Inclusion body myositis (IBM) is an inflammatory muscle disease characterized by slowly progressive wasting and weakness of upper extremities. Although there is profound inflammation (invasion of muscle tissue with white blood cells and related substances like antibodies and complements) in the muscle tissue just as observed in other inflammatory autoimmune disorders of the muscle (e.g. polymyositis), the cause does not seem to be autoimmunity. Additionally, in contrast with polymyositis the disease affects men more than women. Symptoms usually begin after 50 years of age. There is no effective treatment for the disease and corticosteroids are used with limited success.