Clinical Characteristics and Management of Patients With Clinical Amyopathic Dermatomyositis: A Retrospective Study of 64 Patients at a Tertiary Dermatology Department

Autophagy in myositis, a dysregulated pathway, and a target for therapy

Corticosteroids and immunosuppressants are the mainstay of therapy for idiopathic inflammatory myopathies (IIMs). However, a significant therapeutic challenge extends beyond mitigating inflammation with these agents in achieving meaningful improvements in muscle strength and physical function, a goal that remains largely unmet. IIMs encompass a heterogeneous group of autoimmune disorders, including dermatomyositis, polymyositis, necrotizing autoimmune myopathy, inclusion body myositis, and others, characterized by chronic muscle inflammation, progressive weakness, and fatigue. The etiology of IIMs remains poorly understood, though potential contributors include environmental triggers (e.g., infections, medications, or injury) and genetic predisposition. To advance the development of novel therapeutic strategies, it is critical to elucidate the dysfunctional molecular and cellular pathways underlying IIM pathogenesis. Among these, dysregulated autophagy pathways have emerged as a promising target for therapeutic intervention. Specifically, impairments in lysosomal autophagy and mitophagy have been implicated in IIMs, and modulating these processes through targeted regulatory mechanisms may offer therapeutic benefits. This review provides a comprehensive synthesis of clinical and biological features of IIMs, the current diagnostic approaches and emerging biomarkers, evaluates the utility of existing biomarkers, and examines the relevance of animal models in IIM research. Furthermore, we explore the role of autophagic dysregulation in disease pathogenesis and provide a critical appraisal of current treatment modalities. Finally, we highlight emerging therapeutic targets and regulatory molecules under investigation, with a particular focus on autophagy modulation. Notably, autophagy inhibitors represent a novel and potentially transformative therapeutic avenue for patients with IIMs, offering hope for improved clinical outcomes.

Characteristics of Patients With Adult-Onset Dermatomyositis at 2 Tertiary Care Centres in Ontario, Canada

Dermatomyositis (DM) is an idiopathic inflammatory myopathy characterized by progressive muscle weakness and distinctive cutaneous findings. The exact incidence and prevalence of DM in the general population is largely unknown, and data on demographic and clinical features in patients in Canada are lacking. This study aimed to comprehensively evaluate the patients with DM in Southwestern Ontario, Canada. A retrospective chart review was conducted for patients with adult-onset DM at 2 tertiary care centres in Ontario, Canada, over a 13 year period. One hundred fourteen patients were included. The mean age was 59, and 80% of patients were female. Skin and muscle involvement coincided in 63% of patients, while skin predated muscle involvement in 11%. Most common characteristic skin manifestations included Gottron's papules (69%), Heliotrope sign (66%), V sign (61%), and Shawl sign (56%). Among the 114 patients, 88 (77%) were myopathic while 26/114 (23%) were clinically amyopathic dermatomyositis. In the myopathic type, upper extremity weakness, lower extremity weakness, and dysphagia were present in 87%, 81%, and 29% of patients, respectively. Elevated creatine kinase, C-reactive protein, lactate dehydrogenase, and erythrocyte sedimentation rate were found in 66%, 35%, 33%, and 32%, respectively. Lung disease was reported in 39%, particularly interstitial lung disease. Other associated features included malignancy, cardiovascular disease, and less commonly gastrointestinal disease. DM is a multifaceted autoimmune disease with distinct cutaneous and muscular findings. Our study results align with the growing body of evidence supporting DM as a complex systemic disease with the potential involvement of other organs such as the pulmonary, cardiovascular, and gastrointestinal systems.

A Clinical Picture of Amyopathic Dermatomyositis

Clinically amyopathic dermatomyositis (CADM) is a rare subset of classic dermatomyositis (DM) with distinct clinical features and unique autoantibody profiles. Affected individuals usually present with the cutaneous signs of DM, without muscle pain, proximal weakness, or abnormal muscle labs and imaging results. Here, we present the case of a 69-year-old Caucasian male for evaluation of a positive antinuclear antibody (ANA) test and an eight-month history of a rash. He had no associated muscle weakness or pain. A physical examination noted a rash characteristic of dermatomyositis, including pathognomonic Gottron's papules. Skin biopsies were inconclusive, and labs were negative for anti-Jo1 antibodies or elevated muscle enzymes. Treatment was first initiated with hydroxychloroquine before ultimately being switched to methotrexate, which was more effective for him.

Clinically amyopathic dermatomyositis: Clinical, laboratory, and histopathological features

BACKGROUND

Despite the advancements in the categorization of clinically amyopathic dermatomyositis (CADM), the classification and diagnosis of its subtypes are still challenging. The aim of our study was to describe the clinicopathological features of CADM and assess the differences between amyopathic dermatomyositis (ADM) and hypomyopathic dermatomyositis (HDM).

METHODS

This retrospective study included 43 patients with CADM diagnosed at our institution from 2016 to 2020. Patients were subclassed into ADM (n = 30) and HDM (n = 13) groups to assess their clinicopathological differences.

RESULTS

All included patients had characteristic cutaneous manifestations of dermatomyositis; 67.4% had myositis-associated auto-antibodies, including ANA (32.6%), RNP (14.0%), anti-Ro52 (9.3%), anti-p155/140 (7.0%), rheumatoid factor (7.0%), anti-NXP-2 (4.7%), anti-MDA5 (2.3%), and anti-Jo-1 (2.3%) antibodies. One patient had associated interstitial lung disease, and another patient had oral squamous cell carcinoma. The histopathological findings included mucin deposition (69.8%), telangiectasia (65.1%), lymphocytic infiltrate (48.8%), vacuolar interface dermatitis (46.5%), and epidermal atrophy (14.0%). Compared to patients with HDM, ADM patients were significantly less likely to have epidermal atrophy, 3.3% versus 38.5% (p = 0.006), and more likely to have mucin deposition, 80.0% versus 46.2% (p = 0.028).

CONCLUSION

We described the clinicopathological features of CADM and highlighted the distinctions between ADM and HDM dermatopathologic findings. This information may prove helpful in diagnosing ambiguous lesions.

Amyopathic Dermatomyositis Presenting with Digital Ulcerations: Case Report and Literature Review

ABSTRACT

Clinically amyopathic dermatomyositis (CADM) is a rare subtype of dermatomyositis that presents with cutaneous features and no muscle involvement. This case report describes a 26-year-old woman with recurrent and multiple digital ulcerations coinciding with the start of winter each year. There was no evidence of myopathy, and antibody testing yielded negative results. A diagnosis of CADM was ultimately made based on clinicopathologic correlation. The patient's ulcers demonstrated excellent response to a combination therapy of hydroxychloroquine and potent topical and systemic steroids. Herein, the authors discuss the pathologic and immunologic characteristics of CADM.

Anti-nuclear matrix protein 2 antibody-positive amyopathic dermatomyositis presenting in a patient with prostate cancer: A case report

Nuclear matrix protein (NXP-2) positive amyopathic dermatomyositis (DM) may present without classic symptoms like muscle weakness, dysphagia, and edema, and mimic conditions like cutaneous lupus. Given DM's association with malignancy and interstitial lung disease, prompt and accurate diagnosis is important. Testing for myositis-specific antibodies aids diagnosis in ambiguous cases.

Antibodies against Small Ubiquitin-like Modifier Activating Enzyme May Be a Protective Factor from Rapid Progressive Interstitial Lung Disease in Patients Bearing Antibodies against Melanoma Differentiation Associated Gene 5

Background: Anti-MDA5 antibody-bearing (anti-MDA5+)-dermatomyositis (DM) or polymyositis (PM) is notorious for causing rapidly progressive interstitial lung disease (RPILD) and/or cancers with high mortality rate. However, anti-MDA5 antibodies (Abs) are also found in other connective tissue diseases and their link with RPILD, especially with regard to the mortality rate, are unknown. Methods: We retrospectively recruited 71 patients bearing anti-MDA5-Abs in serum, stratified them in terms of a presence or absence of RPILD, and evaluated their clinical features, laboratory findings, associated myositis antibodies, concurrent connective tissue disease (CTD) as well as newly developed malignancies. Results: In total, 39 (55%) patients presented with DM/PM, but 32 (45%) did not. In total, 22 of the former and 11 of the latter developed RPILD eventually, accounting for a total of 46% of all MDA-5 bearing patients. On the other hand, 15 of all 71 (21.1%) patients had cancers. Among the 32 patients who did not have DM/PM, 27 (38.0% of all 71) had other CTDs, indicating that only 5 (7.0% of 71) patients did not have CTDs. Senility (odds ratio (OR) = 1.816, p = 0.032), presence of anti-Ro-52 antibody (OR = 1.676, p = 0.018), elevated C-reactive protein (CRP, OR = 4.354, p < 0.001) and carcinoembryonic antigen (CEA, OR = 2.625, p = 0.005) posed risks for RPILD. High lactose dehydrogenase (LDH, p = 0.009), CRP (p = 0.001) and CEA (p = 0.001), ferritin (p ≤ 0.001) and low albumin (p ≤ 0.001) were significantly associated with mortality. Anti-SAE antibodies were negatively correlated with RPILD as analyzed by univariate (OR = 0.245, p = 0.017) and multivariate (OR = 0.058, p = 0.036) regressions, indicating that they may be a protective factor in relation to RPILD (OR = 0.543, p = 0.008) or fatality (OR = 0.707, p = 0.012), which was also demonstrated in subgroup analyses. Conclusions: In contrast to various risk factors for RPILD or mortality, anti-SAE antibodies might conversely be a protective factor in anti-MDA5+ patients.

Pregnancy in adult-onset dermatomyositis/polymyositis: a systematic review

Idiopathic inflammatory myopathy in pregnancy is uncommon but may result in complications for both mother and the fetus. In this systematic review, we summarized the current literature investigating outcomes of pregnancy related to the dermatomyositis/polymyositis (DM/PM) process. We searched PubMed, Embase, Cochrane Library, and Web of Science databases and included 61 studies reporting the disease course, pregnancy outcomes, and management of both pregnancy and DM/PM in the final analysis. The specific information of 221 pregnancies was extracted and these pregnancies were divided into three distinct forms: pregnancies after disease onset (n = 159), pregnancies with new disease onset (n = 37), and pregnancies followed by postpartum onset (n = 25). In most cases, DM/PM disease activity remained stable or improved throughout pregnancy (80.2%) and the postpartum period (83.9%). Active DM/PM during pregnancy significantly increased the risk of stillbirth or neonatal death (12% vs. 1%, P = 0.005) and preterm birth (34.7% vs. 11%, P<0.001). The rates of other poor outcomes (total fetal loss, low birth weight, and intrauterine growth retardation) were also increased in pregnancies with active disease. Mainstay treatments for active DM/PM during pregnancy are glucocorticoids and intravenous immunoglobins. The present results underline the importance of good control of myopathy in optimizing the pregnancy outcomes of women with DM/PM. This article is protected by copyright. All rights reserved.

[Dermatomyositis and juvenile dermatomyositis]

Dermatomyositis (DM) is an inflammatory multisystem disease of unknown etiology, which can already occur in children but first onset can also be in older adulthood. Myalgia and muscle weakness can occur later in the course of the disease or even be completely absent in some forms. Classical signs on the skin include heliotrope rash, facial erythema, Gottron's papules and nailfold capillary abnormalities. For the diagnosis, screening for the presence of myositis-specific autoantibodies has become increasingly more relevant. Muscle enzymes may be elevated but not in approximately one third of patients. In the absence of typical clinical or serologic findings, additional examination methods such as nailfold capillaroscopy, magnetic resonance imaging, electromyography, skin or muscle biopsies may help to establish the diagnosis. Depending on the clinical and serological subtype, additional screening for gastrointestinal or cardiopulmonary involvement should be considered. In adults, an age-appropriate tumor screening should also be performed. Apart from corticosteroids as induction therapy, biologics and small molecule inhibitors are gaining in importance in addition to conventional disease-modifying anti-rheumatic drugs and intravenous immunoglobulins. The prognosis for DM and juvenile DM (JDM) has improved. Most patients recover at least to some extent; however, a few patients die and a minority develop persisting muscle atrophy or severe calcinosis.