see also:

• dermatomyositis
• inclusion body myositis (IBM)
• connective tissue (CT) disorders

• a chronic inflammatory myopathy related to dermatomyositis and inclusion body myositis (IBM)
• like dermatomyositis, there is a link to underlying cancers but the link is less so, and mainly linked to non-Hodgkin lymphoma, lung cancer and bladder cancer cancers
• ~100-200 cases per million

• often present with painful and marked weakness and/or loss of muscle mass in the proximal musculature, particularly in the shoulder and pelvic girdle (see weakness of the lower limb(s) / weak in the knees)
• hip extensors are often severely affected, leading to particular difficulty in ascending stairs and rising from a seated position
• weakness is generally progressive, accompanied by lymphocytic inflammation (mainly cytotoxic T lymphocytes)
• sclerodactyly, dysphagia or interstitial lung disease may occur

• elevated creatinine kinase (CK), erythrocyte sedimentation rate (ESR)
• Anti Jo antibodies in >65% of patients.
• muscle biopsy

• corticosteroids and other immunosuppressants
• immunoglobulin
• Acthar Gel