Juvenile dermatomyositis

Cutaneous manifestations are usually the form in which juvenile dermatomyositis (JDM) presents and are usually present already in the first weeks of the disease. Muscle involvement is often present from the beginning, and sometimes it is not associated with any symptomatology, so the frequency of muscle involvement at diagnosis will vary depending on whether or not we perform a complete muscle study. Advances in muscle assessment techniques, which we will explain in more detail in another chapter, have reduced the percentage of patients diagnosed as amyopathic (without inflammatory muscle disease associated with skin lesions).