Novel antibody associations in immune-mediated necrotising myopathy without inflammation
The patient presenting with proximal muscle weakness, elevated serum creatinine kinase and myopathic electromyography and biopsy findings has a wide differential diagnosis that includes toxic, autoimmune, paraneoplastic and congenital myopathies. Autoimmune myopathies are important to identify because they may respond to immunosuppressive therapies.
We describe two cases of immune-mediated necrotizing myopathy each associated with a novel antibody.
Case 1 describes a progressive myopathy in a statin user. Antibodies to 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase were identified and the patient responded to steroid therapy. Case 2 describes an aggressive myopathy associated with antibodies to signal recognition particle. There was no response to steroids. Clinical improvement followed treatment with rituximab and cyclophosphamide.
The identification of myositis-specific antibodies is important because they are associated with distinct clinical phenotypes and may guide the physician in terms of treatment strategies.
KeywordsImmune mediated Necrotizing myopathy 3-Hydroxy-3-methyl-glutaryl-CoA reductase inhibitor Signal recognition particle Antibody
Conflict of interest