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Department of Medicine

Department of Medicine

  Division of Rheumatology and Clinical Immunology

CENTERS AND INSTITUTES


Myositis


Myositis

DEFINITION

The idiopathic inflammatory myopathies (IIM) are a group of heterogeneous autoimmune syndromes characterized primarily by muscle weakness but also associated with many other systemic symptoms. The conventional classification of IIM (or myositis) includes the following subsets:

Each of the subsets is characterized by certain unique features. As one would expect, patients with DM have characteristic skin rashes even though they may have the same pattern of muscle weakness found in patients with PM. Individuals with cancer-associated myositis often have DM more frequently than PM and a number of different malignancies can be seen with myositis. Patients with myositis and another CTD may have features of scleroderma, lupus or even combined findings of several different rheumatic diseases. IBM patients have a unique pattern of muscle weakness that is distinct from that seen in PM or DM.