Joint and muscle inflammatory disease: A scoping review of the published evidence

OBJECTIVES

Polyarthritis is commonly reported in idiopathic inflammatory myositis patients, but few studies have focused on the overlap of myositis with rheumatoid arthritis which is a difficult diagnosis in the absence of well-defined diagnostic criteria. The primary objective of this scoping review was to map the field of research to explore the potential diagnoses in patients presenting with both myositis and polyarthritis.

METHODS

Two electronic databases (MEDLINE/PubMed® and Web of Science®) were systematically searched using the terms (myositis OR 'inflammatory idiopathic myopathies') AND (polyarthritis OR 'rheumatoid arthritis') without any publication date limit.

RESULTS

Among individual records, 280 reports met inclusion criteria after full-text review. There was heterogeneity in the definition of overlap myositis as well as the characteristics of rheumatoid arthritis. In many studies, key data were lacking; rheumatoid factor status was reported in 56.8% (n=151), anti-citrullinated proteins antibodies status in 18.8% (n=50), and presence or absence of bone erosions in 45.1% (n=120) of the studies. Thirteen different diagnoses were found to associate myositis with polyarthritis: antisynthetase syndrome (29.6%, n=83), overlap myositis with rheumatoid arthritis (16.1%, n=45), drug-induced myositis (20.0%, n=56), rheumatoid myositis (7.5%, n=21), inclusion body myositis (1.8%, n=5), overlap with connective tissue disease (20.0%, n=56), and others (5.0%, n=14).

CONCLUSION

The spectrum of joint and muscle inflammatory diseases encompasses many diagnoses including primitive and secondary myositis associated with RA or arthritis mimicking RA. This review highlights the need for a consensual definition of OM with RA to better individualise this entity from the numerous differential diagnoses.

[Clinical and immunological characteristics of 88 cases of overlap myositis]

OBJECTIVE

To investigate the clinical and immunological characteristics of overlap myositis (OM) patients.

METHODS

The data of 368 patients with idiopathic inflammatory myopathies (IIMs) admitted to Peking University People's Hospital from January 2004 to August 2020 were analyzed retrospectively, including demographic characteristics, clinical characteristics (including fever, Gottron' s sign/papules, Heliotrope rash, V-sign, Shawl sign, Mechanic' s hands, skin ulceration, periungual erythema, subcutaneous calcinosis, dysphagia, myalgia, myasthenia, arthritis, Raynaud' s phenomenon, interstitial lung disease, pulmonary hypertension and myocardial involvement), laboratory characteristics, immunological characteristics [including antinuclear antibodies, rheumatoid factors, myositis-associated autoantibodies (MAAs) and myositis-specific autoantibodies (MSAs)] and survival. The clinical and immunological characteristics and prognostic differences of OM and non-OM were compared. The Kaplan-Meier and Log Rank methods were used to analyze the survival.

RESULTS

A total of 368 patients were included. 23.9% (88/368) of IIMs patients were OM patients. Among the 88 OM patients, 85.2% (75/88) of them were female, and the median interval between disease onset and diagnosis was 13.5 months. The incidence of overlapped connective tissue diseases in the OM patients was dermatomyositis (DM) in 60.2%, polymyositis (PM) in 3.4%, immune-mediated necrotizing myopathy (IMNM) in 2.3% and anti-synthetase syndrome (ASS) in 34.1%. Compared with the non-OM patients, the proportion of the females in the OM patients was higher (85.2% vs. 72.1%, P=0.016), the OM patients had longer disease duration [13.5(4.5, 48.0) months vs. 4.0(2.0, 12.0) months, P < 0.001]. As for clinical characteristics, compared with the non-OM patients, the incidence of V-sign (25.0% vs. 44.6%, P=0.001) and periungual erythema (8.0% vs. 19.6%, P=0.013) were lower; the incidence of Raynaud's phenomenon (14.8% vs. 1.8%, P < 0.001), interstitial pneumonia (88.6% vs. 72.1%, P=0.001), pulmonary hypertension (22.7% vs. 7.5%, P < 0.001) and myocardial involvement (18.2% vs. 9.3%, P=0.033) were higher. As for immunological characteristics, compared with the non-OM patients, the incidence of elevated aspartate aminotransferase (AST) (31.8% vs. 45.0%, P=0.035) was lower and elevated C-reactive protein (CRP) (58.0% vs. 44.6%, P=0.037) was higher; the positive rates of antinuclear antibodies (ANA) (85.1% vs. 63.4%, P=0.001) and rheumatoid factors (RF) (40.2% vs. 17.8%, P < 0.001) and anti-Ro-52 (71.6% vs. 56.1%, P=0.038) in serum were higher. There was no significant difference in the survival between the OM patients and non-OM patients.

CONCLUSION

Pulmonary hypertension and myocardial involvement were frequently observed in OM.

Peripheral nervous system manifestations of rheumatological diseases

Rheumatological diseases result in immune-mediated injury to not only connective tissue, but often components of the peripheral nervous system. These overlap conditions can be broadly categorized as peripheral neuropathies and overlap myositis. The peripheral neuropathies are distinctive as many have unusual presentations such as non-length-dependent, small fiber neuropathies and sensory neuronopathies (both due to dorsal root ganglia dysfunction), multiple mononeuropathies (e.g. vasculitic neuropathies), and even cranial neuropathies. Overlap myositis is increasingly recognized and is often associated with specific autoantibodies. Sarcoidosis also has widespread neurological manifestations and impacts both the peripheral nerves and muscle. Much work is needed to fully characterize the vast presentations of these overlap diseases. Given the rarity of these disorders, they are understudied, resulting in significant knowledge gaps with regards to their underlying pathophysiology and the best treatment approach. A basic knowledge of these disorders is mandatory for both practicing rheumatologists and neurologists as prompt recognition and early initiation of immunotherapy may prevent significant morbidity and permanent disability.

Inflammatory Myopathies: Utility of Antibody Testing

Inflammatory myopathies are a group of immune-mediated muscle disorders comprising dermatomyositis; polymyositis; overlap myositis, including antisynthetase syndromes and nonspecific myositis, immune-mediated necrotizing myopathies, and sporadic inclusion body myositis. They are now much more eloquently classified both pathologically and clinically because of the discovery of several myositis-specific and myositis-associated antibodies. These antibodies also aid in choosing the best treatment options in each case. Based on the initial classifications of inflammatory myopathies, inclusion body myositis, overlap myositis, and necrotizing myositis were all included in the polymyositis group. This article discusses cases, diagnostic tools, associated antibodies, and pathology.

Secondary Causes of Myositis

Purpose of review

The purpose of this paper is to comprehensively evaluate secondary causes of inflammatory myopathies (myositis) and to review treatment options.

Recent findings

This review highlights recent advancements in our understanding of known causes of myositis, including newer drugs that may cause myositis such as checkpoint inhibitors and viruses such as influenza, HIV, and SARS-CoV2. We also discuss treatment for malignancy-associated myositis and overlap myositis, thought to be a separate entity from other rheumatologic diseases.

Summary

Infections, drugs, rheumatologic diseases, and malignancies are important causes of myositis and are important to diagnose as they may have specific therapies beyond immunomodulatory therapy.

The spectrum of idiopathic inflammatory myopathies in South Africa

INTRODUCTION

There are many reports on idiopathic inflammatory myopathies (IIM) but little information from sub-Saharan Africa. We conducted a retrospective study of IIM in a multi-ethnic cohort seen at a single centre in Durban, South Africa.

METHOD

The study included patients who fulfilled the Bohan and Peter or European League Against Rheumatism/American College of Rheumatology criteria for IIM. The information recorded included demographic data, clinical findings, results of investigations, treatment and outcome. Patients with overlap myositis (OM) had myositis and criteria for another connective tissue disease.

RESULTS

There were 104 patients with IIM; 82.7% female and 70.2% African blacks. They included 41 (39.4%) with OM, 26 (25%) polymyositis (PM), 26 (25%) dermatomyositis (DM), six (5.8%) juvenile dermatomyositis and five (4.8%) cancer-associated myositis. Our patients had a younger mean age at diagnosis (36.8 ± 14.7 years) compared with 45-55 years in most other studies. Scleroderma-myositis overlap accounted for 26 (63.4%) of the patients with OM. Patients with OM were significantly younger than PM (p = 0.004) and DM (p = 0.044) and had lower, but not statistically significant, creatine kinase levels at diagnosis compared with PM (p = 0.052) and DM (p = 0.073). Interstitial lung disease was more common in OM (p = 0.001) and PM (p = 0.024) than DM. Oropharyngeal weakness was more common in DM than OM (p = 0.001) and PM (p = 0.032). African blacks were younger (p = 0.028) at diagnosis and had more cardiac abnormalities (p = 0.034) than Indians.

CONCLUSION

The spectrum of IIM in our cohort of mainly African blacks is similar to other studies, with OM being the most frequent subtype. Key Points • As there is limited information on idiopathic inflammatory myopathies (IIM) in sub-Saharan Africa, this study reports the spectrum of IIM in a South African cohort of predominantly African blacks. • Our patients were younger at diagnosis, and overlap myositis was the most common phenotype. • Comparisons with other studies show similarities in the manifestations of IIM.

Developments in the classification and treatment of the juvenile idiopathic inflammatory myopathies

This review updates recent trends in the classification of the juvenile idiopathic inflammatory myopathies (JIIM) and the emerging standard of treatment of the most common form of JIIM, juvenile dermatomyositis. The JIIM are rare, heterogeneous autoimmune diseases that share chronic muscle inflammation and weakness. A growing spectrum of clinicopathologic groups and serologic phenotypes defined by the presence of myositis autoantibodies are now recognized, each with differing demographics, clinical manifestations, laboratory findings, and prognoses. Although daily oral corticosteroids remain the backbone of treatment, disease-modifying anti-rheumatic drugs are almost always used adjunctively and biologic therapies may benefit patients with recalcitrant disease.