Inflammatory myopathies: Clinical, diagnostic and therapeutic aspects

Abstract

The three major forms of immune-mediated inflammatory myopathy are dermatomyositis (DM), polymyositis (PM), and inclusion-body myositis (IBM). They each have distinctive clinical and histopathologic features that allow the clinician to reach a specific diagnosis in most cases. Magnetic resonance imaging is sometimes helpful, particularly if the diagnosis of IBM is suspected but has not been formally evaluated. Myositis-specific antibodies are not helpful diagnostically but may be of prognostic value; most antibodies have low sensitivity. Muscle biopsy is mandatory to confirm the diagnosis of an inflammatory myopathy and to allow unusual varieties such as eosinophilic, granulomatous, and parasitic myositis, and macrophagic myofasciitis, to be recognized. The treatment of the inflammatory myopathies remains largely empirical and relies upon the use of corticosteroids, immunosuppressive agents, and intravenous immunoglobulin, all of which have nonselective effects on the immune system. Further controlled clinical trials are required to evaluate the relative efficacy of the available therapeutic modalities particularly in combinations, and of newer immunosuppressive agents (mycophenolate mofetil and tacrolimus) and cytokine-based therapies for the treatment of resistant cases of DM, PM, and IBM. Improved understanding of the molecular mechanisms of muscle injury in the inflammatory myopathies should lead to the development of more specific forms of immunotherapy for these conditions.

Managing Paraneoplastic Neurological Disorders

“…Muscle imaging (CT or MRI) may help in confirming the diagnosis and determining the type of inflammatory myopathy and in selecting an appropriate biopsy site. Muscle or skin biopsy is the definitive diagnostic procedure and shows inflammatory infiltrates [101].…”

Successful Treatment with Tacrolimus in a Case of Refractory Dermatomyositis

“…Although most patients with PM or DM respond well to corticosteroids, 20-30% of cases show an unsatisfactory response and other therapeutic options need to be considered (1). Here, we report a patient with severe DM complicated with rhabdomyolysis and paralytic ileus.…”

Relationship between disease activity and type 1 interferon- and other cytokine-inducible gene expression in blood in dermatomyositis and polymyositis

“…1,2 Clinical and pathological features distinguish subtypes including dermatomyositis (DM), polymyositis (PM), inclusion body myositis (IBM), non-specific myositis and necrotizing myopathy. 3 The incidence of DM/PM has been estimated at 5.5 cases per million people.…”