Frequency and spectrum of myopathies in patients with psoriasis

Novel aspects of muscle involvement in immune-mediated inflammatory arthropathies and connective tissue diseases

Myalgia, myopathy and myositis are the most important types of muscle impairment in immune-mediated inflammatory arthropathies and connective tissue diseases. Multiple pathogenetic and histological changes occur in the striated muscles of these patients. Clinically, the most important muscle involvement is the one that causes complaints to the patients. In everyday practice, insidious symptoms present a serious problem for the clinician; in many cases, it is difficult to decide when and how to treat the muscle symptoms that are often present only subclinically. In this work, authors review the international literature on the types of muscle problems in autoimmune diseases. In scleroderma histopathological picture of muscle shows a very heterogeneous picture, necrosis and atrophy are common. In rheumatoid arthritis and systemic lupus erythematosus, myopathy is a much less defined concept, further studies are needed to describe it. According to our view, overlap myositis should be recognized as a separate entity, preferably with distinct histological and serological characteristics. More studies are needed to describe muscle impairment in autoimmune diseases which may help to explore this topic more in depth and be of clinical use.

Focal myositis: New insights on diagnosis and pathology

OBJECTIVE

To better define in a cohort study the clinical and pathologic features of focal myositis (FM).

METHODS

With the use of the usual clinicopathologic definition, each confirmed case of FM in the Lyon University Hospital's myopathologic database between 2000 and 2016 was retrieved. Clinical, pathologic, imaging, serologic, and therapeutic data were collected. When data were missing but feasible, appropriate pathologic analyses were performed.

RESULTS

Of the 924 patients included in the database, 37 (4%) had confirmed FM (14 female, 23 male patients). The main symptoms were pain (n = 30, 81%), muscular mass (n = 16, 43%), erythema at the site of FM (n = 12, 32%), and fever (n = 9, 24%). Serum creatine kinase was normal in most patients (81%); serum immune abnormalities were frequent (inflammatory syndrome in sera [39%], dysglobulinemia [52%], and anti-nuclear antibody positivity [29%]). In addition to confirming previously reported findings, pathologic analyses found significant rates of vasculitis (68%) and fasciitis (73%). Here, FM appeared frequently to be associated with other diseases such as immune-mediated inflammatory disease (IMID; 32%), neoplasia (24%), and radiculopathy (11%). Regarding outcomes, 64% of the cases had received immunosuppressive drugs, and the relapse rate was 41%.

CONCLUSION

The present study suggests that FM is not as innocuous as previously believed, particularly considering the associated disorders. Notably, patients with FM should receive careful IMID and neoplasia screening.

Secondary myopathy due to systemic diseases

Background

Some systemic diseases also affect the skeletal muscle to various degrees and with different manifestations. This review aimed at summarizing and discussing recent advances concerning the management of muscle disease in systemic diseases.

Method

Literature review by search of MEDLINE, and Current Contents with appropriate search terms.

Results

Secondary muscle disease occurs in infectious disease, endocrine disorders, metabolic disorders, immunological disease, vascular diseases, hematological disorders, and malignancies. Muscle manifestations in these categories include pathogen‐caused myositis, muscle infarction, rhabdomyolysis, myasthenia, immune‐mediated myositis, necrotising myopathy, or vasculitis‐associated myopathy. Muscle affection may concern only a single muscle, a group of muscles, or the entire musculature. Severity of muscle affection may be transient or permanent, may be a minor part of or may dominate the clinical picture, or may be mild or severe, requiring invasive measures including artificial ventilation if the respiratory muscles are additionally involved. Diagnostic work‐up is similar to that of primary myopathies by application of non‐invasive and invasive techniques. Treatment of muscle involvement in systemic diseases is based on elimination of the underlying cause and supportive measures. The prognosis is usually fair if the causative disorder is effectively treatable but can be fatal in single cases if the entire musculature including the respiratory muscles is involved, in case of infection, or in case of severe rhabdomyolysis.

Conclusion

Secondary muscle manifestations of systemic diseases must be addressed and appropriately managed. Prognosis of secondary muscle disease in systemic diseases is usually fair if the underlying condition is accessible to treatment.

Focal myositis: A review

Amongst the heterogeneous group of inflammatory myopathies, focal myositis stands as a rare and benign dysimmune disease. Although it can be associated with root and/or nerve lesions, traumatic muscle lesions and autoimmune diseases, its triggering factors remain poorly understood. Defined as an isolated inflammatory pseudotumour usually restricted to one skeletal muscle, clinical presentation of focal myositis is that of a rapidly growing solitary mass within a single muscle, usually in the lower limbs. Electromyography shows spontaneous activity associated with a myopathic pattern. MRI reveals a contrast enhanced enlarged muscle appearing hyper-intense on FAT-SAT T2 weighted images. Adjacent structures are spared and there are no calcifications. Serum creatine kinase (CK) levels are usually moderately augmented and biological markers of systemic inflammation are absent in most cases. Pathological histological features include marked variation in fibre size, inflammatory infiltrates mostly composed of T CD4+ lymphocytes and macrophages, degenerating/regenerating fibres and interstitial fibrosis. Differential diagnoses are numerous and include myositis of other origin with focal onset. Steroid treatment should be reserved for patients who present with major pain, nerve lesions, associated autoimmune disease, or elevated C reactive protein or CK.