**1. Introduction**

128 Neuromuscular Disorders

[22] Fasth AE, Dastmaich M, Rahbar A, Saiomonsson S, Pandya JM, Lindroos E, Nennesmo

are dominated by CD28null T cells. J Immunol 2009; 183: 4792-4799. [23] Dalakas MC. Immunotherapy of inflammatory myopathies: practical approach and

future prospects. Curr Treat Options Neurol 2011; 13: 311-323.

I, Malmberg KJ, Soderberg-Naucler C, Trollmo C, Lundberg IE, Malmstrom V. T cell infiltrates in the muscles of patients with dermatomyositis and polymyositis

> **1.1** Dermatomyositis is an autoimmune inflammatory myopathy with diffuse nonsuppurative inflammation of the skin and striated muscles. {In polymyositis, skeletal muscles only are involved.]

> **1.2** The disease is uncommon, occurs twice as often in female patients, and most present between 40 and 60 years of age, with a smaller peak between the ages of 5 and 15. There is a two-to-seven fold increase in the frequency of malignancy, especially in older patients in the adult age group (about 21% for dermatomyositis and 15% for polymyositis) (Hansell, et al., 2005).
