Sarcoid Myopathy and Other Immune-Mediated Granulomatous Myopathies

Abstract

AbstractGranulomatous myositis is a rare disorder characterized by noncaseating granulomatous inflammation of the skeletal muscles, which can configure either an idiopathic entity or accompany several conditions such as sarcoidosis and other inflammatory and infectious diseases. Granulomatous inflammation is infrequently found in skeletal muscle biopsy material. In a large muscle biopsy series, of 2985 specimens reviewed over 12 years, 12 (0.4%) were identified as having granulomatous inflammation, regardless of the clinical manifestations [1]. The incidence and prevalence of granulomatous myositis are unknown since data about this entity is based on case reports or short series of patients. In the setting of sarcoidosis, muscular involvement is reported to occur in 20–80% of patients, but almost always in an asymptomatic fashion [2]. Although the clinical profile together with electromyography (EMG) studies may be useful, a definite diagnosis requires pathological examination. Giant cell myositis shows the presence of giant cells in the absence of granuloma formation and is a close differential diagnosis of granulomatous myositis. Granulomatous myositis and giant cell myositis will be the focus of the discussion.