4. Rare
Annual incidence :0.4–1.0 cases per
100,000
Female preponderance
Increased with advancing age and reached a
peak at age 50–59 years
sIBM :the most frequent acquired myopathy
after 50 years of age
33. 1. Symmetrical weakness of limb girdle
muscles
2. Elevated levels of muscle enzymes
3. Myopathy on EMG
4. Muscle biopsy evidence of inflammation
5. Skin rash in the case of DM