Granulomatous myositis: A clinical study of thirteen cases

Abstract

Granulomatous myositis (GM) is a rare condition that has generally been described in association with sarcoidosis. In the absence of sarcoidosis or other underlying disease, a diagnosis of isolated GM is considered. Only one study has focused on the clinical difference between isolated GM and sarcoid myopathy (SM). We report 13 cases of symptomatic GM; 8 had sarcoidosis. All patients with sarcoidosis had predominantly proximal, symmetrical lower-limb weakness, and 3 subsequently developed upper-limb or distal involvement. Three of the five patients with isolated GM had predominantly distal muscle involvement, and two had dysphagia. Corticosteroid treatment was followed by prolonged improvement in only one patient with sarcoidosis. One patient had acute sarcoid myositis and benefited from methotrexate; other immunosuppressants and etanercept proved ineffective in chronic sarcoid myopathy. Three of the five patients with isolated GM responded to corticosteroid treatment. When last examined, three patients with sarcoidosis had severe disability, whereas patients with isolated GM showed milder weakness. Thus, SM was frequently associated with severe disability and rarely improved after corticosteroid treatment, whereas most patients with isolated GM improved.

Inclusion body myositis with granuloma formation in muscle tissue

“…There are several reports of patients with GM showing the following features: myositis with granuloma, no evidence of sarcoidosis, and a good response to immunotherapy [2,9]. Somewhat interestingly, some GM patients mimicked IBM in clinical characteristics; however, these cases showed no pathological features consistent with IBM, such as rimmed vacuole, amyloid deposition or abnormal protein accumulation in muscle fiber [12].…”

“…The presence of Langerhans-type or histiocytic giant cells was unnecessary to be judged as granulomas [9]. We paid special attention to exclude necrotic regions to avoid including caseating granulomas [9].…”

Coexisting primary Sjögren’s syndrome and sarcoidosis: coincidence, mutually exclusive conditions or syndrome?

“…the finding of granulomatous myositis is highly suggestive of sarcoid myopathy. however, this is not a common finding: In a literature review of 26 patients with pSS and coexisting sarcoidosis, only one patient had sarcoid involvement of the muscles [14,15].…”

Observations on the classification of the inflammatory myopathies

“…A clinical pattern similar to sIBM, with distal weakness affecting the finger flexors, has been described [40]. Response to immunosuppressant therapy is often poor.…”