Inflammatory myopathy that progresses slowly over years.

Symptoms:- Selective and asymmetric muscle involvement of both proximal and distal muscle groups- Quadriceps muscle weakness: knees lack support → frequent falling- Finger flexors: difficulties gripping, eg, shopping bags or a briefcase

Pathology:- Vacuoles within the muscle fiber

Diagnosis:- ↑ Muscle enzymes, eg CK- Electromyography- Muscle biopsy: Inflammation and vacuoles

Treatment: Exercise, physical therapy