cases, while the other 33% feature alterations characteristic of other overlap syndromes. This is also reflected by a relatively homogeneous clinical picture among MMCP patients. They have milder disease with little muscle weakness and a low prevalence of interstitial lung disease (20%) and diffuse skin involvement (10%) and no cases of either pulmonary arterial hypertension or renal crisis. Second, large-scale electron microscopy, introducing a new level of precision in ultrastructural analysis, revealed a characteristic capillary morphology with basement membrane thickening and reduplications, endothelial activation and pericyte proliferation. We provide open-access pan-and-zoom analysis to our datasets, enabling critical discussion and data mining. We clearly highlight characteristic capillary pathology in skeletal muscles of systemic sclerosis patients.

[Neurological complications of hepatitis C infections]. / Neurologische Komplikationen der Hepatitis-C-Infektion.

Chronic hepatitis C virus (HCV) infection is a highly prevalent systemic disease, which can cause a variety of neurological complications. The HCV-associated symptoms can be differentiated into central and peripheral nervous systems as well as the musculature. Important pathomechanisms are HCV-associated autoimmunity (e.g. mixed cryoglobulinemia with polyneuropathy) and direct neurotoxic effects of the virus (e.g. HCV-associated cognitive deficits). Distal symmetric polyneuropathies, small fiber neuropathies and cognitive deficits are the most prevalent neurological manifestations. Furthermore, HCV infection is a risk factor for ischemic and hemorrhagic stroke as well as Parkinson's disease. As HCV infection has become a permanently curable disease in >90% of patients, early identification and antiviral treatment of HCV positive patients is of utmost importance.

Interferon-free therapy in hepatitis C virus (HCV) monoinfected and HCV/HIV coinfected patients: effect on cognitive function, fatigue, and mental health.

The efficacy and safety of interferon-free therapies for hepatitis C virus (HCV) infection have been reported. Considering the accumulating evidence for a direct central nervous system infection by HCV, we aim to evaluate the effect of direct acting antivirals (DAA) therapy on cognitive function in HCV patients. We conducted a longitudinal analysis of the cognitive performance of 22 patients (8 HCV+, 14 HCV+/HIV+) who completed neuropsychological testing at baseline and at week 12 after DAA therapy. In 20 patients, we analyzed specific attention parameters derived from an experimental testing based on the Theory of Visual Attention (TVA). Depression, fatigue, and mental health were assessed as patient reported outcomes. At baseline, 54.5% of the patients met the criteria for cognitive impairment and 40% showed impairment in TVA parameters. Follow-up analysis revealed significant improvements in the domains of visual memory/learning, executive functions, verbal fluency, processing speed, and motor skills but not in verbal learning and attention/working memory. We did not observe significant improvement in visual attention measured by TVA. Fatigue and mental health significantly improved at follow-up. Our findings indicate that successful DAA treatment leads to cognitive improvements in several domains measured by standard neuropsychological testing. The absence of improvement in TVA parameters and of significant improvement in the domain of attention/working memory might reflect the persistence of specific cognitive deficits after HCV eradication. In summary, DAA treatment seems to have a positive effect on some cognitive domains and leads to an improvement in mental health and fatigue in HCV-infected patients.

Molecular composition of skeletal muscle in infants and adults: a comparative proteomic and transcriptomic study.

To gain a deeper understanding of skeletal muscle function in younger age and aging in elderly, identification of molecular signatures regulating these functions under physiological conditions is needed. Although molecular studies of healthy muscle have been conducted on adults and older subjects, there is a lack of research on infant muscle in terms of combined morphological, transcriptomic and proteomic profiles. To address this gap of knowledge, we performed RNA sequencing (RNA-seq), tandem mass spectrometry (LC-MS/MS), morphometric analysis and assays for mitochondrial maintenance in skeletal muscle biopsies from both, infants aged 4-28 months and adults aged 19-65 years. We identified differently expressed genes (DEGs) and differentially expressed proteins (DEPs) in adults compared to infants. The down-regulated genes in adults were associated with functional terms primarily related to sarcomeres, cellular maintenance, and metabolic, immunological and developmental processes. Thus, our study indicates age-related differences in the molecular signatures and associated functions of healthy skeletal muscle. Moreover, the findings assert that processes previously associated solely with aging are indeed part of development and healthy aging. Hence, combined findings of this study also indicate that age-dependent controls are crucial in muscle disease studies, as otherwise the comparative results may not be reliable.

Morphological and molecular comparison of HIV-associated and sporadic inclusion body myositis.

OBJECTIVE: The molecular characteristics of sporadic inclusion body myositis (sIBM) have been intensively studied, and specific patterns on the cellular, protein and RNA level have emerged. However, these characteristics have not been studied in the context of HIV-associated IBM (HIV-IBM). In this study, we compared clinical, histopathological, and transcriptomic patterns of sIBM and HIV-IBM. METHODS: In this cross-sectional study, we compared patients with HIV-IBM and sIBM based on clinical and morphological features as well as gene expression levels of specific T-cell markers in skeletal muscle biopsy samples. Non-disease individuals served as controls (NDC). Cell counts for immunohistochemistry and gene expression profiles for quantitative PCR were used as primary outcomes. RESULTS: 14 muscle biopsy samples (7 HIV-IBM, 7 sIBM) of patients and 6 biopsy samples from NDC were included. Clinically, HIV-IBM patients showed a significantly lower age of onset and a shorter period between symptom onset and muscle biopsy. Histomorphologically, HIV-IBM patients showed no KLRG1+ or CD57+ cells, while the number of PD1+ cells did not differ significantly between the two groups. All markers were shown to be significantly upregulated at gene expression level with no significant difference between the IBM subgroups. CONCLUSION: Despite HIV-IBM and sIBM sharing important clinical, histopathological, and transcriptomic signatures, the presence of KLRG1+ cells discriminated sIBM from HIV-IBM. This may be explained by longer disease duration and subsequent T-cell stimulation in sIBM. Thus, the presence of TEMRA cells is characteristic for sIBM, but not a prerequisite for the development of IBM in HIV+ patients.

Inclusion body myositis and associated diseases: an argument for shared immune pathologies.

Inclusion body myositis (IBM) is the most prevalent idiopathic inflammatory myopathy (IIM) affecting older adults. The pathogenic hallmark of IBM is chronic inflammation of skeletal muscle. At present, we do not classify IBM into different sub-entities, with the exception perhaps being the presence or absence of the anti-cN-1A-antibody. In contrast to other IIM, IBM is characterized by a chronic and progressive disease course. Here, we discuss the pathophysiological framework of IBM and highlight the seemingly prototypical situations where IBM occurs in the context of other diseases. In this context, understanding common immune pathways might provide insight into the pathogenesis of IBM. Indeed, IBM is associated with a distinct set of conditions, such as human immunodeficiency virus (HIV) or hepatitis C-two conditions associated with premature immune cell exhaustion. Further, the pathomorphology of IBM is reminiscent of other muscle diseases, notably HIV-associated myositis or granulomatous myositis. Distinct immune pathways are likely to drive these commonalities and senescence of the CD8+ T cell compartment is discussed as a possible mechanism of pathogenesis. Future effort directed at understanding the co-occurrence of IBM and associated diseases could prove valuable to better understand the enigmatic IBM pathophysiology.

Same same, but different? The neurological presentation of wildtype transthyretin (ATTRwt) amyloidosis.

BACKGROUND: Both hereditary transthyretin (ATTRv) amyloidosis and wildtype transthyretin (ATTRwt) amyloidosis can be associated with neurological diseases such as carpal tunnel syndrome and polyneuropathy. While ATTRv amyloidosis has been extensively studied, to date little is known about neurological complications of ATTRwt amyloidosis. In particular, the prevalence, pattern and extent of polyneuropathy and autonomic dysfunction has not been adequately investigated in the context of ATTRwt amyloidosis. To tackle this issue, we aimed to characterise the neurological presentation of ATTRwt amyloidosis and to compare between the presentations of ATTRv and ATTRwt amyloidoses. PATIENTS AND METHODS: Between November 2019 and September 2020, we included 50 patients with ATTRwt amyloidosis in this cohort study. All patients presented to the amyloidosis centre in Berlin, Germany and underwent neurological, cardiological and radiological work-up including neurological examination, laboratory testing, nerve conduction studies (NCS), echocardiography and scintigraphy. Patients were screened for symptoms of autonomic dysregulation and a subgroup of patients underwent tilt-table testing for orthostatic dysregulation. RESULTS: The cohort included 46 men and 4 women; the mean age of the study participants was 80.6 (standard deviation [SD] ± 5.0) years. All patients showed signs of cardiomyopathy on echocardiography. Neurological examination revealed peripheral, symmetric and length-depended predominately sensory polyneuropathy in 74% (n = 37) of patients. Neuropathy impairment scores (NIS) ranged from 0 to 50 with an average score of 8.4 (SD ± 10.1) indicating mild to moderate impairment. 90% and 92% of patients were classified as FAP stage I and PND stage I, respectively. Unilateral or bilateral carpal tunnel syndrome (CTS) was present in 70% (n = 35) and spinal stenosis was seen in 11% (n = 5) of patients. We detected a low rate of autonomic symptoms with a median COMPASS-31 total score of 18.4 points (IQR 32.4 points). Additional tilt-table testing of a subgroup of 8 patients yielded negative results for orthostatic intolerance. CONCLUSION: Distal-symmetric, predominantly sensory polyneuropathy is a common neurological complication in ATTRwt amyloidosis besides carpal tunnel syndrome and spinal stenosis, further substantiating the systemic character of the disease. Compared to ATTRv amyloidosis, the severity of polyneuropathy in ATTRwt amyloidosis is milder and without relevant motor involvement. Symptoms of autonomic dysfunction were not common in this cohort. Nevertheless, ATTRwt amyloidosis is a treatable disease and should be included in the differential diagnosis of sensory polyneuropathy in the elderly.

Morphologic and Molecular Patterns of Polymyositis With Mitochondrial Pathology and Inclusion Body Myositis.

BACKGROUND AND OBJECTIVE: To characterize morphological and molecular underpinnings of polymyositis with mitochondrial pathology (PM-Mito) in comparison with sporadic inclusion body myositis (IBM) and to define common and distinct pathophysiologic features with a focus on interferon (IFN)-associated inflammation and T-cell response. METHODS: In this cross-sectional study, skeletal muscle biopsy samples and clinical and laboratory data from patients with PM-Mito and IBM were analyzed at Charité university hospital in Berlin, Germany. All available PM-Mito biopsy samples, an equal number of randomly selected IBM biopsy samples, and randomly selected nondiseased controls (NDCs) were included in the study. Biopsy samples were studied by histopathology, immunohistochemistry, and quantitative PCR (qPCR) and compared with biopsies derived from NDCs. Primary outcomes included cell counts for immunohistochemistry and gene expression (fold-change values compared with those in NDCs) for qPCR. RESULTS: Twenty-five skeletal muscle biopsy samples of patients with PM-Mito and IBM were included in the study and compared with 5 biopsy samples from NDCs. PM-Mito and IBM qualitatively harbored a strikingly similar molecular signature and shared important histopathologic features. Expression of IFN-induced guanylate-binding protein (GBP)6 and T-cell function-related KLRG1 distinguished IBM from PM-Mito biopsies with IBM patients showing significantly higher expression of GBP6 and KLRG1. Cryptic exon expression was detected in both patient groups with IBM patients showing higher expression levels. Skeletal muscle biopsies from IBM patients showed significantly more GBP6+ cells and KLRG1+ lymphocytes in comparison with biopsies from patients with PM-Mito. CD45+, CD68+, CD57+, PD1+, and CD8+ cytotoxic T cells were also significantly more abundant in patients with IBM. Clinically, patients with PM-Mito presented with a spectrum of muscle-related symptoms including myalgia, proximal paraparesis, proximal tetraparesis, and incomplete IBM-like patterns. Thirteen of 14 (93%) patients with PM-Mito for whom clinical follow-up was available later developed clinically defined IBM. Notably, 2 follow-up biopsies obtained 5 and 7 years after the first ones were available in this cohort, both showing histopathologic progress to net IBM including GBP6 and KLRG1 upregulation. DISCUSSION: Our combined data suggest that specific IFN-mediated inflammation plays a key role in both IBM and PM-Mito. GBP6 was identified as a new molecule of type II IFN-induced inflammation distinguishing IBM from PM-Mito. Skeletal muscles from both groups harbor dysfunctional T cells of similar type, albeit in different quantity. T-cell senescence exemplified by KLRG1 positivity does not play a significant role in PM-Mito. Based on these findings, we propose to include PM-Mito in the spectrum of IBM (IBM-spectrum disease [IBM-SD]) as a possible early form of this disease. The establishment of IBM-SD as a larger entity could potentially have a significant effect on the design of trials and therapeutic interventions.

Performance of ENMC and EULAR/ACR classification systems applied to a single tertiary center cohort of dermatomyositis patients.

BACKGROUND: There have been numerous classification systems to diagnose corresponding myositis subtypes and select appropriate therapeutic measures. However, the lack of a broad consensus on diagnostic criteria has led to clinical uncertainties. The objective of this study was to compare two commonly used dermatomyositis-classification systems regarding their clinical practicability and to point out their specific advantages and disadvantages. METHODS: This study included 30 patients diagnosed with dermatomyositis at the Charité university hospital, Berlin, Germany from 2010 to 2017. Patient files with complete data and defined historical classifications were enrolled and ENMC (2003) and EULAR/ACR (2017) criteria retrospectively applied. RESULTS: According to the ENMC approach, 14 patients were classified as "definite" and 12 as "probable" dermatomyositis. One patient exhibited an "amyopathic dermatomyositis" and three a "DM without dermatitis". Regarding the criteria probability of the EULAR/ACR set, 16 patients had a "high", 13 a "medium" and one a "low probability". There was a significant difference (p = 0.004) between the subclasses of the ENMC in relation to the EULAR/ACR score. The agreement between the classification probabilities of "definite/high" (κ = 0.400) and "possible/medium" (κ = 0.324) was fair. CONCLUSIONS: It is important to find a consensus among the medical disciplines involved and to establish a structured procedure. Future studies with newer approaches are warranted to conclusively decide which system to use for the physician.

Familial Oculo-Leptomeningeal Transthyretin Amyloidosis Caused by Leu55Arg Mutation.

Hereditary transthyretin amyloidosis (hATTR amyloidosis) is a multisystemic disease usually presenting in a mixed neurological and cardiological phenotype. We present a case of hATTR amyloidosis associated with Leu55Arg mutation causing a form of familial oculo-leptomeningeal amyloidosis. Two brothers and their mother presented with severe autonomic neuropathy, loss of visual acuity and lepto-meningeal involvement. One patient suffered subarachnoid hemorrhage as a possible complication of cerebral involvement. The patients suffered from treatment-refractory weight loss and recurring vitreous opacities. RNA interference-based treatment has led to stabilization of autonomic and peripheral neuropathy but has had no effect on ocular symptoms.

Isolated atrial amyloidosis suspected by electrophysiological voltage mapping and diagnosed by 99m Tc-DPD scintigraphy.

We present not-yet-seen multimodal images of a 55-year-old female patient with isolated atrial amyloidosis (IAA) who clinically suffered from multiple atrial arrhythmias and heart failure symptoms with preserved left ventricular ejection fraction. We aim to show structural and functional abnormalities detected by electrophysiological voltage mapping, cardiac magnetic resonance imaging (MRI) [cMRI; atrial strain measurements, late gadolinium enhancement (LGE) visualization], and 99m Tc-DPD scintigraphy. Bipolar voltage mapping performed during two electrophysiological procedures showed diffuse left atrial low-voltage areas (bipolar < 0.5 mV) and also a moderately diseased right atrium suspected of infiltrative cardiomyopathy. Catheter ablation did successfully treat a left atrial and two right atrial focal tachycardias. For further diagnostics, a 3T cMRI was performed, revealing a subendocardial circumferential left atrial LGE and pathological atrial strain measurements, especially during conduit and reservoir phase. Afterwards, nuclear imaging with 559 MBq of 99m Tc-DPD was performed. The scan revealed amyloid infiltration of the left atrium. Neither an uptake in the ventricular myocardium nor an extra-cardiac uptake of DPD was seen. Genetic testing for transthyretin amyloidosis mutations in this patient was negative, and peripheral neuropathy was ruled out by electromyogram analysis. The synopsis of these findings reveals IAA as the most possible diagnosis and showed isolated atrial nuclear tracer uptake with 99m Tc-DPD scintigraphy for the first time. Non-invasive imaging techniques might help in suggesting IAA but need further investigation.