Clinical case of the month. 3-year-old boy presenting with a hand rash. Juvenile dermatomyositis.

Of the diseases within the spectrum of the juvenile idiopathic inflammatory myopathies, juvenile dermatomyositis (JDM) is the most common. As the name implies, JDM affects the muscles and skin most commonly, but can involve other organ systems as well. Dermatologic manifestations often precede other signs and symptoms by months or even years and frequently are the primary reason the patient seeks medical attention. In the case presented here, a 3-year-old boy initially developed a hand rash that brought him to his primary care physician. By the time muscle weakness had developed, the patient had already been evaluated for dermatomyositis and therapy had been initiated. An understanding of these early clinical findings will enable physicians to make a timely diagnosis and commence therapy promptly in order to prevent life-threatening sequelae of the disease.