Diagnosis and classification of granulomatous myositis.

The term granulomatous myositis is applied to a myopathic syndrome associated with non-specific epithelioid granulomas in striated muscle. This rare entity is most frequently related to sarcoidosis, but other uncommon causes have been reported, including an idiopathic form only after systemic disorders known to cause similar myopathological abnormalities have been excluded. Symmetrical proximal or distal muscle weakness is the rule in the clinical presentation, sometimes associated with dysphagia. Although the clinical profile together with electromyography (EMG) studies may be useful, definite diagnosis requires pathological examination. Systemic glucocorticoids are the treatment of choice, but the clinical outcome is not always satisfactory.