Skeletal muscle disease.

Part of the idiopathic inflammatory group of skeletal muscle disorder.

Can manifest as a focal lesion in muscle in association with fever and antecedent trauma or inan iimmunocompromised or malnourished host.

Symmetric proximal muscle weakness that develops over weeks to months.

Maybe associated with difficulty swallowing, and sometimes dyspnea when respiratory muscles are involved.

Associated with malignancies.

Shares many clinical features with dermatomyositis.

Has a distinct immuno histopathological phenotype involving CD8 positive cytotoxic T cells that invade non necrotic muscle fibers.

Most common inflammatory myopathy in individuals over the age of 50 years.

Immune mediated inflammation present in muscles.

Incidence 1 in 100,000 people annually.

More common among African Americans with a ratio of 5:1 over whites.

2:1 female: male ratio.

Rare before the age of 20 years.

Usually painless, but myalgias may be present in 30% of patients.

If esophageal or pharyngeal muscles are involved there may be dysphasia or aspiration present.

Patients may experience arthralgias.

Patients may have difficulty raising their arms, kneeling, holding head erect, and usually have more lower than upper body weakness.

Palpation indicates the presence of tender muscles.

Patients usually have a normal sensory and reflex examination.

Extra muscular manifestation include congestive heart failure, interstitial lung disease, dysphasia and arthralgias with symmetric arthritis.

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