INCLUSION-BODY MYOSITIS

Inclusion body myositis is a distinct entity among the idiopathic inflammatory myopathies which encompass polymyositis, dermatomyositis, and inclusion body myositis. The diagnosis of inclusion body myositis requires the consistent combination of characteristic clinical findings with distinctive histopathological features. The main clinical features are insidious onset of slowly progressive muscular weakness and wasting, normal or mildly elevated CK-levels, EMG findings consistent with a myopathy, and refractoriness to corticosteroids. The histological hallmarks of the disease include vacuoles rimmed by basophilic material in numerous muscle fibres, groups of atrophic fibres, endomysial inflammatory infiltrates, and filamentous inclusions seen on electron microscopy. Current knowledge of clinical findings, histological features, pathogenesis and treatment of the disease is reviewed.