An inflammatory disease marked by muscle weakness and skin rash.

Dermatomyositis (dur-muh-toe-my-uh-SY-tis) usually occurs from the late 40s to early 60s in adults and from ages 5 to 15 in children. Females are most affected.

Symptoms include a rash on the face and eyelids, and in areas around the nails, knuckles, elbows, knees, chest and back. Muscle weakness can affect the hips, thighs, shoulders, upper arms and neck. The weakness affects both the left and right sides of the body and gradually gets worse.

Treatment can improve the skin and muscle strength and function. Treatment may include medicine, physical therapy or other therapies. Surgery may be used to remove calcium deposits.