Clinical myopathy syndromes "Polymyositis" literally means inflammation of multiple muscles and may be due to infections or drug reactions. In the United States, polymyositis more commonly refers to an autoimmune disorder affecting muscle, usually in adulthood. The proximal weakness evolves over weeks to months, affecting patients to different degrees. There may be difficulty climbing stairs, arising from a chair, holding up the head, or raising the arms. A rash involving the periorbital areas and knuckles is typical of dermatomyositis, where both skin and muscle are involved. Some myositis patients have or subsequently develop disorder, and rarely there is an underlying cancer, especially rheumatological a systemic small cell lung carcinoma. EMG testing helps support the clinical diagnosis. Typical muscle biopsy findings show inflammatory cell infiltrates amidst necrotic and regenerating muscle fibers. Most patients improve with oral corticosteroids or other immunosuppressant medication. Muscular dystrophies are hereditary myopathies of variable progression and severity. In some types, patients may be mildly affected or asymptomatic by adulthood while children or teenagers may die from the more severe muscular dystrophies. An example of the latter is Duchenne's (X-linked) muscular dystrophy which involves virtually total deficiency of muscle dystrophin, an important structural protein. Affected young boys begin having more trouble running, climbing or walking. The examiner may observe the Gower's maneuver as the child attempts to get up off the floor using his upper limbs to compensate for weak trunk and pelvic muscles (Fig. 1). The calf muscles (pseudohypertrophy) as muscle is replaced by fat and appear to be unusually enlarged connective tissue. Death occurs after weakening of the respiratory muscles or from the associated cardiomyopathv Other tvnes of muscular dvstronhv are less severe and may primarily affect a few muscles, such as facioscapulohumeral or oculopharyngeal dystrophy. Abnormalities of different muscle membrane proteins or glycoproteir haracterize certain other muscular dystrophies.