Abstract
The idiopathic inflammatory myopathies are a group of rare disorders that share many
similarities. These include dermatomyositis (DM), polymyositis (PM), necrotizing myopathy
(NM), and sporadic inclusion body myositis (IBM). Inclusion body myositis is the most
common idiopathic inflammatory myopathy after age 50 and it presents with chronic
proximal leg and distal arm asymmetric mucle weakness. Despite similarities with PM,
it is likely that IBM is primarily a degenerative disorder rather than an inflammatory
muscle disease. Inclusion body myositis is associated with a modest degree of creatine
kinase (CK) elevation and an abnormal electromyogram demonstrating an irritative myopathy
with some chronicity. The muscle histopathology demonstrates inflammatory exudates
surrounding and invading nonnecrotic muscle fibers often times accompanied by rimmed
vacuoles. In this chapter, we review sporadic IBM. We also examine past, essentially
negative, clinical trials in IBM and review ongoing clinical trials. For further details
on DM, PM, and NM, the reader is referred to the idiopathic inflammatory myopathies
chapter.
Keywords
inclusion body myositis - idiopathic inflammatory myopathies - polymyositis - pathophysiology
- therapy - prognosis
